Reflections from the “Feed the Future” conference in Burkina Faso

By Atsuko Kanazawa, Igor Houwat, Cynthia Donovan

This article is reposted with permission from the Michigan State University team. You can find the original post here: MSU-DOE Plant Research Laboratory

By Atsuko Kanazawa

Atsuko Kanazawa is a plant scientist in the lab of David Kramer. Her main focus is on understanding the basics of photosynthesis, the process by which plants capture solar energy to generate our planet’s food supply.

This type of research has implications beyond academia, however, and the Kramer lab is using their knowledge, in addition to new technologies developed in their labs, to help farmers improve land management practices.

One component of the lab’s outreach efforts is its participation in the Legume Innovation Lab (LIL) at Michigan State University, a program which contributes to food security and economic growth in developing countries in Sub-Saharan Africa and Latin America.

Atsuko recently joined a contingent that attended a LIL conference in Burkina Faso to discuss legume management with scientists from West Africa, Central America, Haiti, and the US. The experience was an eye opener, to say the least.

To understand some of the challenges faced by farmers in Africa, take a look at this picture, Atsuko says.

Rows of corn crops in Burkina Faso

Corn crops in Burkina Faso. By Atsuko Kanazawa

“When we look at corn fields in the Midwest, the corn stalks grow uniformly and are usually about the same height,” Atsuko says. “As you can see in this photo from Burkina Faso, their growth is not even.”

“Soil scientists tell us that much farmland in Africa suffers from poor nutrient content. In fact, farmers sometimes rely on finding a spot of good growth where animals have happened to fertilize the soil.”

Even if local farmers understand their problems, they often find that the appropriate solutions are beyond their reach. For example, items like fertilizer and pesticides are very expensive to buy.

That is where USAID’s Feed the Future and LIL step in, bringing economists, educators, nutritionists, and scientists to work with local universities, institutions, and private organizations towards designing best practices that improve farming and nutrition.

Atsuko says, “LIL works with local populations to select the most suitable crops for local conditions, improve soil quality, and manage pests and diseases in financially and environmentally sustainable ways.”

Unearthing sources of protein

At the Burkina Faso conference, the Kramer lab reported how a team of US and Zambian researchers are mapping bean genes and identifying varieties that can sustainably grow in hot and drought conditions.

The team is relying on a new technology platform, called PhotosynQ, which has been designed and developed in the Kramer labs in Michigan.

A user testing a plant leaf with the MultispeQ

PhotosynQ in action: the device collects data. A mobile app  uploads it to an online platform for further analysis. By Harley J Seeley Photography

PhotosynQ includes a hand-held instrument that can measure plant, soil, water, and environmental parameters. The device is relatively inexpensive and easy to use, which solves accessibility issues for communities with weak purchasing power.

The heart of PhotosynQ, however, is its open-source online platform, where users upload collected data so that it can be collaboratively analyzed among a community of 2400+ researchers, educators, and farmers from over 18 countries. The idea is to solve local problems through global collaboration.

Atsuko notes that the Zambia project’s focus on beans is part of the larger context under which USAID and LIL are functioning.

“From what I was told by other scientists, protein availability in diets tends to be a problem in developing countries, and that particularly affects children’s development,” Atsuko says. “Beans are cheaper than meat, and they are a good source of protein. Introducing high quality beans aims to improve nutrition quality.”

Science alone is sometimes not enough

But, as LIL has found, good science and relationships don’t necessarily translate into new crops being embraced by local communities.

Farmers might be reluctant to try a new variety, because they don’t know how well it will perform or if it will cook well or taste good. They also worry that if a new crop is popular, they won’t have ready access to seed quantities that meet demand.

Sometimes, as Atsuko learned at the conference, the issue goes beyond farming or nutrition considerations. In one instance, local West African communities were reluctant to try out a bean variety suggested by LIL and its partners.

The issue was its color.

“One scientist reported that during a recent famine, West African countries imported cowpeas from their neighbors, and those beans had a similar color to the variety LIL was suggesting. So the reluctance was related to a memory from a bad time.”

