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Beans: Sidestepping variety… to create varieties to combat drought, disease and pests

Africa, Beans, Crop breeding, Genetics, Genomics, Legumes No Responses »

Oct 302012

BREAK-TIME AND BRAKE-TIME from beans for a bit: Steve Beebe takes a pause to strike a pose in a bean field.

“These [molecular breeding] techniques, combined with conventional methods, shorten the time it takes to breed improved varieties that simultaneoulsy combine several traits.

And this means that we also get them out to farmers more quickly compared to phenotypic selection alone.”
– Steve Beebe

THE NEAR-PERFECT FOOD: Common beans (Phaseolus vulgaris L) comprise the world’s most important food legume, feeding about 200 million people in sub-Saharan Africa alone. Their nutritional value is so high, they have been termed ‘a near-perfect food’. They are also easy to grow, adapting readily to different cropping systems and maturing quickly.

That said, this otherwise versatile, adaptable and dapper dicotyledon does have some inherent drawbacks and ailments that crop science seeks to cure….

Rains are rapidly retreating, and drought doggedly advancing
Despite the crop’s widespread cultivation in Africa, “yields are low, stagnating at between 20 and 30 percent of their potential,” remarks Steve Beebe, GCP’s Product Delivery Coordinator for beans, and a researcher at the International Center for Tropical Agriculture (CIAT, by its Spanish acronym).

“The main problem is drought, brought about by climate change,” he says. “And it’s spreading – it already affects 70 percent of Africa’s major bean-producing regions.” Drought decimates bean harvests in most of Eastern Africa, but is particularly severe in the mid-altitudes of Ethiopia, Kenya, Tanzania, Malawi and Zimbabwe, as well as in southern Africa as a whole.

A myriad of forms and hues: bean diversity eloquently speaks for itself in this riot of colours.

Drought, doubt and duality − Diversity a double-edged sword
“Common beans can tolerate drought to some extent, using various mechanisms that differ from variety to variety,” explains Steve. But breeding for drought resistance is complicated by the thousands of bean varieties that are available. They differ considerably according to growth habit, seed colour, shape, size and cooking qualities, and cultivation characteristics.

“A variety might be fantastic in resisting drought,” says Steve, ‘but if its plant type demands extra work, the farmers won’t grow it,” he explains. “Likewise, if consumers don’t like the seed colour, or the beans take too long to cook, then they won’t buy.”

Molecular breeding deals a hand, waves a wand, and weaves a band
This is where molecular breeding techniques come in handy, deftly dealing with the complexities of breeding drought-resistant beans that also meet farmer and consumer preferences. No guesswork about it: molecular breeding rapidly and precisely gets to the heart of the matter, and helps weave all these different ‘strands’ together.

The bean research team has developed ‘genetic stocks’, or strains of beans that are crossed with the varieties favoured by farmers and consumers. The ‘crosses’ are made so that the gene or genes with the desired trait are incorporated into the preferred varieties.

The resulting new varieties are then evaluated for their performance in different environments throughout eastern and southern Africa, with particular focus on Ethiopia, Kenya, Malawi and Zimbabwe which are the target countries of the Tropical Legumes I (TLI) project.

Propping up the plant protein: a veritable tapestry of terraces of climbing beans.

GCP supported this foundation work to develop these molecular markers. This type of breeding – known in breeder parlance as marker-assisted selection (MAS) – was also successfully used to combine and aggregate resistance to drought; to pests such as bean stem maggot (BSM); and to diseases such as bean common mosaic necrosis potyvirus (BCNMV) and to bruchid or common bacterial blight (CBB). The resulting ‘combinations’ laden with all this good stuff were then bred into commercial-type bean lines.

“These techniques, combined with conventional methods, shorten the time it takes to breed improved varieties that simultaneoulsy combine several traits,” comments Steve. “This means that we also get them out to farmers more quickly compared to phenotypic selection alone.”

Informed by history and reality
Breeding new useful varieties is greatly aided by first understanding the crop’s genetic diversity, and by always staying connected with the reality on the ground: earlier foundation work facilitated by GCP surfaced the diversity in the bean varieties that farmers grow, and how that diversity could then be broadened with genes to resist drought, pests and disease.

What next?
Over the remaining two years of Phase II of the Tropical Legumes I (TLI) project, the bean team will use the genetic tools and breeding populations to incorporate drought tolerance into farmer- and market-preferred varieties. “Hence, productivity levels on smallholder farms are expected to increase significantly,” says Steve.

