Water is key to ending Africa’s chronic hunger cycle

By Esther Ngumbi

For Africa to end chronic hunger, governments must invest in sustainable water supplies.

The fields are bare under the scorching sun and temperatures rise with every passing week. Any crops the extreme temperatures haven’t destroyed, the insect pests have, and for many farmers, there is nothing they can do. Now, news about hunger across Africa makes mass media headlines daily.

Globally, hunger levels are at their highest. In fact, according to the Famine Early Warning Systems Network, over 70 million people across 45 countries will require food emergency assistance in 2017, with Africa being home to three of the four countries deemed to face a critical risk of famine: Nigeria, South Sudan, Sudan and Yemen. African governments, non-governmental organisations (NGOs) and humanitarian relief agencies, including the United Nations World Food Programme, continue to launch short-term solutions such as food relief supplies to avert the situation. Kenya, for example, is handing cash transfers and food relief to its affected citizens. The UN World Food Programme is also distributing food to drought-stricken Somalia. And in Zambia, the government is employing every tool including its military to combat insect pest infestation.

But why are we here? What happened? Why is there such a large drought?

Reasons for chronic hunger

Many African smallholder farmers depend on rain-fed agriculture, and because last year’s rains were inadequate, many farmers never harvested any crops.

Indeed, failed rains across parts of the Horn of Africa have led to the current drought that is affecting Somalia, south-eastern Ethiopia and northern and eastern Kenya.

Then, even in the countries where adequate rains fell, many of the farmers had to farm on depleted soils, and consequently, the yields were lower. Degraded soils and dependence on rain-fed agriculture coupled with planting the wrong crop varieties are some of the fundamental problems that lead to poor harvests and then to hunger. Worsening the situation is the unpredictable climate. Given these fundamental and basic issues that fuel the hunger cycle in Africa, it naturally makes sense to tackle them.

It is not rocket science. Farming goes hand-in-hand with water. There can be no farming without it. While this seems easy to reason, there are few organisations working to make sure that African farmers and citizens have access to permanent water sources. Access to water sources all year round would ensure that farmers can farm year in and year out.

What African governments must do

African governments must, therefore, invest in ensuring that their citizens have access to water. Measures that can be implemented include drilling and rehabilitating boreholes, creating reservoirs and irrigation systems, constructing hand-pumps and implementing water harvesting schemes. Such measures would go a long way and ensure that countries continue to face the same problem both in the short and long term periods.

“If Africa wants to end the recurring droughts, hard decisions must be made.”

Esther Ngumbi, Auburn University in Alabama. United States

Of course it is understandable that it can be hard to choose long-term solutions such as ensuring that citizens have access to permanent water sources year round over investing in short-term solutions when there are people who need help now.

Acknowledging this dilemma, Mitiku Kassa, the Ethiopia’s commissioner for disaster risk management, is reported to have described how hard it was to direct even a fifth of his budget towards well drilling. But such decisions must be made. The Ethiopian government still made that tough decision and sunk hundreds of bore wells throughout the country.

There is a great need to ramp up water harvesting and conservation efforts across the African continent. African governments and other stakeholders need to increase investment in multiple water-storing techniques. Such techniques include rain and flood water harvesting and the construction of water storage ponds and dams. But there should be no need to reinvent the wheel.

Time to learn from others

African countries can learn from other countries. Countries in the developed world have sustained their agriculture efforts by either drilling water wells to ensure they have access to the water they need for farming or by investing in rain and flood water harvesting. In California, for example, there have been a rise in the number of wells being drilled by farmers who use well water for farming. In 2016 alone, farmers in the San Joaquin Valley dug about 2,500 wells, a number that was five times the annual average reported in the last 30 years.

Countries such as Bangladesh, China, India, Myanmar, Sri Lanka and Thailand have made progress and are working on pilot projects that capture, harvest and store flood water. Stored water is then available for use by communities when they need it the most. Harvesting and storing water and making it available for agriculture, especially during the dry seasons, will allow citizens and smallholder farmers to farm throughout the year. These would further improve the resilience of farmers to the unpredictability of climate change.

If Africa wants to end the recurring droughts, hard decisions must be made. By addressing the fundamental and basic issues of long-term availability of water for agriculture, African countries can once and for all end this never-ending cycle of hunger.

Esther Ngumbi is a postdoctoral researcher at the Department of Entomology and Plant Pathology at Auburn University in Alabama, United States. She serves as a 2015 Clinton Global University (CGI U) Mentor for Agriculture and is a 2015 New Voices Fellow at the Aspen Institute. 

This piece was produced by SciDev.Net’s Sub-Saharan Africa English desk.

 

References

Humphrey Nkonde Dramatic threat to maize harvest (Development and Cooperation, 6 March 2017)
Mohammed Yusuf UN: 17 Million People Face Hunger East Africa (Voice of America, 8 March 2017)
Karen McVeigh Somalia famine fears prompt UN call for ‘immediate and massive’ reaction (the Guardian, 3 February 2017)
Emergency food assistance needs unprecedented as Famine threatens four countries (Famine Early Warning Systems Network, 25 January 2017)
Kazungu Samuel Kenya: Red Cross Comes to the Aid of Drought-Hit Kilifi Residents (allAfrica, 2017)
Army worms invades Zambia’s farms (Azania Post, 6 February 2017)
Lesson learned? An urgent call for action in response to the drought crisis in the horn of Africa (Inter Agency Working Group on Disaster Preparedness for East and Central Africa, 2017)
Amanda Little The Ethiopian Guide to Famine Prevention (Bloomberg Business Week, 22 December 2016)
Central Valley farmers drill more, deeper wells as drought limits loom (CBS SF Bay Area, 15 September 2016)
Underground taming floods for irrigation(International Water Management Institute, 2017)

 

This article was originally published on SciDev.Net. Read the original article.

How diverse is your food?

Dr Colin Khoury

Dr Colin Khoury

This post was written by Dr Colin Khoury. Colin studies diversity in the crops people grow and eat worldwide, and the implications of change in this diversity on human health and environmental sustainability. He is particularly interested in the wild relatives of crops. Colin is a research scientist at the International Center for Tropical Agriculture (CIAT), Colombia, and at the USDA National Laboratory for Genetic Resources Preservation in Fort Collins, Colorado.

 

New Changing Global Diet website explores changes in diets over the past 50 years in countries around the world.

One of the central concepts that unifies those concerned with biodiversity is the understanding that this diversity is being lost, piece by piece, to a greater or lesser degree, globally.

The same goes for the biodiversity of what we eat. Scientists and activists have worried about the loss of crops and their many traditional varieties for at least a hundred years, since botanist N. I. Vavilov traveled the world in search of plants useful for cultivation in his Russian homeland. He noticed that diversity was disappearing in the cradles of agriculture – places where crops had been cultivated continuously for thousands of years. The alarm sounded even louder 50 years ago, during the Green Revolution, when farmers in some of the most diverse regions of the world largely replaced their many locally adapted wheat, rice and other grain varieties with fewer, more uniform, higher yielding professionally bred varieties.