This particular story does have a happy ending. LIL and the Burkina Faso governmental research agency, INERA, eventually suggested two varieties of cowpeas that were embraced by farmers. Their given names best translate as, “Hope,” and “Money,” perhaps as anticipation of the good life to come.

A gathering at a women's experimental farm.

Visiting the women-run farms. By Atsuko Kanazawa

 

Another fruitful, perhaps more direct, approach of working with local communities has been supporting women-run cowpea seed and grain farms. These ventures are partnerships between LIL, the national research institute, private institutions, and Burkina Faso’s state and local governments.

Atsuko and other conference attendees visited two of these farms in person. The Women’s Association Yiye in Lago is a particularly impressive success story. Operating since 2009, it now includes 360 associated producing and processing groups, involving 5642 women and 40 men.

“They have been very active,” Atsuko remarks. “You name it: soil management, bean quality management, pest and disease control, and overall economic management, all these have been implemented by this consortium in a methodical fashion.”

“One of the local farm managers told our visiting group that their crop is wonderful, with high yield and good nutrition quality. Children are growing well, and their families can send them to good schools.”

As the numbers indicate, women are the main force behind the success. The reason is that, usually, men don’t do the fieldwork on cowpeas. “But that local farm manager said that now the farm is very successful, men were going to have to work harder and pitch in!”

Back in Michigan, Atsuko is back to the lab bench to continue her photosynthesis research. She still thinks about her Burkina Faso trip, especially how her participation in LIL’s collaborative framework facilitates the work she and her colleagues pursue in West Africa and other parts of the continent.

“We are very lucky to have technologies and knowledge that can be adapted by working with local populations. We ask them to tell us what they need, because they know what the real problems are, and then we jointly try to come up with tailored solutions.”

“It is a successful model, and I feel we are very privileged to be a part of our collaborators’ lives.”

This article is reposted with permission from the Michigan State University team. You can find the original post here: MSU-DOE Plant Research Laboratory

Taking the brakes off plant production: not so good after all

Reposted with kind permission from the MSU-DOE Plant Research Laboratory. Original article.

By: Igor Houwat, Atsuko Kanazawa, David Kramer

The need for speed: increasing plant yield is one way to increase food and fuel resources. But asking plants to simply do more of the usual is a strategy that can backfire. Photo by Romain Peli on Unsplash

When engineers want to speed something up, they look for the “pinch points”, the slowest steps in a system, and make them faster.

Say, you want more water to flow through your plumbing. You’d find the narrowest pipe and replace it with a bigger one.

Many labs are attempting this method with  photosynthesis, the process that plants and algae use to capture solar energy.

All of our food and most of our fuels have come from photosynthesis. As our population increases, we need more food and fuel, requiring that we improve the efficiency of photosynthesis.

But, Dr. Atsuko Kanazawa and the Kramer Lab are finding that, for biological systems, the “pinch point” method can potentially do more harm than good, because the pinch points are there for a reason!  So, how can this be done?

 

ATP synthase: an amazing biological nanomachine

Atsuko and her colleagues at the MSU-DOE Plant Research Laboratory (PRL) have been working on this problem for over 15 years. They have focused on a tiny machine in the  chloroplast called the  ATP synthase, a complex of proteins essential to storing solar energy in “high energy molecules” that power life on Earth.

That same ATP molecule and a very similar ATP synthase are both used by animals, including humans, to grow, maintain health, and move.

In plants, the ATP synthase happens to be one of the slowest process in photosynthesis, often limiting the amount of energy plants can store.

Photosynthetic systems trap sunlight energy that starts the reaction to move electrons forward in an assembly-line fashion to make useful energy compounds. The ATP synthase is one of the “pinch points” that slows the flow as needed, so plants stay healthy. In cfq, the absence of feedback leads to an electron pile up at PSI, and a crashed system. By MSU-DOE Plant Research Laboratory, except tornado graphic/CC0 Creative Commons

 

Kicking up the gears of plant production

Atsuko thought, if the ATP synthase is such an important pinch point, what happens if it were faster? Would it be better at photosynthesis and give us faster growing plants?

