Striga hermonthica – a beautiful but devastating plant…

This week’s post was written by Caroline Wood, a PhD candidate at the University of Sheffield.

When it comes to crop diseases, insects, viruses, and fungi may get the media limelight but in certain regions it is actually other plants which are a farmer’s greatest enemy. In sub-Saharan Africa, one weed in particular – Striga hermonthica – is an almost unstoppable scourge and one of the main limiting factors for food security.

Striga is a parasitic plant; it attaches to and feeds off a host plant. For most of us, parasitic plants are simply harmless curiosities. Over 4,000 plants are known to have adopted a parasitic mode of life, including the seasonal favorite mistletoe (a stem parasite of conifers) and Rafflesia arnoldii, nicknamed the “corpse flower” for its huge, smelly blooms. Although the latter produces the world’s largest flower, it has no true roots – only thread-like structures that infect tropical vines.

When parasitic plants infect food crops, they can turn very nasty indeed. Striga hermonthica is particularly notorious because it infects almost every cereal crop, including rice, maize, and sorghum. Striga is a hemiparasite, meaning that it mainly withdraws water from the host (parasitic plants can also be holoparasites, which withdraw both water and carbon sugars from the host). However, Striga also causes a severe stunting effect on the host crop (see Figure 1), reducing their  yield to practically nothing. Little wonder then, that the common name for Striga is ‘witchweed’.

Striga-infected sorghum

Figure 1: Striga-infected sorghum. Note the withered, shrunken appearance of the infected plants. Image credit: Joel Ransom.

 

Several features of the Striga lifecycle make it especially difficult to control. The seeds can remain dormant for decades and only germinate in response to signals produced by the host root (called strigolactones) (Figure 2). Once farmland becomes infested with Striga seed, it becomes virtually useless for crop production. Germination and attachment takes place underground, so the farmer can’t tell if the land is infected until the parasite sends up shoots (with ironically beautiful purple flowers). Some chemical treatments can be effective but these remain too expensive for the subsistence farmers who are mostly affected by the weed. Many resort to simply pulling the shoots out as they appear; a time-consuming and labor-intensive process. It is estimated that Striga spp. cause crop losses of around US $10 billion each year [1].

Certain crop cultivars and their wild relatives show natural resistance to Striga. Here at the University of Sheffield, our lab group (headed by Professor Julie Scholes) is working to identify resistance genes in rice and maize, with the eventual aim of breeding these into high-yielding cultivars. To do this, we grow the host plants in rhizotrons (root observation chambers) which allow us to observe the process of Striga attachment and infection (see Figure 3). Already this has been successful in identifying rice cultivars that have broad-spectrum resistance to Striga, and which are now being used by farmers across Africa.

 

Life cycle of Striga

Figure 2: Life cycle of Striga spp. A single plant produces up to 100,000 seeds, which can remain viable in the soil for 20 years. Following a warm, moist conditioning phase, parasite seeds become responsive to chemical cues produced by the roots of suitable hosts, which cause them to germinate and attach to the host root. The parasite then develops a haustorium: an absorptive organ which penetrates the root and connects to the xylem vessels in the host’s vascular system. This fuels the development of the Striga shoots, which eventually emerge above ground and flower. Figure from [2].

 

But many fundamental aspects of the infection process remain almost a complete mystery, particularly how the parasite overcomes the host’s intrinsic defense systems. It is possible that Striga deliberately triggers certain host signaling pathways; a strategy used by other root pathogens such as the fungus Fusarium oxysporum. This is the focus of my project: to identify the key defense pathways that determine the level of host resistance to Striga. It would be very difficult to investigate this in crop plants, which typically have incredibly large genomes, so my model organism is Arabidopsis thaliana, the workhorse of the plant science world, whose genome has been fully sequenced and mapped. Arabidopsis cannot be infected by Striga hermonthica but it is susceptible to the related species, Striga gesnerioides, which normally infects cowpea.  I am currently working through a range of different Arabidopsis mutants, each affected in a certain defense pathway, to test whether these have an altered resistance to the parasite.  Once I have an idea of which plant defense hormones may be involved (such as salicylic acid or jasmonic acid), I plant to test the expression of candidate genes to decipher what is happening at the molecular level.