 

Map of crop diversity

Cradles of agriculture: origins and primary regions of diversity of agricultural crops

(Click to magnify)

 

This is ironic, since modern productive crop varieties are bred by wisely mixing and matching diverse genetic resources. The disappearance of old varieties thus reduces the options available to plant breeders, including those working to produce more nutritious or resilient crops.

Being a food biodiversity scientist, I grew up (in the professional sense) with the loss of crop diversity looming over my head, providing both a raison d’être, and an urgency to my efforts. Somewhere along the line, I became interested in understanding its magnitude. That is, counting how many crops and how many varieties have been lost.

That’s where it started to become complicated, and also more interesting. Because, when I went looking for signs of the loss of specific crops, I couldn’t find any. Instead, I found evidence of massive global changes in our food diversity that left me worried, but at the same time hopeful.

A bit of background. Most of the numbers seen in the news on how much crop diversity has been lost go back to a handful of reports and books that reference a few studies: for example, the changing number of vegetable varieties for sale in the U.S. over time. The results are estimations for a few crops at local to national levels, but they somehow have been inflated to generalized statements about the global state of crop diversity, the most common of which being some variation of “75% of diversity in crops has been lost”.

Market stand of fruit and vegetables

Diverse produce, but is it all local? Image credit:  Karyn Christner. Used under license: CC BY 2.0.

Putting true numbers on diversity loss turns out to be a complicated and contested business, with no shortage of strong opinions. One big part of the problem is that there aren’t many good ways to count the diversity that existed before it disappeared. Researchers have done some work to assess the changes in diversity in crop varieties of Green Revolution cereals, and to some degree on the genetic diversity within those varieties. The results indicate that, although diversity on farms decreased when farmers first replaced traditional varieties with modern types, the more recent trends are not so simple to decipher.

It was particularly surprising to me that very little work had been done to understand the changes in what is probably the simplest level to measure: the diversity of crop species in the human diet, that is, how successful is maize versus rice versus potato versus quinoa and so on. I realized that data on the contribution of crops to national food supplies were available for almost all countries worldwide via FAOSTAT, with information for every year since 1961. Perhaps these were the data that could show when a crop fell off the world map.

Fast forward through a couple of years of investigation. To my great surprise, I found that not a single crop was lost over the past 50 years! There was no evidence for extinction. What was going on?

Maize

Maize is a key crop in many countries. Image credit: Erfan A. Setiawan. Used under license: CC BY 2.0.

It turns out that my failure to see any loss of crops was due to the lack of sufficient resolution in the FAO data. Only 52 meaningful crop species-specific commodities are measured and a number of these are general groupings such as “cereals, other”. Because of this lack of specificity, the data couldn’t comprehensively assess the crops that have been most vulnerable to changes in the global food system over the past 50 years. In FAO data, these plants are either thrown into the general categories or they aren’t measured at all, especially if they are produced only on a small scale, for local markets or in home gardens. This is, in itself, sign enough that they may be imperiled. We need better statistics about what people eat (and grow) around the world. But, enough is known to be confident that many locally relevant crops are in decline.

Over the past 50 years, almost all countries’ diets actually became more diverse, not less, for the crops that FAO statistics do report on. We found that traditional diets that were primarily based on singular staples a half century ago, for instance rice in Southeast Asia, had diversified over time to include other staples such as wheat and potatoes. The same was true for maize-based diets in Latin America, sorghum- and millet-based diets in sub-Saharan Africa, and so on.

Not that there weren’t plant winners and losers. Wheat, rice, and maize, the most dominant crops worldwide 50 years ago, became more important globally. Other crops emerged as widespread staples, particularly oilcrops such as soybean, palm oil, sunflower, and rapeseed oil. And, as the winners came to take more precedence in food supplies around the world, alternative staples such as sorghum, millets, rye, cassava, sweet potato, and yam were marginalized. They haven’t disappeared (at least not yet), but they have become less important to what is eaten every day.

As countries’ food supplies became more diverse in the winner crops reported by FAO, and the relative abundance of these crops within diets became more even, food supplies worldwide became much more similar, with an average decrease in variation between diets in different countries of 68.8% over the past 50 years!

This is why, although we could see no absolute loss in crops consumed over the past 50 years, I am concerned. For even in the relatively small list of crops reported in the FAO data, many of these foods are becoming marginalized, day by day, bite by bite. That doesn’t seem like a good thing for the long-term resilience of our agricultural areas, nor for human health, although it’s important to remember that such changes are the collateral damage resulting from the creation of highly productive mega-crop farming systems, which have increased the affordability of these foods worldwide, leading to less stunting and other effects of undernutrition worldwide. On the other hand, global dependence on a few select crops equates to expansive monocultures, with more lives riding on the outcome of the game of cat and mouse between pestilence and uniform varieties grown over large areas. Moreover, cheaply available macronutrients have contributed to the negative effects of the nutrition transition, including obesity, heart disease and diabetes.

So why then am I hopeful? Because the data, and some literature, and my own direct experience also indicate that diets in recent years, in some countries, are beginning to move in different directions, reducing the excessive use of animal products and other energy-dense and environmentally expensive foods, and becoming more diverse, particularly with regard to fruits and vegetables, and even healthy grains. What better evidence than quinoa, which was relatively unknown outside the Andes a couple of decades ago, and is now cultivated in 100 countries and consumed in even more?

When we published our findings of increasing homogeneity in global food supplies, we hadn’t yet found a good way to make the underlying national-level data readily visible to interested readers. This is why I’m tremendously excited to announce the publication of our new Changing Global Diet website, which provides interactive visuals for 152 countries over 50 years of change. We that hope you will enjoy your own investigations of dietary change over time. Perhaps you can tell us where you think the changing global diet is headed.

Check out The Changing Global Diet website


Read the published article: Khoury CK, Bjorkman AD, Dempewolf H, Ramírez-Villegas J, Guarino L, Jarvis A, Rieseberg LH and Struik PC (2014). Increasing homogeneity in global food supplies and the implications for food security. PNAS 111(11): 4001-4006.

Healthy soil is the real key to feeding the world

By David R. Montgomery, University of Washington

 

Image 20170329 8557 1q1xe1z
Planting a diverse blend of crops and cover crops, and not tilling, helps promote soil health. Catherine Ulitsky, USDA/Flickr, CC BY

 

One of the biggest modern myths about agriculture is that organic farming is inherently sustainable. It can be, but it isn’t necessarily. After all, soil erosion from chemical-free tilled fields undermined the Roman Empire and other ancient societies around the world. Other agricultural myths hinder recognizing the potential to restore degraded soils to feed the world using fewer agrochemicals. The Conversation

When I embarked on a six-month trip to visit farms around the world to research my forthcoming book, “Growing a Revolution: Bringing Our Soil Back to Life,” the innovative farmers I met showed me that regenerative farming practices can restore the world’s agricultural soils. In both the developed and developing worlds, these farmers rapidly rebuilt the fertility of their degraded soil, which then allowed them to maintain high yields using far less fertilizer and fewer pesticides.