Years ago, she got her hands on a mutant plant, called cfq, from a colleague. “It had an ATP synthase that worked non-stop, without slowing down, which was a curious example to investigate. In fact, under controlled laboratory conditions – very mild and steady light, temperature, and water conditions – this mutant plant grew bigger than its wild cousin.”

But when the researchers grew the plant under the more varied conditions it experiences in real life, it suffered serious damage, nearly dying.

“In nature, light and temperature quality change all the time, whether through the passing hours, or the presence of cloud cover or winds that blow through the leaves,” she says.

 

Plants slow photosynthesis for a reason!

Recent innovations from the Kramer lab are enabling Atusko and her colleagues to probe into how real environmental conditions affect plant growth.

Atsuko’s research now shows that the slowness of the ATP synthase is not an accident; it’s an important braking mechanism that prevents photosynthesis from producing harmful chemicals, called reactive oxygen species, which can damage or kill the plant.

“It turns out that sunlight can be damaging to plants,” says Dave Kramer, Hannah Distinguished Professor and lead investigator in the Kramer lab.

“When plants cannot use the light energy they are capturing, photosynthesis backs up and toxic chemicals accumulate, potentially destroying parts of the photosynthetic system. It is especially dangerous when light and other conditions, like temperature, change rapidly.”

“We need to figure out how the plant presses on the brakes and tune it so that it responds faster…”

The ATP synthase senses these changes and slows down light capture to prevent damage. In that light, the cfqmutant’s fast ATP is a bad idea for the plant’s well-being.

“It’s as if I promised to make your car run faster by removing the brakes. In fact, it would work, but only for a short while. Then things go very wrong!” Dave says.

“In order to improve photosynthesis, what we need is not to remove the brakes completely, like in cfq, but to control them better,” Dave says. “Specifically, we need to figure out how the plant presses on the brakes and tune it so that it responds faster and more efficiently,” David says.

Atsuko adds: “Scientists are trying different methods to improve photosynthesis. Ultimately, we all want to tackle some long-term problems. Crucially, we need to continue feeding the Earth’s population, which is exploding in size.”

The study is published in the journal, Frontiers in Plant Science.

 

Potatoes, allies on Earth and on Mars

By
Zoraida Portillo (Perú)

[LIMA] A joint initiative between NASA and the International Potato Centre (CIP), which is based in Peru, offers scientific evidence that it is possible to grow at least four types of potatoes on Mars.

A scenario starring the root crop was portrayed in the movie “The Martian” (2015), in which a lost astronaut, played by Matt Damon, survives on potatoes he cultivates on the red planet while awaiting rescue.

But in addition to this interplanetary possibility, scientists also observed the crop is genetically suited to adapting to the changes creating more adverse environmental conditions on Earth.

So before turning fiction into reality, the tuber has a mission on Earth.

papa-en-marte-1-pelicula1.jpg

In the movie “The Martian”, Matt Damon survives eating the potatoes he cultivates on Martian soil. Credit: 20th Century Fox.

The hardy potato quartet
papa-en-marte-2-CIP.jpg

Scientists have studied 65 types of potatoes and have identified four that could grow successfully on Martian soil. Credit: International Potato Center / Mars Project

The study has identified four types of potatoes, out of 65 examined, which have shown resistance to high salinity conditions and were able to form tubers in a type of soil similar to that on Mars.
One of these is the Tacna variety, developed in Peru in 1993. It was introduced to China shortly afterwards, where it showed high tolerance to droughts and saline soils with hardly any need for irrigation.

This variety became so popular in China that it was ‘adopted’ in 2006 under the name of Jizhangshu 8. The same high tolerance was seen on the saline and arid soils of Uzbekistan, a country with high temperatures and water shortages, where the variety was also introduced and renamed as Pskom.

papa-en-marte-3-tacna in china.jpg

In China, the Peruvian Tacna potato variety was renamed Jizhangshu 8. Credit: International Potato Center 

The second variety that passed the salinity test is being cultivated in coastal areas of Bangladesh that have high salinity soils and high temperatures. The other two types are promising clones — potatoes that are being tested for attributes that would make them candidates for becoming new varieties.