Striga-infected Arabidopsis

Figure 3: One of my Arabidopsis plants growing in a rhizotron. Preconditioned Striga seeds were applied to the roots three weeks ago with a paintbrush. Those that successfully attached and infected the host have now developed into haustoria. The number of haustoria indicates the level of resistance in the host. Image credit: Caroline Wood.

 

It’s early days yet, but I am excited by the prospect of shedding light on how these devastating weeds are so effective in breaking into their hosts. Ultimately this could lead to new ways of ‘priming’ host plants so that they are armed and ready when Striga attacks. It’s an ambitious challenge, and one that will certainly keep me going for the remaining two years of my PhD!

 

You can follow my journey by reading my blog and keeping up with me on Twitter (@sciencedestiny).

 

References:

[1] Westwood, J. H. et al. (2010). The evolution of parasitism in plants. Trends in Plant Science, 15(4): 227-235.

[2] Scholes, J. D. and Press, M. C. (2008). Striga infestation of cereal crops – an unsolved problem in resource limited agriculture. Current Opinion in Plant Biology, 11(2): 180-186.

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.

Student-driven plant breeding symposium addresses global challenges in the 21st century

This week we spoke to Francisco Gomez and Ammani Kyanam, graduate students in the Soil and Crop Science Department at Texas A&M University, USA. They were part of the organizing committee for the recent Texas A&M Plant Breeding Symposium, a successful meeting run entirely by students at the University.

Francisco Gomez and Ammani Kyanam

Francisco Gomez and Ammani Kyanam, part of the student organizing committee of the Plant Breeding Symposium

Could you begin with a brief introduction to the Plant Breeding Symposium held at Texas A&M in February?

Texas A&M University is one of the largest academic and public plant breeding institutions worldwide, which trains breeders in a variety of programs. Every year, students at the University organize the Texas A&M Plant Breeding Symposium, which is part of the DuPont Pioneer series of symposia. The symposium provides a platform for graduate students to bridge the interaction between the public and private sectors and engage in conversations about the grand challenges facing humanity that could be addressed by plant breeding. It’s also a great chance to network with faculty, students, and industry representatives.

 

Could you tell us more about this theme and how the different sessions were chosen?

We wanted the theme of the meeting to mirror the university’s goal of thinking big to pinpoint solutions to modern global challenges using plant science and breeding. Every member of the committee had the opportunity propose a theme, which were then put to a vote.

Nikolai Vavilov

Nikolai Vavilov, a Russian botanist and geneticist, was the inspiration for this year’s symposium. Image credit: Public Domain.

This year’s theme, “The Vavilov Method: Utilizing Genetic Diversity”, celebrated the life and career of Russian botanist Nikolai Vavilov, who identified the centers of origin of cultivated plants. We invited plant scientists and breeders who are applying Vavilov’s ideas through the conservation, collection, and effective utilization of genetic diversity in modern crop breeding programs. This year we also developed a workshop entitled “Where does a breeder go to find genetic diversity?”, which allowed students and faculty to talk about the importance of utilizing genetic diversity in crop improvement and to learn new tools to help them incorporate genetic diversity in breeding programs.

 

Could you tell us more about how you developed the workshop?

Our aim for the workshop was to engage students and faculty on where we can find genetic diversity, how we can use it, and to include a panel discussion on the challenges and the future of genetic diversity in modern plant breeding programs. As a new value-added event, the workshop was challenging to set up because it required a different set of skills to the rest of the meeting. Once we had an idea of what we wanted, we set up an initial meeting with our speakers where we brainstormed ideas. After several online meetings and e-mails with Professor Paul Gepts (UC Davis), Dr. Colin Khoury (Agricultural Research Service, USDA; check out his recent GPC blog here!), and Professor Susan McCouch (Cornell University), we finalized the structure of the workshop, the layout of the sessions, and the objectives for the speakers. We also had a representative from DivSeek, Dr. Ruth Bastow, on the discussion panel, who contributed to our discussion on future tools for accessing diversity in the future.

 

How has the symposium grown since the inaugural meeting in 2015?

Every year we want to make the symposium a memorable event, and we want other students and faculty to really get something out of it. We are learning more and more about the students and faculty with these events, particularly in terms of which topics are the most exciting or interesting. The symposium has also grown into a two-day event, with this year’s inclusion of the workshop.

 

Did you have to overcome any challenges in the organization of the event?