Their experiences, and the results that I saw on their farms in North and South Dakota, Ohio, Pennsylvania, Ghana and Costa Rica, offer compelling evidence that the key to sustaining highly productive agriculture lies in rebuilding healthy, fertile soil. This journey also led me to question three pillars of conventional wisdom about today’s industrialized agrochemical agriculture: that it feeds the world, is a more efficient way to produce food and will be necessary to feed the future.

Myth 1: Large-scale agriculture feeds the world today

According to a recent U.N. Food and Agriculture Organization (FAO) report, family farms produce over three-quarters of the world’s food. The FAO also estimates that almost three-quarters of all farms worldwide are smaller than one hectare – about 2.5 acres, or the size of a typical city block.

 

A Ugandan farmer transports bananas to market. Most food consumed in the developing world is grown on small family farms.Svetlana Edmeades/IFPRI/Flickr, CC BY-NC-ND

 

Only about 1 percent of Americans are farmers today. Yet most of the world’s farmers work the land to feed themselves and their families. So while conventional industrialized agriculture feeds the developed world, most of the world’s farmers work small family farms. A 2016 Environmental Working Group report found that almost 90 percent of U.S. agricultural exports went to developed countries with few hungry people.

Of course the world needs commercial agriculture, unless we all want to live on and work our own farms. But are large industrial farms really the best, let alone the only, way forward? This question leads us to a second myth.

Myth 2: Large farms are more efficient

Many high-volume industrial processes exhibit efficiencies at large scale that decrease inputs per unit of production. The more widgets you make, the more efficiently you can make each one. But agriculture is different. A 1989 National Research Council study concluded that “well-managed alternative farming systems nearly always use less synthetic chemical pesticides, fertilizers, and antibiotics per unit of production than conventional farms.”

And while mechanization can provide cost and labor efficiencies on large farms, bigger farms do not necessarily produce more food. According to a 1992 agricultural census report, small, diversified farms produce more than twice as much food per acre than large farms do.

Even the World Bank endorses small farms as the way to increase agricultural output in developing nations where food security remains a pressing issue. While large farms excel at producing a lot of a particular crop – like corn or wheat – small diversified farms produce more food and more kinds of food per hectare overall.

Myth 3: Conventional farming is necessary to feed the world

We’ve all heard proponents of conventional agriculture claim that organic farming is a recipe for global starvation because it produces lower yields. The most extensive yield comparison to date, a 2015 meta-analysis of 115 studies, found that organic production averaged almost 20 percent less than conventionally grown crops, a finding similar to those of prior studies.

But the study went a step further, comparing crop yields on conventional farms to those on organic farms where cover crops were planted and crops were rotated to build soil health. These techniques shrank the yield gap to below 10 percent.

The authors concluded that the actual gap may be much smaller, as they found “evidence of bias in the meta-dataset toward studies reporting higher conventional yields.” In other words, the basis for claims that organic agriculture can’t feed the world depend as much on specific farming methods as on the type of farm.

 

Cover crops planted on wheat fields in The Dalles, Oregon.
Garrett Duyck, NRCS/Flickr, CC BY-ND

 

Consider too that about a quarter of all food produced worldwide is never eaten. Each year the United States alone throws out 133 billion pounds of food, more than enough to feed the nearly 50 million Americans who regularly face hunger. So even taken at face value, the oft-cited yield gap between conventional and organic farming is smaller than the amount of food we routinely throw away.

Building healthy soil

Conventional farming practices that degrade soil health undermine humanity’s ability to continue feeding everyone over the long run. Regenerative practices like those used on the farms and ranches I visited show that we can readily improve soil fertility on both large farms in the U.S. and on small subsistence farms in the tropics.

I no longer see debates about the future of agriculture as simply conventional versus organic. In my view, we’ve oversimplified the complexity of the land and underutilized the ingenuity of farmers. I now see adopting farming practices that build soil health as the key to a stable and resilient agriculture. And the farmers I visited had cracked this code, adapting no-till methods, cover cropping and complex rotations to their particular soil, environmental and socioeconomic conditions.

Whether they were organic or still used some fertilizers and pesticides, the farms I visited that adopted this transformational suite of practices all reported harvests that consistently matched or exceeded those from neighboring conventional farms after a short transition period. Another message was as simple as it was clear: Farmers who restored their soil used fewer inputs to produce higher yields, which translated into higher profits.

No matter how one looks at it, we can be certain that agriculture will soon face another revolution. For agriculture today runs on abundant, cheap oil for fuel and to make fertilizer – and our supply of cheap oil will not last forever. There are already enough people on the planet that we have less than a year’s supply of food for the global population on hand at any one time. This simple fact has critical implications for society.

So how do we speed the adoption of a more resilient agriculture? Creating demonstration farms would help, as would carrying out system-scale research to evaluate what works best to adapt specific practices to general principles in different settings.

We also need to reframe our agricultural policies and subsidies. It makes no sense to continue incentivizing conventional practices that degrade soil fertility. We must begin supporting and rewarding farmers who adopt regenerative practices.

Once we see through myths of modern agriculture, practices that build soil health become the lens through which to assess strategies for feeding us all over the long haul. Why am I so confident that regenerative farming practices can prove both productive and economical? The farmers I met showed me they already are.

David R. Montgomery, Professor of Earth and Space Sciences, University of Washington

This article was originally published on The Conversation. Read the original article.

Drought-resistant grass to spur milk production

By Baraka Rateng’

Struggling East African dairy farmers could benefit from new varieties of high-quality, drought-resistant forage grass known as Brachiaria that boosts milk production by 40 per cent, a report says.

The forage grass could enable farmers to increase their incomes, according to experts at the Colombia-headquartered International Center for Tropical Agriculture (CIAT) – a CGIAR Research Center.

Steven Prager, a co-author of the report —  which was published last month — and a senior scientist in integrated modelling at the CIAT, says the report  was based on many years of forage research in Latin America and the Caribbean, and recent field trials in Kenya and Rwanda from 2011 to 2016.

According to Prager, the study demonstrates the high potential for improved forages in East Africa and high payoff for investment in improved forages.

“The results are based on multiple scenarios of an economic surplus model with inputs derived from a combination of databases, feedback from subject matter experts and a literature review,” he explains, adding that the economic analysis was carried out at CIAT headquarters with the support of tropical forage experts in East Africa.

Drought resistant grass
“The objective of this study was to understand the potential payoff for investment in action to improve dissemination and use of improved forages,” Prager tells SciDev.Net.

“The objective of this study was to understand the potential payoff for investment in action to improve dissemination and use of improved forages.”

Steven Prager, International Center for Tropical Agriculture (CIAT)

One of the big unknowns in the development and implementation of agricultural technology, according to Prager, is how many potential users are required to make it worthwhile to invest in the development and designation of different technologies.

Solomon Mwendia, a co-author of the report and forage agronomist at CIAT, Kenya, says the Brachiaria grass is climate-friendly and has high crude protein and less fiber, which leads to better use and digestion by cattle, in turn leading to less methane gas produced for each unit of livestock product such as milk or meat. Methane is one of the gases associated with global warming.