These four potato types were created as a result of the CIP’s breeding programme to encourage adaptation to conditions in subtropical lowlands, such as extreme temperatures, which are expected to be strongly affected by climate change.

papa-en-marte-4-bangladesh.jpg

Women harvest resistant potatoes in saline soils in Bangladesh. Credit: International Potato Center

Down to Earth

In addition to these four potato ‘finalists’, other clones and varieties have shown promising results when tested in severe environmental conditions. The findings offer researchers new clues about the genetic traits that can help tubers cope with severe weather scenarios on Earth.

papa-en-marte-5-walter amoros by zp.JPG

Walter Amorós, CIP’s potato breeder is one of the five researchers involved in the project. Credit: Zoraida Portillo

“It was a pleasant surprise to see that the potatoes that we have improved to tolerate adverse conditions were able to produce tubers on this soil [soil similar to that on Mars],” says Walter Amorós, CIP potato breeder and one of the five researchers involved in the project, who has studied potatoes for more than 30 years.

According to Alberto García, adviser to the UN Food and Agriculture Organization in Peru who is in charge of food security programmes, this experiment “serves to verify that potato, a produce of great nutritional value, is a crop extremely adaptable to the worst conditions”, something that is very relevant for current climate scenarios.

García stresses that global temperatures are now rising at a rate higher than expected, affecting not only potatoes but also other crops. Many now need to be cultivated at higher altitudes — which, he says, is not always a disadvantage and may even be beneficial for crops that were previously cultivated in valleys.

papa-en-marte-7-by ZP.jpg

Credit: Zoraida Portillo

“But it can also have negative consequences that we have to anticipate,” adds García. Therefore, he says this experiment can inspire others to think about future scenarios and look for other crops than can adapt to extreme conditions that will have an impact on agriculture.

Similar to Mars

The project began with a search for soils similar to that found on Mars. Julio Valdivia-Silva, a Peruvian researcher who worked at NASA’s Ames Research Center, eventually concluded that the soil samples collected in the Pampas de la Joya region of southern Peru were the most similar to Martian soil.

papa-en-marte-8-julio Valdivia.jpg

Julio Valdivia-Silva took soil samples at Pampa de La Joya, Peru. Credit: NASA/ International Potato Center

Arid, sterile and formed by volcanic rocks, these soil samples were extremely saline.

papa-en-marte-9-roca en la joya.jpg

Credit: Pampas de La Joya Official Site

 

Helped by engineers from the University of Engineering and Technology (UTEC) in Lima and based on designs by NASA’s Ames Research Center, the CIP built CubeSat — a miniature satellite that recreates, in a confined environment, a Martian-like atmosphere. This is where the potatoes were cultivated.

papa-en-marte-10-cubosat.jpg

The varieties were cultivated inside CubeSat, built by the CIP to recreate environmental conditions similar to those on Mars. Credit: International Potato Center / Mars Project

“If potatoes could tolerate the extreme conditions to which we exposed them in our CubeSat, they have a good opportunity to develop on Mars,” says Valdivia-Silva.

They then conducted several rounds of experiments to find out which varieties could better withstand the extreme conditions, and what minimum conditions each crop needed to survive.

papa-en-marte-11-Tierra-Marte-suelos.jpg

La Joya desert, Peru (left); Martian soil (right). Credits: Pampas de La Joya Official Site and NASA, respectively.

CubeSat, hermetically sealed, housed a container with La Joya soil, where each one of the tubers was cultivated. CubeSat itself supplied water and nutrients, controlled the temperature according to that expected at different times on Mars, and also regulated the planet’s pressure, oxygen and carbon dioxide levels.

papa-en-marte-12-compu-CIP.jpg

Connected to a computer, the CubeSat supplied water and nutrients, and imitated other environmental conditions that would be found on Mars. Credit: International Potato Center / Mars Project

 

Cameras were installed to record the process, broadcasting developments on the soil and making it possible to see the precise moment in which potatoes sprouted.