One of our biggest challenges was to secure funding for the event, which is free to attend. To add further value to our event, we wanted to have additional components such as a student research competition and/or workshop, which meant we had to aggressively fundraise from multiple sources. This involved writing a lot of grant proposals both to plant sciences departments across Texas A&M University, as well as to other sources of external funding.

We are grateful to DuPont Pioneer for providing a large amount of the funding. In 2017, we also received sponsorship from the Texas Institute for Genomic Science and Society, Departments of Soil and Crop Sciences, Molecular and Environmental Plant Science, Horticulture, Plant Pathology, and Biology, Texas Grain Sorghum Association, Texas Peanut Producers Board, and Cotton Incorporated. Our beverage sponsor was Pepsi and Kind Snacks was our snack sponsor.

 

What advice would you give a graduate student trying to organize a similar event?

Plan early and set small goals! Communication is key for a large team to organize such an event. We encourage groups to use Slack or some sort of team work interface. It really helped us to be in constant communication with each other during the months leading up to the symposium.

 

Could you tell us a little about your own research?

My research (Francisco Gomez) is focused on identifying genomic regions (known as quantitative trait loci; QTLs) associated with mechanical traits that are known to be associated with stem lodging, a major agronomic problem that reduces yields worldwide. My colleague and co-chair, Ammani Kyanam, received her Masters in Plant Breeding in while working in the cotton cytogenetics program in our department. Her research focused on developing genomic tools to facilitate the development of Chromosome Segment Substitution Lines for upland cotton. She is currently mapping QTLs for aphid resistance in sorghum for her Ph.D. You can learn more about the research of our individual committee members at http://plantbreedingsymposium.com/committee/.

 

How can our readers connect with you?

We have a strong social media presence via Facebook, Instagram and YouTube, where we post event videos, photos and periodical updates. Check them out below!

Facebook: TAMUPBsymposium

Instagram: @pbsymposium

Twitter: @pbsymposium

YouTube: Texas A&M Plant Breeding Symposium

Website: plantbreedingsymposium.com

Email: mailto:[email protected]

Just add water: Could resurrection plants help feed the world?

This week we spoke to Professor Henk Hilhorst (Wageningen University and Research) about his research on desiccation tolerance in seeds and plants.

 

Could you begin by telling us a little about your research?

I am a plant physiologist specializing in seed biology. I have a long research record on various aspects of seeds, including the mechanisms and regulation of germination and dormancy, desiccation tolerance, as well as issues in seed technology. Being six years from retirement now, I decided to extend my desiccation tolerance studies from seeds to resurrection plants, which display vegetative desiccation tolerance. I strongly believe that unveiling of the mechanism of vegetative desiccation tolerance may help us create crops that are truly tolerant to severe drought, rather than (temporarily) resistant.

 

How did you become interested in this field of study, and how has your career progressed?

As with many things in life, it was coincidence. I majored in plant biochemistry and applied for a PhD position in seed biology. After obtaining the degree I was offered a tenure track position in seed physiology by the Laboratory of Plant Physiology at Wageningen University, where I still work as a faculty member. My career has progressed nicely and I am an authority in the field of seed science, editor-in-chief of the journal Seed Science Research, and will become the President of the International Society for Seed Science in September of this year.

I see my current work on vegetative desiccation tolerance as a highlight in my professional life. I have always been more interested in the desiccation tolerance of seeds until about five years ago, when my current collaborator Prof Jill Farrant of the University of Cape Town, South-Africa, made me enthusiastic about these wonderful resurrection plants. We started to work together and published our first study recently in Nature Plants.

Read the paper here ($): A footprint of desiccation tolerance in the genome of Xerophyta viscosa.


 

In your recent paper, you sequenced the genome of the resurrection plant, Xerophyta viscosa, which can survive with less than a 5% relative water content. How is it possible for a plant to lose so much of its water and still survive?

These plants have a lot of characteristics that we’ve seen in seeds. They display protective desiccation tolerance mechanisms in their leaves, including anti-oxidants, protective proteins, and even dismantle their photosynthetic machinery during periods of drought. Even the cell wall structure and composition of resurrection plants resemble those of seeds. We are currently working on a paper describing the striking similarities between seeds and resurrection plants.

 

What was the most interesting discovery you made upon sequencing the genome of the resurrection plant?

First, the similarities between resurrection plants and seeds listed above were also apparent at the molecular level. For example, previous work suggested that the “ABI3 regulon”, consisting of about 100 genes regulated by the transcription factor ABI3, is specific to seeds, but we found that it is almost completely present (and active) in the leaves of Xerophyta viscosa too!