“This grass is relatively drought-tolerant compared to the Napier or elephant grass commonly used in East Africa. In addition, the grass can easily be conserved as hay for utilisation during forages scarcity or for sale,” Mwendia adds.

Smallholder dairy farming is important in East Africa for household nutrition and income. In Kenya, for instance, Mwendia says that milk production increased by 150 per cent between 2004 and 2012, from 197.3 million litres to 497.9 million litres.


East Africa cattle density 


The grass is native to Africa, according to Mwendia. It can grow in areas with up to 3,000 millimetres of rainfall and also withstand dry seasons of three to six months during which the leaf may remain green while other tropical species die. These conditions exist in other regions outside eastern Africa such as in Democratic Republic of Congo, Malawi, Zambia and Zimbabwe.

Sita Ghimire, a senior scientist at the Biosciences eastern and central Africa (BecA) Hub, who leads a research programme that focuses on Brachiaria, says 40 per cent increase in milk production is achievable in East Africa after feeding livestock with Brachiaria.


Livestock production in East Africa 


“Forage has been always a major challenge in livestock production in East Africa. It is mainly because of declining pastureland, frequent and prolonged drought and not many farmers conserve forage for dry season,” Ghimire says.

The major challenges for adoption of Brachiaria technology in East Africa are limited availability of seeds or  vegetative materials, lack of standardised agronomic practices for different production environments and lack of varieties that are well adapted to East African environment, Ghimire explains, citing other challenges such as pest and diseases, and low funding forage research and development.

This piece was produced by SciDev.Net’s Sub-Saharan Africa English desk.

References

Carlos González and others Improved forages and milk production in East Africa. A case study in the series: Economic foresight for understanding the role of investments in agriculture for the global food system (October 2016, Internacional de Agricultura Tropical [CIAT])

 

This article was originally published on SciDev.Net. Read the original article.

Plantwise – promoting and supporting plant health for the Sustainable Development Goals

Andrea Powell

Andrea Powell, CABI

Promoting and supporting plant health will be an important part of how we achieve the United Nations’ Sustainable Development Goals (SDGs). Andrea Powell, Chief Information Officer of the Centre for Agriculture and Biosciences International (CABI) looks at how the CABI-led Plantwise programme is helping to make a difference.

By Andrea Powell

 

On 26th and 27th July 2016, CABI held its 19th Review Conference. This important milestone in the CABI calendar saw our 48 member countries come together to agree a new medium-term strategy. As always, plant health was a key focus to our discussions, cutting across many of CABI’s objectives. For CABI, with 100 years of experience working in plant health, it has become one of our most important issues, upon which our flagship food security program, Plantwise, has been built.

Plant health can, quite simply, change the lives and livelihoods of millions of people living in rural communities, like smallholder farmers. Human and animal health make headlines, while plant health often falls under the radar, yet, it is crucial to tackling serious global challenges like food security. Promoting and supporting plant health will be an important way to achieve the Sustainable Development Goals (SDGs).

Plant health and the SDGs

Take, for example, SDG 1, which calls for ‘no poverty’. The UN states that one in five people in developing regions still lives on less than $1.25 a day. We know that many of these people are smallholder farmers. By breaking down the barriers to accessing plant health knowledge, millions of people in rural communities can learn how to grow produce to sell to profitable domestic, regional and international markets.

Plantwise ReportSDG 2 focuses on achieving ‘zero hunger’. Almost one billion people go hungry and are left malnourished every day – and many are children. Subsistence farmers, who grow food for their families to eat, can be left with nothing when their crops fail. Access to plant health knowledge can help prevent devastating crop losses and put food on the table.

Interestingly, SDG 17 considers ‘partnerships for the goals’ and is critical to the way in which we can harness and share plant health knowledge more widely to help address issues like hunger and poverty. By themselves, individual organizations cannot easily resolve the complicated and interconnected challenges the world faces today. This is why partnership is at the heart of CABI’s flagship plant health programme: Plantwise.

What is Plantwise?

Plantwise Report 2015

Since its launch in 2011, the goal of Plantwise has been to deliver plant health knowledge to smallholder farmers, ensuring they lose less of what they grow. This, in turn, provides food for their families and improves living conditions in rural communities. Plantwise provides support to governments, helping to make national plant health systems more effective for the farmers who depend on them. Already, Plantwise has reached nearly five million farmers. With additional funding, and by developing new partnerships, we aim to bring relevant plant health information to 30 million farmers by 2020, safeguarding food security for generations to come.

Plantwise ‘plant clinics’ are an important part of the fight against crop losses. Established in much the same way as clinics for human health, farmers visit the clinics with samples of their sick crops. Plant doctors diagnose the problem, making science-based recommendations on ways to manage it. The clinics are owned and operated by over 200 national partner organizations in over 30 countries. At the end of 2015, nearly five thousand plant doctors had been trained.

Plantwise

A Plantwise plant clinic in action. Credit: Plantwise

Harnessing technology for plant health

The Plantwise Knowledge Bank reinforces the plant clinics. Available in over 80 languages, it is an online and offline gateway to plant health information, providing the plant doctors with actionable information. It also collects data about the farmers, their crops and plant health problems. This enables in-country partner organizations to monitor the quality of plant doctor recommendations; to identify new plant health problems – often emerging due to trade or climate change issues; and develop new best-practice guidelines for managing crop losses.

Plantwise

The first ever e-plant clinic, held in Embu Market, Kenya. Credit: Plantwise

The Plantwise flow of information improves knowledge and helps the users involved: farmers can receive crop management advice, and researchers and governments can access data from the field. With a new strategy for 2017–19 agreed, CABI will continue to focus on building strong plant health systems. We are certain that plant health is of central importance to achieving the SDGs and, together in partnership, we look forward to growing the Plantwise program and making a concrete difference to the lives of smallholder farmers.

“A few years ago, I would make ZMW 5000 per year. Last year I got 15 000. I have never missed any plant clinic session. I’ve been very committed, very faithful, because I have seen the benefits.”––Kenny Mwansa, Farmer, Rufunsa District, Zambia.

Take a look at Plantwise in action in Zambia (YouTube):

Plantwise in Zambia

Meet Linda, a Zambian plant doctor

Meet Kenny, a Zambian farmer

 

Learn more about Plantwise at www.plantwise.org.

Lessons from the oldest and most arid desert on Earth

Atacama Desert

Image credit: Center for Genome Regulation

The Atacama Desert is a strip of land near 1000 km in length located in northern Chile. With an average yearly rainfall of just 15 mm (close to 0 in some locations) and high radiation levels, it is the driest desert in the world. Geological estimates suggest that the Atacama has remained hyperarid for at least eight million years. Standing in its midst, one may easily feel as though visiting a valley on Mars.

Despite these harsh environmental conditions, it is possible to find life in the Atacama. At the increased altitudes along the western slopes of the Andes precipitation is slightly increased, allowing plant life.