Based on the results, CIP scientists say that in order to grow potatoes on Mars, space missions will have to prepare the soil so it has a loose structure and contains nutrients that allow the tubers to obtain enough oxygen and water.

In a next phase of the project, the scientists hope to expose successful varieties to more extreme environmental conditions. This requires, among other things, developing a prototype satellite similar to CubeSat that can replicate more extreme conditions with greater precision, at a price tag of US$ 100,000.

This piece was produced by SciDev.Net’s Latin America and Caribbean desk.

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

Fighting Fusarium wilt to beat the bananapocalypse

Dr. Sarah Schmidt (@BananarootsBlog), Researcher and Science Communicator at The Sainsbury Laboratory Science. Sarah got hooked on both banana research and science writing when she joined a banana Fusarium wilt field trip in Indonesia as a Fusarium expert. She began blogging at https://bananaroots.wordpress.com and just filmed her first science video. She speaks at public events like the Pint of Science and Norwich Science Festival.

 

Every morning I slice a banana onto my breakfast cereal.

And I am not alone.

Every person in the UK eats, on average, 100 bananas per year.

Bananas are rich in fiber, vitamins, and minerals like potassium and magnesium. Their high carbohydrate and potassium content makes them a favorite snack for professional sports players; the sugar provides energy and the potassium protects the players from muscle fatigue. Every year, around 5000 kg of bananas are consumed by tennis players at Wimbledon.

But bananas are not only delicious snacks and handy energy kicks. For around 100 million people in Sub-Saharan Africa, bananas are staple crops vital for food security. Staple crops are those foods that constitute the dominant portion of a standard diet and supply the major daily calorie intake. In the UK, the staple crop is wheat. We eat wheat-based products for breakfast (toast, cereals), lunch (sandwich), and dinner (pasta, pizza, beer).

In Uganda, bananas are staple crops. Every Ugandan eats 240 kg bananas per year. That is around 7–8 bananas per day. Ugandans do not only eat the sweet dessert banana that we know; in the East African countries such as Kenya, Burundi, Rwanda, and Uganda, the East African Highland banana, called Matooke, is the preferred banana for cooking. Highland bananas are large and starchy, and are harvested green. They can be cooked, fried, boiled, or even brewed into beer, so have very similar uses wheat in the UK.

In West Africa and many Middle and South American countries, another cooking banana, the plantain, is cooked and fried as a staple crop.

In terms of production, the sweet dessert banana we buy in supermarkets is still the most popular. This banana variety is called Cavendish and makes up 47% of the world’s banana production, followed by Highland bananas (24%) and plantains (17%). Last year, I visited Uganda and I managed to combine the top three banana cultivars in one dish: cooked and mashed Matooke, a fried plantain and a local sweet dessert banana!

 

Three types of banana in a single dish in Uganda.

Another important banana cultivar is the sweet dessert banana cultivar Gros Michel, which constitutes 12% of the global production. Gros Michel used to be the most popular banana cultivar worldwide until an epidemic of Fusarium wilt disease devastated the banana export plantations in the so-called “banana republics” in Middle America (Panama, Honduras, Guatemala, Costa Rica) in the 1950s.

Fusarium wilt disease is caused by the soil-borne fungus Fusarium oxysporum f. sp. cubense (FOC). The fungus infects the roots of the banana plants and grows up through the water-conducting, vascular system of the plant. Eventually, this blocks the water transport of the plant and the banana plants start wilting before they can set fruits.

Fusarium Wilt symptoms

Fusarium Wilt symptoms

The Fusarium wilt epidemic in Middle America marked the rise of the Cavendish, the only cultivar that could be grown on soils infested with FOC. The fact that they are also the highest yielding banana cultivar quickly made Cavendish the most popular banana variety, both for export and for local consumption.