Secondly, we found “islands” or clusters of genes specific for desiccation tolerance that aren’t found in other species. Many of these regulate secondary metabolite pathways.

 

How challenging was it to sequence the genome of this plant? How did you overcome any difficulties?

It was very challenging. First, the species is an octoploid, meaning it has eight copies of each chromosome. This meant that we had to sequence its genome at very high coverage and employing the most advanced sequencing facilities, e.g. PacBio. Getting funding for this complex analysis was another challenge. We then took almost a year to assemble the genome and annotate it at the desired quality.

 

Xerophyta viscosa

Xerophyta viscosa before and after the rains. Image credit: Prof. Henk Hilhorst.

 

You identified some of the most important genes involved in desiccation tolerance. Is it possible to translate this work into other species, such as crops that may be threatened by drought as the climate changes?

That will be our ultimate goal. It’s important to remember that desiccation-sensitive plants, including all our major crops, produce seeds that are desiccation tolerant. This implies that the information for desiccation tolerance is present in the genomes of these crops but that it is only turned on in the seeds. We are trying to determine how this is localized, in order to find a method to turn on the desiccation tolerance mechanism in vegetative parts of the (crop) plant too. In parallel we are expressing some of the key transcription factors from Xerophyta viscosa in some important crops to see how this affects them.

 

Are there any other interesting aspects of Xerophyta viscosa biology?

Contrary to plants that wilt and ultimately die because of (severe) drought, leaves of resurrection species do not show such stress-related senescence. This is related to the engagement of active anti-senescence genes during the drying of the leaves of resurrection species. We are currently investigating these senescence-related mechanisms too.

 

Rose of Jericho (Anastatica hierochuntica)

The rose of Jericho (Anastatica hierochuntica) is another resurrection plant. Image credit: FloraTrek. Used under license: CC BY-SA 3.0.

 

Do you expect to find that different types of desiccation-tolerant plants use the same subset of genes to survive drought, or could they have developed other pathways to resilience?

We expect that the core mechanism is very similar among the resurrection species but that each species may have adapted to its specific environment.

Funding permitting, we will sequence the genomes of at least another ten resurrection species to further clarify the various evolutionary pathways to desiccation tolerance and, importantly, to discriminate between species-specific and desiccation tolerance-specific genes.

 

What advice do you have for early career researchers?

Stick to what you believe in, even if you have to (temporarily) be involved in research that you appreciate less, e.g., because of better funding opportunities.

 


Read Henk’s recent paper in Nature Plants here ($): A footprint of desiccation tolerance in the genome of Xerophyta viscosa.

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.

Roots of a second green revolution

This week we spoke to Professor Jonathan Lynch, Penn State University, whose research on root traits has deepened our understanding of how plants adapt to drought and low soil fertility.

 

 

Could you begin by giving us a brief introduction to your research?

We are trying to understand how plants adapt to drought and low soil fertility. This is important because all plants in terrestrial ecosystems experience suboptimal water and nutrient availability, so in rich nations we maintain crop yields with irrigation and fertilizer, which is not sustainable in the long term. Furthermore, climate change is further degrading soil fertility and increasing plant stress. This topic is therefore both a central question in plant evolution and a key challenge for our civilization. We need to develop better ways to sustain so many people on this planet, and a big part of that will be developing more resilient, efficient crop plants.

 

Drought is devastating for crops

Drought and low soil fertility are devastating for crops. Image credit: CIAT. Used under license: CC BY-SA 2.0.

 

What got you interested in this field, and how has your career developed over time?

When I was 9 years old I became aware of a famine in Africa related to crop failure and resolved to do something about it. I studied soils and plant nutrition as an undergraduate, and in graduate school worked on plant adaptation to low phosphorus and salinity stress, moving to a research position at the CIAT headquarters in Colombia. Later I moved to Penn State, where I have maintained this focus, working to understand the stress tolerance of staple crops, and collaborating with crop breeders in the USA, Europe, Africa, Asia, and Latin America.

 

Your recent publications feature a variety of different crop plants. Could you talk about how you select a species to study?