Convergent evolution

The driest and oldest desert in the world acts as a natural laboratory where for 150 million years plants adapted to and colonized this environment. These adaptations are likely present in multiple desert plant lineages, thus providing an evolutionary framework where these traits can be associated with a signature of convergent evolution.

Surviving a nitrogen-limited landscape

Plant in the Atacama Desert

Image credit: Center for Genome Regulation

The interplay of environmental conditions in the transect of the Atacama, ranging from 2500 to 4500 meters above sea level, results in three broad microclimates; Pre Puna, Puna, and High Steppe. These microclimates have different humidities, temperatures, levels of organic matter and even different pH levels, but share one common feature: low nitrogen levels.

To engineer crops with higher nitrogen use efficiency, it is very useful to first learn how plants adapt to growth in low nitrogen environments. Here the Atacama Desert enters into the game. Plants growing in the desert can survive 100-fold less nitrogen below optimum concentrations. Using phylogenetics it is possible to uncover novel genes and mechanisms related to adaptation to these extreme conditions, which have not been discovered through traditional genetic approaches.

Currently, nitrogen fertilizers are widely employed to increase crop yield. In 2008 100 million tons of this fertilizer were used and it is projected that for 2018 the demand for nitrogen will rise to 119 million tons. Regretfully, the production and over-usage of this type of fertilizer has an enormous impact in the environment and human health. Around 60% of the nitrogen introduced to the soil for agricultural purposes is leached and lost. Moreover, nitrogen runoffs to the water cause eutrophication in both freshwater and marine ecosystems, leading to algae and phytoplankton blooms, low levels of dissolved oxygen, and finally the migration or death of the present fauna, forming dead zones such as the one in the Gulf of Mexico.
 

Plants in the Atacama Desert

Image credit: Center for Genome Regulation

Nitrogen fertilizers are not the only major concern in modern agricultural procedures. The co-localization of drought and low nitrogen levels is especially detrimental for plant growth and development. We need to support not only the nutritional requirement of an expanding global population but also new energetic strategies based on production of biomass for biofuels on marginal nutrient poor soils. In order to increase crop yields while reducing the environmental impact of nitrogen fertilizers, it is necessary to develop new agricultural strategies and cutting edge technologies.

Learning from the desert

What if we could profit from the extraordinary plants that have had thousands of years to learn how to cope with nitrogen scarcity, drought and extreme radiation? Specifically, can we unravel the genes and mechanisms that allow them to survive in such a barren place?

Atacama Desert

Image credit: Center for Genome Regulation

Over the past three years our group has identified 62 different plant species that inhabit the Atacama Desert, and established a correlation between their habitat attributes and biological characteristics. Using tools such as whole transcriptome shotgun sequencing or RNA-Seq complemented with different bioinformatics approaches, we have identified over 896,000 proteins that are expressed in these conditions.

In this way we aim to learn which processes are highly utilized in these “extreme survivors” compared to similar species that are present in the deserts of California, where the climatic conditions are similar but there is no nitrogen scarcity. That is how we expect to find new mechanisms (or, more precisely, very old mechanisms) that enable plants to survive and grow efficiently in extreme environments.


 
Susana Cabello

Dr Susana Cabello

Written by Dr Susana Cabello, Center for Genome Regulation, Millennium Nucleus for Plant Systems and Synthetic Biology, Chile. Susana would like to acknowledge Maite Salazar & Rodrigo Gutierrez for their suggestions and edits.

Increasing Food Production in a Changing World

The fifth report of the International Panel on Climate Change (IPCC) published last year announced that climate change is already negatively affecting our food supply and this problem is only going to be amplified in coming decades.

Our climate is projected to warm by 5ºC by 2050, with increased incidence of extreme weather events. Coinciding with this is a rapidly rising global population, predicted to reach 9.6 billion by 2050. Feeding all these extra mouths is challenge enough. Doing this under changing weather and climate conditions becomes even more difficult.

Food shortages resulting from population growth or unusual weather events can lead to rising food prices and political instability. A global rice shortage in 2008 saw prices rise by over 50%, resulting in riots in Asia and Africa. We might expect events such as this to become more common in the future as the food supply becomes more and more affected by climate change.

Not surprisingly food security is currently a buzz word in the research community, and many resources are being poured into trying to ensure a stable food supply for future generations.

Some climate skeptics argue that increases in carbon dioxide could boost plant growth, resulting in higher yielding plants under climate change. However, the reality is that any positive effect the increased CO2 could have on plant growth is likely to be outweighed by higher temperatures and extreme weather events.

Since the IPCC report there have been a number of studies focussed on the staple food crop wheat, and how yields could be affected in the future.

Wheat

Wheat was first domesticated 10,000 years ago and is now grown more widely than any other crop. Photo by jayneandd used under CC BY 2.0.

Wheat yields are sensitive to temperature, and are predicted to fall by around 6% for every 1ºC rise in temperature. If we do not cut down current emissions, the earth could warm by 5ºC by 2050, equating to a 30% reduction in wheat yields due to temperature increases alone.

This 30% reduction in yield is only the tip of the iceberg. Yields could be further reduced by increased instances of disease epidemics. For example, Fusarium Ear Blight is a wheat disease that causes spikelet bleaching and enhanced senescence. A severe epidemic can wipe out 60% of a wheat crop. In order to take effect, the disease requires wet weather at flowering, something which we can expect to happen more often in the future according to climate models.

Extreme weather events, such as flooding, are predicted to increase over the coming decades, and will cause unavoidable crop losses. This will exacerbate problems with declining yields, further increasing the difficulty of feeding a growing population.

What can we do?

Primarily, we should be trying to limit the extent of climate change, and to do so we need to act now. Reducing emissions and moving to sustainable energy sources should be at the top of the agenda.  However, most climate scientists agree that even if we act now to reduce our emissions, there will be at least 2ºC of warming, which is already impacting on food production.

We therefore need to make our food sources more resilient to climate change. In terms of wheat this means breeding varieties that are tolerant to higher temperatures and diseases. Additionally, we will need to adapt our farming methods, to be more intensive yet sustainable, and perhaps alter our diets.

Stress Resilience Forum, 23–25 October, Iguassu Falls, Brazil

In October the Global Plant Council, in collaboration with the Society of Experimental Biology, will bring together experts from around the world to discuss current research efforts in plant stress resilience. Abstract submission and registration for the Stress Resilience Forum is now open, and we welcome researchers at all levels to take part.

The meeting takes place immediately before the International Plant Molecular Biology Conference (25–30 October), also at Iguassu Falls, and which also includes several scientific sessions on plant stresses.

The Nature of Crop Domestication

Why do we eat some plants but not others? What makes a good crop, and how have we transformed these species to suit our own needs?

Around 12,000 years ago, humans began to transition from nomadic hunter-gatherer societies to a more settled agricultural life. We began to selectively breed cereals and other crops to improve desirable traits, such as their yields, taste and seed retention. Today we eat less than 1% of all flowering plant species, relying on a handful of staples for almost all of our calories.

Why do we eat so few plant species?