Currently, Fusarium wilt is once again the biggest threat to worldwide banana production. In the 1990s, a new race of Fusarium wilt – called Tropical Race 4 (TR4) – occurred in Cavendish plantations in Indonesia and Malaysia. Since then, TR4 has spread to the neighboring countries (Taiwan, the Philippines, China, and Australia), but also to distant locations such as Pakistan, Oman, Jordan, and Mozambique.

Current presence of Fusarium wilt Tropical Race 4. Affected countries are colored in red.

In Mozambique, the losses incurred by TR4 amounted to USD 7.5 million within just two years. Other countries suffer even more; TR4 causes annual economic losses of around USD 14 million in Malaysia, USD 121 million in Indonesia, and in Taiwan the annual losses amount to a whopping USD 253 million.

TR4 is not only diminishing harvests. It also raises the price of production, because producers have to implement expensive preventative measures and treatments of affected plantations. These preventive measures and treatments are part of the discussion at The World Banana Forum (WBF). The WBF is a permanent platform for all stakeholders of the banana supply chain, and is housed by the United Nation’s Food and Agricultural Organization (FAO). In December 2013, the WBF created a special taskforce to deal with the threat posed by TR4.

Despite its massive impact on banana production, we know very little about the pathogen that is causing Fusarium wilt disease. We don’t know how it spreads, why the new TR4 is so aggressive, or how we can stop it.

Fusarium Wilt symptom

Fusarium Wilt symptoms in the discolored banana corm.

Breeding bananas is incredibly tedious, because edible cultivars are sterile and do not produce seeds. I am therefore exploring other ways to engineer resistance in banana against Fusarium wilt. As a scientist in the 2Blades group at The Sainsbury Laboratory, I am investigating how we can transfer resistance genes from other crop species into banana and, more recently, I have been investigating bacteria that are able to inhibit the growth and sporulation of F. oxysporum. These biologicals would be a fast and cost-effective way of preventing or even curing Fusarium wilt disease.

 

Twitter:           @BananarootsBlog

Email:              mailto:[email protected]

Website:          https://bananaroots.wordpress.com

Chinese plant science and Journal of Experimental Botany

Jonathan IngramThis week’s post was written by Jonathan Ingram, Senior Commissioning Editor / Science Writer for the Journal of Experimental Botany. Jonathan moved from lab research into publishing and communications with the launch of Trends in Plant Science in 1995, then going on to New Phytologist and, in the third sector, Age UK and Mind.

 

In this week of the XIXth International Botanical Congress (IBC) in Shenzhen, it seems appropriate to highlight outstanding research from labs in China. More than a third of the current issue of Journal of Experimental Botany is devoted to papers from labs across this powerhouse of early 21st century plant science.

Collaborations are key, and this was a theme that came up time again at the congress. The work by Yongzhe Gu et al. is a fine example, involving scientists at four institutions studying a WRKY gene in wild and cultivated soybean: in Beijing, the State Key Laboratory of Systematic and Evolutionary Botany at the Institute of Botany in the Chinese Academy of Sciences, and the University of the Chinese Academy of Sciences; and in Harbin (Heilongjiang), the Crop Tillage and Cultivation Institute at Heilongjiang Academy of Agricultural Sciences, and the College of Agriculture at Northeast Agricultural University. Interest here centers on the changes which led to the increased seed size in cultivated soybean with possible practical application in cultivation and genetic improvement of such a vital crop.

 

Crops and gardens

Botanic gardens are also part of the picture. In another paper in the same issue, Yang Li et al. from the Key Laboratory of Tropical Plant Resources and Sustainable Use at Xishuangbanna Tropical Botanical Garden in Kunming (Yunnan) and the University of the Chinese Academy of Sciences in Beijing present research on DELLA-interacting proteins in Arabidopsis. Here the authors show that bHLH48 and bHLH60 are transcription factors involved in GA-mediated control of flowering under long-day conditions.