We work with species that are important for food security, that grow in our field environments, and that I think are cool. We have devoted most of our efforts to the common bean – globally the most important food legume – and maize, which is the most important global crop. These species are often grown together in Africa and Latin America, and part of our work has been geared to understanding how maize/bean and maize/bean/squash polycultures perform under stress. These are fascinating, beautiful plants with huge cultural importance in human history. They are also supported by talented, cooperative research communities. One nice feature of working with food security crops is that their research communities share common goals of achieving impact to improve human welfare.

 

Common bean (Phaseolus vulgaris)

The common bean (Phaseolus vulgaris) is an important staple in many parts of the world. Image credit: Ervins Strauhmanis. Used under license: CC BY 2.0.

 

Many researchers use Arabidopsis thaliana for plant research, but are crops better suited for root research than the delicate roots of Arabidopsis? Are crop plants more or less difficult to work with in your research than Arabidopsis?

The best research system is entirely a function of your goals and questions. We have worked with Arabidopsis for some questions. Since we work with processes at multiple scales, including crop stands, whole organisms, organs, tissues, and cells, it has been useful to work with large plants such as maize, which are large enough to easily measure and to work with in the field. The most interesting stress adaptations for crop breeding are those that differ among genotypes of the same species, and at that level of organization there is a lot of biology that is specific to that species, that cannot readily be generalized from model organisms with very different life strategies. There has been considerable attention to model genomes and much less attention to model phenomes.

 

You have developed methodologies for the high-throughput phenotyping of crop plants. What does this technique involve and what challenges did you have to overcome to succeed?

We have developed multiple phenotyping approaches – too many to summarize readily here. Our overall approach is simply to develop a tool that helps us achieve our goals. For example, we have developed tools to quantify the root architecture of thousands of plants in the field, to measure anatomical phenotypes of thousands of samples from field-grown roots, to help us determine which root phenotypes might affect soil resource capture, etc. Working with geneticists and breeders, we are constantly asked to measure something meaningful on thousands of plants in a field, in many fields, every season. ARPA-E (the US Advanced Research Projects Agency for Energy) has recently funded us to develop phenotyping tools for root depth in the field, but this is the first time we have been funded to develop phenotyping tools – generally we just come up with things to help us do our work, which fortunately have been useful for other researchers as well.

 

Could you talk about some of the computational models you have developed for investigating plant growth and development?

The biological interactions between plants and their environment are so complex, we need computational (in silico) tools to help us evaluate them. Increasingly, in silico tools can integrate information across multiple scales, from gene expression to crop stands. These tools also allow us to evaluate things that are difficult to measure, such as phenotypes that do not yet exist, or future climates. In silico biology will be an essential tool in 21st Century biology, which will have access to huge amounts of data at multiple scales that can be used to try to understand incredibly complex systems, such as the human brain or roots interacting with living soil. Our main in silico tool is SimRoot, developed over the past 25 years to understand how root phenotypes affect soil resource capture.

Check out a SimRoot model below:


 

You have been working on breeding plants that have improved yield in soils with low fertility. What have you achieved in this work?

In collaboration with crop breeders and colleagues in various nations we have developed improved common bean lines with better yield under drought and low soil fertility that are being deployed in Africa and Latin America, improved soybean lines with better yield in soils with low phosphorus being deployed in Africa and Asia, and are now working with maize breeders in Africa to develop lines with better yield under drought and low nitrogen stress. Many crop breeders are using our methods for root phenotyping to target root phenotypes in their selection regimes in multiple crops.

 

What piece of advice do you have for early career researchers?

You are at the forefront of an unprecedented challenge we face as a species – how to sustain 10 billion people in a degrading environment. Plant biologists are an essential part of the effort to reshape how we live on this planet. Do not doubt the importance of your efforts. Do not lose sight of the very real human impact of your scientific choices. Do not be deterred by the gamesmanship and ‘primate politics’ of science. You can make a difference. We need you.

Creole maize reveals adaptation secrets

By Lucina Melesio

[MEXICO CITY] An international team of scientists identified a hundred genes that influence adaptation to the latitude, altitude, growing season and flowering time of nearly 4,500 native maize varieties in Mexico and in almost all Latin American and Caribbean countries.

Creole — or native — varieties of maize are derived from improvements made over thousands of years by local farmers, and contain genes that help them adapt to different environments.

“We are now using this analysis to find other genes that are of vital importance to breeders, such as those resistant to extreme heat, frost or drought — environmental conditions associated with climate change and that could affect maize production.”