Professor John Warren, Aberystwyth University

Professor John Warren, Aberystwyth University

We spoke with Professor John Warren at Aberystwyth University in the UK, who delves into the history of crop domestication in his new book, ‘The Nature of Crops: How We Came to Eat the Plants We Do,’ published on 24th April 2015. He blogs about how we came to eat certain plants over at Pick of the Crop, and said that his book developed from there. “The stories of crop domestication are just so interesting, weird, biologically strange, fun – they just demand to be told,” he enthused.

So why do we eat so few of the edible plants in the world? Based on his research into gene flow and plant breeding systems, Professor Warren presents novel theories in his book: “Previously people have argued that it’s because most plant are poisonous, but I don’t think that holds water. We actively seek out toxic plants as crops; plants with large food stores tend to be well defended with toxins. Instead I argue that it’s plant sexual habits that limit crop domestication. Plants with the usual pollination mechanisms don’t make ideal crops as they will fail to set seed when grown on an agricultural scale. Thus we domesticate things that are wind pollinated or pollinated by common generalist insects.”

Science-led crop breeding

Why do we eat poisonous plants?

How did our ancestors come to realise that rhubarb leaves are poisonous but the stems make a tasty crumble? Professor Warren says, “Its discovery was an accident and a fairly recent one – but read the book for the full story.” Image credit: Cory Doctorow used under CC BY-SA 2.0.

Professor Warren works at the Institute of Biological, Environmental and Rural Sciences (IBERS) at Aberystwyth University, which houses much of the research into agriculture and the environment that ties into the theme of his book. “Previously it’s been argued that there haven’t really been any new crops in the last 5,000 years. Here in Aberystwyth, we know that ryegrass, clover, elephant grass and others are still in the process of being domesticated, so you don’t need to be an archaeologist to study the process,” he explained. In addition to breeding new varieties of cereals and forage crops for food and feed, the Public Good Plant Breeding group at IBERS are also in the process of breeding Miscanthus, a fast-growing grass species that could be used for sustainable bioenergy in the future.

Resources like the Diversity Seek (DivSeek) initiative, established by the Global Plant Council in association with the Global Crop Diversity Trust, the CGIAR Consortium and the Secretariat of the International Treaty on Plant Genetic Resources for Food and Agriculture, could be used to enable science-driven crop breeding and domestication. DivSeek aims to unlock the genetic diversity that is currently stored in genebanks around the world by using cutting edge sequencing, phenotyping and ‘big data’ technologies. The genetic variation that is identified can then be used as the basis for breeding programs and could assist in the domestication of novel crops.

The future of agriculture

Drought damage

Drought damage in California, 2014. Image credit: US Department of Agriculture used under CC BY 2.0.

The crops we eat today were domesticated in highly fertile conditions; this means they are nutritious but tend to demand a high input of fertilizers and water. Professor Warren argues that we can use modern science to develop more sustainable ways to feed the global population: “It’s important that we start to think outside the box and try and domesticate a whole range of new crops that are more sustainable and less demanding of agricultural inputs.” An important source of future crop species could be stress-tolerant plants living in difficult environments: “I think the crops of the future could still be waiting to be domesticated from plants growing in harsh conditions,” explained Professor Warren.

Professor Warren also discussed how we could use underutilized crops in new ways to make agriculture more sustainable in the future: “I think and hope that we will eat more species, and that we will grow many more of these as perennials in poly-culture systems. That makes ecological sense in terms of niche exploitation and yield sustainability. It also makes more genetic sense in terms of resistance to pests and diseases.” The only downside, he said, is that these systems are so different to what we have now that we will need innovative research to develop them.


About Professor John Warren

Akee fruit

The akee is the national fruit of Jamaica. Image credit: Loren Sztajler, used under CC BY-ND 2.0.

John is a plant ecologist at Aberystwyth University, UK, with research interests in the origin and maintenance of diversity and enhancement of conservation value, particularly within agricultural ecosystems. He is the Director of Teaching and Learning and a Professor of Botany in the Institute of Biological, Environmental and Rural Sciences. John says the strangest plant he’s ever eaten is the akee, a plant beloved of Jamaicans that looks and tastes a bit like scrambled eggs but which is delicious with saltfish.


Over to you

What do you think will be the most important crops of tomorrow, and which underutilized plants will become dietary staples in an effort to feed the world more sustainably?

Can you crowdfund the sequencing of a plant genome?

Dr Peng Jiang, University of Georgia, USA

Dr Peng Jiang, University of Georgia, USA

Peng Jiang and Hui Guo at the University of Georgia think you can! They are currently raising money via a crowdfunding approach to sequence the first cactus genome – but the question is: why would they want to? Peng explains all in this guest blog post.

A Prickly Proposal: Why Sequence the Cactus?
In these times of growing food insecurity due to climate change and population pressures, the prickly pear cactus (Opuntia ficus) has growing commercial and agricultural importance across much of the world – you will find it growing in Mexico and Brazil, Chile, large parts of India and South Africa, and in Spain and Morocco.

The goal of our proposal is to sequence the genome and transcriptome of the prickly pear cactus, a recognized food and forage crop in these challenging semiarid regions of the world.

With more than 130 genera and 1,500 species of Cactaceae, we will create a draft genomic and transcriptome database that would aid the understanding of this understudied plant family, and provide the research community with valuable resources for molecular breeding and genetic manipulation purposes. Here are some of the reasons why we think a first cactus genome would be so important:

The Prickly Pear Cactus

The Prickly Pear Cactus

1. Ecological Improvement
The beauty of the drought-tolerance cactus is that it can grow on desert-like wastelands. Nowadays, more than 35% of the earth’s surface is arid or semiarid, making it inadequate for most agricultural uses. Without efforts to curb global warming, “Thermageddon” may hit in 30–40 years time, causing desertification of the US, such that it may become like the Sahara. Opuntia helps create a vegetative cover, which improves soil regeneration and rainfall infiltration into the soil. This cactus genome research may help us to adapt our food crops to a much hotter, drier climate.

2. Food Crops, Feed and Medicine
The fruits of prickly pear cactus are edible and sold in stores under the name “tuna”. Prickly pear nectar is made with the juice and pulp of the fruits. The pads of prickly pears (“Nopalito”) are also eaten as a vegetable. Both the fruits and pads of prickly pears can help keep blood sugar levels stable because they contain rich, soluble fibers. The fruit contains vitamin C and was used as an early cure for scurvy.

Furthermore, there has been much medical interest in the prickly pear plant. Studies [1, 2, 3] have shown that the pectin contained in prickly pear pulp lowers cholesterol levels. Another study [4] found that the fibrous pectin in the fruit may lower a diabetic’s need for insulin. The plant also contains the antioxidant flavonoids quercetin, (+)-dihydroquercetin (taxifolin), quercetin 3-methyl ether (isorhamnetin) and kaempferol, which have a protective function against the DNA damage that leads to cancer.