IBC 2017

Naturally, research on rice is important. Wei Jiang et al. from the National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University (Wuhan) describe their research on WOX11 and the control of crown root development in the nation’s grain of choice, which will be important for breeders looking to increase crop yields and resilience.

The other work featured is either in Arabidopsis or plants of economic importance: Fangfang Zheng et al. (Qingdao Agricultural University, also with collaborators in Maryland) and Xiuli Han et al. (Beijing); Yun-Song Lai et al. (Beijing/Chengdu – cucumber), Wenkong Yao et al. (Yangling, Shaanxi – Chinese grapevine, Vitis pseudoreticulata), and Xiao-Juan Liu et al. (Tai-an, Shandong – apple).

 

Development of plant science

Shenzehn has grown rapidly and is now highly significant for life science as home to the China National GeneBank (CNGB) project led by BGI Genomics. The vision as set out by Huan-Ming Yang, chairman of BGI-Shenzhen, is profound – from sequencing what’s already here, often in numbers per species, to innovative synthetic biology.

Shenzehn is also home to another significant institution, the beautiful and scientifically important Fairy Lake Botanic Garden. At the IBC, the importance of biodiversity conservation for effective, economically focused plant science, but also for so many other reasons to do with our intimate relationship with plants and continued co-existence on the planet, was a central theme.

The research highlighted in Journal of Experimental Botany is part of the wider, positive growth of plant science (and, indeed, botany) not just in China, but worldwide. The Shenzehn Declaration on Plant Sciences with its seven priorities for strategic action, launched at the congress, will be a guide for the right development in coming years.

Genetics to boost sugarcane production

Scientists in Brazil are taking steps towards genetically modifying sugar cane so it produces more sucrose naturally, looking to eventually boost the productivity and economic benefits of the tropical grass.

A man stacks sugarcane at the Ver-o-Peso (Check the Weight) market in Belem.

Currently, it is common for producers to raise sucrose levels in sugar cane by applying artificial growth regulators or chemical ripeners. This inhibits flowering, which in turn prolongs harvest and milling periods.

One of these growth regulators, ethephon, is used to manage agricultural, horticultural and forestry crops around the world. It is widely used to manipulate and stimulate the maturation of sugarcane as it contains ethylene, which is released to the plant on spraying.

Ethylene, considered a ripening hormone in plants, contributes to increasing the storage of sucrose in sugar cane.

“Although we knew ethylene helps increase the amount of sugar in the cane, it was not clear how the synthesis and action of this hormone affected the maturation of the plant,” said Marcelo Menossi, professor at the University of Campinas (Unicamp) and coordinator of the project, which is supported by the Brazilian research foundation FAPESP.

To study how ethylene acts on sugarcane, the researchers sprayed ethephon and an ethylene inhibitor, aminoethoxyvinylglycine (AVG), on sugar cane before it began to mature.
sucrose accumulation.jpg

After spraying both compounds, they quantified sucrose levels in tissue samples from the leaves and stem of the cane. They did this five days after application and again 32 days later, on harvest.

Those plants treated with the ethephon ripener had 60 per cent more sucrose in the upper and middle internodes at the time of harvest, while the plants treated with the AVG inhibitor had a sucrose content that was lower by 42 per cent.

The researchers were then able to identify genes that respond to the action of ethylene during ripening of the sugar cane. They also successfully identified the genes involved in regulating sucrose metabolism, as well as how the hormone acts on sucrose accumulation sites in the plant.

Based on the findings, the team has proposed a molecular model of how ethylene interacts with other hormones.

“Knowing which genes or ripeners make it possible for the plant to increase the accumulation of sucrose will allow us to make genetic improvements in sugarcane and develop varieties that over-express these genes, without the need to apply ethylene, for example,” explained Menossi.

This research could also help with spotting the most productive sugar cane, as some varieties that do not respond well to hormones, he added. “It will be possible to identify those [varieties] that best express these genes and facilitate the ripening action.”

Taken from a newsletter by FAPESP, a SciDev.Net donor, edited by our Latin America and the Caribbean desk

 

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

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.

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.