Sarah Hearne, CIMMYT

“Latin American breeders will be able to use these results to identify native varieties that could contribute to improved adaptation”, Edward Buckler, a Cornell University researcher and co-author of the study published in Nature Genetics (February 6), told SciDev.Net.

The information on the genetic markers described in the study will be available online, said Sarah Hearne, a researcher at the International Maize and Wheat Improvement Center (CIMMYT) and co-author of the study. “Meanwhile, any breeder can contact us to request information”, she said.

“We are now using this analysis to find other genes that are of vital importance to breeders, such as those resistant to extreme heat, frost or drought — environmental conditions associated with climate change and that could affect maize production”, Hearne said.

Maize ears from CIMMYT’s collection, showing a wide variety of colors and shapes. CIMMYT’s germplasm bank contains about 28,000 unique samples of cultivated maize and its wild relatives, teosinte and Tripsacum. These include about 26,000 samples of farmer landraces—traditional, locally-adapted varieties that are rich in diversity. The bank both conserves this diversity and makes it available as a resource for breeding.
Photo credit: Xochiquetzal Fonseca/CIMMYT.

Studying native maize varieties is extremely difficult because of their genetic variation. Although domesticated, they are wilder than commercial varieties.

For this study, the researchers cultivated hybrid creole varieties in various environments in Latin America and identified regions of the genome that control growth rates. They looked into where the varieties came from and what genetic features contributed to their growth in that environment.

 In comments to SciDev.Net, James Holland, a researcher at North Carolina State University, Jeffrey Ross-Ibarra, a researcher at the University of California Davis, and Rodomiro Ortiz, a researcher at the Swedish University of Agricultural Sciences — who did not participate in the study — commended the magnitude of the study and the original method developed by the researchers to access the rich set of genetic information about native maize varieties.

Hearne added that the research team has initiated a “pre-breeding” programme with a small group of breeders in Mexico. As part of that programme, CIMMYT delivers to breeders materials from its germplasm bank of Creole maize; it also provides molecular information the breeders can use to generate new varieties.

This piece was produced by SciDev.Net’s Latin America and Carribean edition.

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

Global Plant Council stress resilience commentaries published in Food and Energy Security

In October 2015, researchers from around the world came together in Iguassu Falls, Brazil, for the Stress Resilience Symposium, organized by the Global Plant Council and the Society for Experimental Biology (SEB), to discuss the current research efforts in developing plants resistant to the changing climate. (See our blog by GPC’s Lisa Martin for more on this meeting!)

Building on the success of the meeting, the Global Plant Council team and attendees compiled a set of papers to provide a powerful call to action for stress resilience scientists around the world to come together to tackle some of the biggest challenges we will face in the future. These four papers were published in the Open Access journal Food and Energy Security alongside an editorial about the Global Plant Council.

In the editorial, the Global Plant Council team (Lisa Martin, Sarah Jose, and Ruth Bastow) introduce readers to the Global Plant Council mission, and describe the Stress Resilience initiative, the meeting, and introduce the papers that came from it.

In the first of the commentaries, Matthew Gilliham (University of Adelaide), Scott Chapman (CSIRO), Lisa Martin, Sarah Jose, and Ruth Bastow discuss ‘The case for evidence-based policy to support stress-resilient cropping systems‘, commenting on the important relationships between research and policy and how each must influence the other.

Global Plant Council President Bill Davies (Lancaster University) and CIMMYT‘s Jean-Marcel Ribaut outline the ways in which research can be translated into locally adapted agricultural best practices in their article, ‘Stress resilience in crop plants: strategic thinking to address local food production problems‘.

In the next paper, ‘Harnessing diversity from ecosystems to crops to genes‘, Vicky Buchanan-Wollaston (University of Warwick), Zoe Wilson (University of Nottingham), François Tardieu (INRA), Jim Beynon (University of Warwick), and Katherine Denby (University of York) describe the challenges that must be overcome to promote effective and efficient international research collaboration to develop new solutions and stress resilience plants to enhance food security in the future.

University of Queensland‘s Andrew Borrell and CIMMYT‘s Matthew Reynolds discuss how best to bring together researchers from different disciplines, highlighting great examples of this in their paper, ‘Integrating islands of knowledge for greater synergy and efficiency in crop research‘.

In all of these papers, the authors suggest practical short- and long-term action steps and highlight ways in which the Global Plant Council could help to bring researchers together to coordinate these changes most effectively.

Read the papers in Food and Energy Security here.