3. Biofuels in Semiarid Regions
Planting low water use, Crassulacean acid metabolism (CAM; a water saving mode of photosynthesis) biofuel feedstocks on arid and semiarid lands could offer immediate and sustained biogas advantages. Opuntiapads have 8–12% dry matter, which is ideal for anaerobic digestion. With an arid climate, this prevents the need for extra irrigation or water to facilitate the anaerobic digestion process. Requiring only 300 mm of precipitation per year, Opuntiacan produce a large amount of dry matter feedstock and still retain enough moisture to facilitate biogas production. It’s possible to get as much as 2.5 kWh of methane from 1 kg of dry Opuntia.

4. Phylogenetic Importance
Trained botanists and amateurs alike have held cacti in high regard for centuries. The copious production of spines, lack of leaves, bizarre architecture and impressive ability to persist in the harshest environments on Earth are all traits that have entitled this lineage to be named a true wonder of the plant world.

The cacti are one of the most celebrated radiations of succulent plants. There has been much speculation about their age, but progress in dating cactus origins has been hindered by the lack of fossil data for cacti or their close relatives. Through whole genome sequencing, we help will reveal the genomic evolution of Opuntia by comparing this genome with that of other sequenced plant species.

Cacti are typical CAM plants. We will analyse the evolution of CAM genes in the cactus to help reveal the secret of drought tolerance. Furthermore, plant architecture genes and MADS-box gene family members will be analysed to reveal the specific architecture and structure of cactus.

Crowdfunding the Cactus Genome Project
Cactus has several fascinating aspects that are worth exploring, not just for its biology, but also its relevance to humanity and the global environment. We plan to generate a draft genome for Opuntia, and have launched a crowdfunding campaign to help fund this project – we have already raised $2300 USD (46% of what we need), but we only have 15 days to raise the rest. If you would like to help fund this project, please visit our Experiment page at: https://experiment.com/projects/sequencing-the-cactus-genome-to-discover-the-secret-of-drought-resistance.

If we are successful in raising enough money to initiate the Cactus Genome Project, not only will this be the first plant genome to be sequenced in the Cactaceae family, we will be releasing the results to the plant science community through GeneGarden, an ornamental plant genome database. Our citizen science approach is also allowing us to reach out directly to members of the public, creating exciting opportunities for outreach and engagement with plant science.

If you have any further questions, please contact project leader Dr Peng Jiang at [email protected].

This blog post is slightly adapted from a post originally appearing on GigaScience Journal’s GigaBlog. Reproduced and adapted with permission, under a CC-BY license.

References

  1. Wolfram RM, Kritz H, Efthimiou Y, et al. Effect of prickly pear (Opuntia robusta) on glucose- and lipid-metabolism in non-diabetics with hyperlipidemia – a pilot study. Wien Klin Wochenscr. 2002;114(19–20):840–6.
  2. Trejo-Gonzalez A, Gabriel-Ortiz G, Puebla-Perez AM, et al. A purified extract from prickly pear cactus (Opuntia fulignosa) controls experimentally induced diabetes in rats. J Ethnopharmacol. 1996;55(1):27–33.
  3. Fernandez ML, Lin EC, Trejo A, et al. Prickly pear (Opuntia sp.) pectin alters hepatic cholesterol metabolism without affecting cholesterol absorption in guinea pigs fed a hypercholesterolemic diet. J Nutr. 1994;124(6):817–24.
  4. Frati-Munari AC, Gordillo BE, Altamirano P, et al. Hypoglycemic effect of Opuntia streptacantha Lemaire in NIDDM. Diabetes Care. 1988:11(1):63–66.

Cellulosic Ethanol from Sugarcane in Brazil

sugarcane fieldBrazil is a major producer of ethanol from sugarcane, and this leading global position is the fruit of scientific and technological advances resulting from a development program that was initiated in the 1970s. Driven by the oil crises of 1972-1973, Brazil transformed several sugar mills into ethanol producing units that became capable of co-production of ethanol and raw sugar (5). This was technically possible due to the high levels of sucrose in sugarcane and to the development of yeast strains capable of fermenting this sugar efficiently. At the same time, the first automobiles running exclusively on ethanol were introduced, which on the one hand helped Brazil face major world energy crises, and on the other implanted the basis for development of future technologies. Over the following 40 years, Brazilian sugar mills undertook a technological transformation that significantly increased the efficiency of sucrose and alcohol production. This method, now called first generation (1G), has reached a level of 90% conversion of sucrose into ethanol (5). At the same time, advances in sugarcane agricultural technology improved the sugarcane crop to a high level of productivity (averaging 80 tones per hectare). Using intensive breeding programs, a number of sugarcane varieties have been developed that are increasingly better adapted to the diverse climate and soils encountered in Brazil. The result is that Brazil is now the second largest producer of ethanol and the first placed producer of sugarcane in the world.

The necessity to produce second-generation ethanol

Until 2006, Brazil was the only country to produce and use ethanol on a large scale as a fuel alternative for cars. Since then, increased public awareness and governmental focus around the world on issues related to climate change and the excessive use of fossil fuels has led to increased interest in the use of renewable energy. It was at this moment that Brazil, with its highly efficient sugarcane bioethanol sector, became a leader worldwide in the production and use of renewable energy. Nevertheless, production of 1G bioethanol was already at the limit of efficiency both from industrial and agronomical viewpoints.

It was in this context that the Brazilian scientific community and the Federal and State of São Paulo governments took the initiative in the search for ways to increase production of sugarcane ethanol beyond current limits. An idea that was already being revived in several places in the world was the possibility to produce ethanol from sugar polymers, including cellulose, present in cell walls of plants. This search for ‘cellulosic ethanol’ is generally referred to as second-generation (2G) ethanol. Although establishment of 1G technology was highly successful, the potential for ethanol production from 2G is much higher because energy accumulated in sugarcane in the form of sucrose represents only 1/3 of the total. The other two-thirds are distributed equally between the bagasse (stems) and the leaves.

Cell wall recalcitrance

At first sight, the idea of producing ethanol from biomass seems straightforward: it would be enough to convert cellulose to free sugars that could be fermented by yeast. Although many advances have been made in this area, this problem is far from being solved, and developing 2G processes that are economically viable has proven to be a major challenge. The plant cell wall is composed mainly of carbohydrates in the form of polysaccharides that associate to form a supramolecular structure where polymers aggregate through non-covalent linkages. Some polysaccharides are branched with phenolic compounds (ferulic an p-coumaric acids). Ferulic acid can dimerize interlocking polysaccharide chains or these can still undergo polymerization with other phenylpropanoids, including p-hydrocinammic, sinapyl and coniferyl alcohols, forming lignin. Together, the supramolecular structure of cell-wall polymers constitute the main obstacle to enzymatic hydrolysis. Furthermore, known hydrolytic enzymes have molecular sizes that prevent their penetration into the polymer matrix. Therefore, when a mixture of enzymes is added to the surface of the cell wall, the catalytic attack is mainly on the surface of the composite. To perform more complete hydrolysis, enzymatic complexes would have to act in a synergetic fashion on the entire cell wall composite. At present this is not feasible as researchers cannot adequately control the process because very little is known about the synergism between the enzymes involved. One of the principal limitations to understand such mechanisms is that until recently our knowledge of the structure and architecture of the sugarcane cell wall was very limited.

Sugarcane buckAt the biological level, cell wall recalcitrance in plants is thought to be due to the wall’ ability to protect against herbivores and the penetration of pathogens. At the molecular level, the cell wall of sugarcane presents three domains of polysaccharides that interact through non-covalent linkages: the pectic domain, the hemicellulosic domain and the cellulosic domain. The cellulosic domain is embedded within the hemicellulosic domain and both are embedded in the pectin domain. Thus, the basic unit of the cell wall of sugarcane consists of a core with macrofibrils (agglomerated of microfibrils) of cellulose strongly linked to structurally complex hemicelluloses that display a glycomic code, the complex branching pattern of these compounds (2). In addition, this core of polysaccharides is surrounded by an agglomerate of polymers that interact with themselves. Phenolic compounds are also thought to interlock the three polysaccharide domains so that the covalent linkages are protected, effectively sealing the whole unit and creating a structure that is extremely resistant to mechanical, chemical and biochemical degradation.

Several publications produced by the research labs of the National Institute of Science and Technology of Bioethanol (INCT-Bioetanol – www.inctdobioetanol.com.br) have demonstrated that it is possible to disassemble the cell wall using chemical reagents (4). The procedure consists of initially attacking the phenolic compounds and eliminating them from the wall. This makes subsequent separation of the wall polysaccharides possible via treatment with a series of alkali solutions of increasing concentration (6).

A procedure called pretreatment (chemical and physical treatments with hot water, ammonia, acids and/alkali), eliminates the porosity barrier so that all polymers become accessible to attack by hydrolases. However, the branching nature of hemicelluloses still acts as a barrier and prevents further enzyme attack of the polymer chains. This highlights the necessity of using specific enzymatic complexes in order to produce free sugars that can be utilized for fermentation (1-7). As branched hemicelluloses alter the way polysaccharides are recognized by enzymes, their branching pattern (glycomic code) can alter the interaction between enzyme and substrate, affecting enzyme kinetics and cell wall degradation efficiency. The available data shows that the cell wall of sugarcane displays at least 18 glycosidic linkages, and suggests that approximately the same number of enzymes will be necessary to degrade the cell wall completely (5,6). Nevertheless, this chemical process is extremely complicated, laborious and expensive, and this is therefore not a viable strategy for industry.

The collection of enzymes characterized during the first phase of the INCT-Bioetanol contains practically all the catalytic capabilities needed for complete sugarcane cell wall hydrolysis. For this reason, the Institute has reached a point of prioritizing experiments focused on combining enzymes, forming consortia capable of dealing with each of the limiting factors related to recalcitrance. The possible combinations of enzymes have been proposed (1,6) and during the next phase of the project, these strategies will be put into practice by an integrated group of researchers in a series of experiments that will test this hypothesis.

At the same time, it will be necessary to understand the variability in the structure of the sugarcane cell wall in order to find Brazilian sugarcane varieties possessing structures and architectures that are more amenable to hydrolysis. Although the variation in cell wall composition is relatively limited among sugarcane tissues, one may expect to find considerable variation among the great number of extant varieties. This has been recently observed for Miscanthus and maize, two grass species that are genetically related to sugarcane and with very similar cell walls. Several research groups have concentrated efforts on understanding the role of lignin in recalcitrance and have concluded that this interference is somewhat limited. The reduction in lignin content leads in general to an increase in saccharification in a non-linear fashion depending on the pre-treatment, morphological distribution and the level of lignin aggregation (9), suggesting that other cell wall domains make equally important contributions to the recalcitrance of biomass. Research groups of the INCT-Bioetanol have already obtained transformed sugarcane in which the gene encoding one of the enzymes of lignin biosynthesis (COMT) has been silenced. These transgenic plants have cell walls that are modified, and saccharification tests are currently in progress. During the second phase of the INCT we intend to verify whether such genetic variability also exists in sugarcane and to use this information to obtain varieties in which differences among cell wall composition lead to lower recalcitrance to hydrolysis.

 

Marcos S. Buckeridge

[email protected]

Laboratory of Plant Physiological Ecology, Depatment of Botany, Institute of Biosciences, University of São Paulo (www.lafieco.com.br)

Director of the National Institute of Science and Technology of Bioethanol (www.inctdobioetanol.com.br)

 

REFEFENCES

  1. Buckeridge, M.S., Dos Santos,W.D., Tiné, M.A.S., De Souza, A.P. (2015) Compendium of Bioenergy Crops: Sugarcane edited by Eric Lam. CRC Press, Taylor and Francis (in press)
  2. Buckeridge, M.S. & De Souza, A.P. (2014) Breaking the “glycomic code” of cell wall polysaccharides may improve second generation bioenergy production from biomass. Bioenergy Research DOI 10.1007/s12155-014-9460-6
  3. Buckeridge, M.S.; Souza, A.P.; Arundale, R.A.; Anderson-Teixeira, K.J.; DeLucia, E. (2012) Ethanol from sugarcane in Brazil: a “midway” strategy for increasing ethanol production while maximizing environmental benefits. GCB Bioenergy, 4:119-126.
  4. Buckeridge, M. S. (Org.) ; Goldman, G. H. (Org.) . Routes to cellulosic ethanol. 1. ed. Nova Iorque: Springer, 2011. v. 1. 263p.
  5. De Souza, A. P. ; Grandis, A. ; Leite, D. C. C. ; Buckeridge, M.S. (2014) Sugarcane as a Bioenergy Source: History, Performance, and Perspectives for Second-Generation Bioethanol. Bioenerg Res, 7:24-35.
  6. De Souza, A. P., Leite, D. C. C., Pattathil, S. ; Hahn, M. G. ; Buckeridge, M. S. (2013) Composition and Structure of Sugarcane Cell Wall Polysaccharides: Implications for Second-Generation Bioethanol Production. Bioenergy Research, 6: 564-579.
  7. Mccann, M. ; Buckeridge, M. S. ; Carpita, N.C. . Plants and Bioenergy. 1. ed. New York: Springer, 2013. v. 1. 300p.
  8. Magrin, G.O., J.A. Marengo, J.-P. Boulanger, M.S. Buckeridge, E. Castellanos, G. Poveda, F.R. Scarano, and S. Vicuña, 2014: Central and South America. In: Climate Change 2014: Impacts, Adaptation, and Vulnerability. Part B: Regional Aspects. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Barros, V.R., C.B. Field, D.J. Dokken, M.D. Mastrandrea, K.J. Mach, T.E. Bilir, M. Chatterjee,K.L. Ebi, Y.O. Estrada, R.C. Genova, B. Girma, E.S. Kissel, A.N. Levy, S. MacCracken, P.R. Mastrandrea, and L.L. White (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. XXX-YYY
  9. Rezende, C.A.; Lima, M.; Maziero, P.; Azevedo, E.; Garcia, W.; Polikarpov, I. (2011) Chemical and morphological characterization of sugarcane bagasse submitted to a delignification process for enhanced enzymatic digestibility. Biotechnology for Biofuels. 4: 54