Partnerships
The work on beans is led by CIAT, working in partnership with Ethiopia’s South Agricultural Research Institute (SARI), the Kenya Agricultural Research Institute (KARI), Malawi’s Department of Agricultural Research and Technical Services (DARTS) and Zimbabwe’s Crop Breeding Institute (CBI) of the Department of Research and Specialist Services (DR&SS).

Other close collaborators include the eastern, central and southern Africa regional bean research networks (ECABREN and SABRN, their acronyms) which are components of the Pan-African Bean Research Alliance (PABRA). Cornell University (USA) is also involved.

VIDEO: Steve talks about what has been achieved so far in bean research, and what remains to be done

Links

VIDEO: The ABCs of bean breeding – Steve is joined by other bean breeding experts to discuss the basics of bean research
Bean research within the Legumes Research Initiative
Steve Beebe’s profile
BLOGPOSTS: Bean research in Ethiopia and Zimbabwe
OPEN ACCESS BOOK CHAPTER: How to phenotype beans for drought (by Steve Beebe et al)
Browse our searchable Product Catalogue for bean products by keying in ‘beans’ in the search panel
Bean facts and figures
Join the community of bean researchers
Making the business case for molecular breeding − an economic analysis in comparisoon with conventional breeding

TLI 2012: Bean research progress report from CGIAR Generation Challenge Programme

Chickpea research in Kenya – A boon for the fallow period

Africa, Chickpeas, Crop breeding, Legumes No Responses »

Jun 302012

“When we first started working on this project in mid-2007, our breeding programme was very weak,” says Paul Kimurto (pictured), Lead Scientist for chickpea research in the Tropical Legumes I (TLI) project, Kenya, and a lecturer in Crop Science at Egerton University.

“We have since accumulated a lot of germplasm, a chickpea reference set, and a mapping population, all of which have greatly boosted our breeding programme. From these, we have been able to select appropriate genotypes, and we obtained 400 breeding lines. None of this would have been directly possible without GCP’s support,” adds Paul. [Editor’s note: A ‘reference set’ is a sub-sample of existing germplasm collections that facilitates and enables access to existing crop diversity for desired traits, such as drought tolerance or resistance to disease or pests]

Due to their hardiness against drought, chickpeas have been steadily gaining popularity in Kenyan drylands – including the dry highlands – where they are grown as a ‘relay’ crop after wheat and maize harvests during the short rains, when the land would otherwise lie fallow. “Chickpeas have therefore increased food security and nutritional status of more than 27,000 households living in Baringo, Koibatek, Kerio Valley and Bomet Districts in Kenya, who frequently face hunger due to frequent crop failure of main staples such as maize and beans owing to climate change,” says Paul.

Chickpea adoption in these areas has increased due to close collaboration between GCP, ICRISAT and Egerton University through funding, training, resources and germplasm facilitated by GCP.

Exposure and capacity building
Through the project, various members of the Egerton research team have benefited from training in Europe, Africa and Asia on wide-ranging aspects of modern breeding, including data management. The learning resources that the team accesses through GCP are also shared widely and used as teaching materials and resources for faculty staff and postgraduate students not directly involved in the project.

“We have also benefitted from physical infrastructure such as a rain-shelter, irrigation system, laboratory equipment and a greenhouse. We didn’t have these, and probably couldn’t have had them, because all these are costly investments. This has greatly improved the efficiency of not only our research, but also our teaching,” says Paul. In addition, three postgraduate students are supported by GCP – two are pursuing PhDs and one a Masters, all using modern molecular breeding methods in their studies.

VIDEO: Paul discusses capacity building in Kenya, alongside other TLI colleagues

Community gains

Besides the university, capacity building has benefited the broader community: agricultural extension staff from the Ministry of Agriculture and from Koibatek Farmers Training Centre (one of the project’s research site), have been trained in various fields. The Centre manager attended a GCP course in Ghana tailored for research station staff (link below), as did an Egerton University technician.

In addition to aiding research trials, the irrigation system and weather station installed at Koibatek help with teaching and producing crop seed and planting materials as well as pasture for the community, since the Centre has a mandate to provide high-quality seed and livestock breeds to the community.

According to Beatrice Komen, a farmer in Koibatek, the irrigation system “has enabled the Agricultural Training Centre supply us with high-quality pasture and crop seeds for planting during the right time because Egerton University uses it to produce sufficient seed without having to rely on seasonal conditions.”

Paul adds, “The automated weather station is a first in the region.” The weather station also feeds regional data into the national meteorological database and is used for teaching by secondary schools in the community.

Going further, faster
Paul observes “With the direct funding we obtain through the project, we are able to expand into other areas of dryland research such as soil science and nitrogen fixation for chickpeas. Our efficiency has also increased: with the greenhouse and rainout shelter, we can now rapidly obtain generation crosses. And the irrigation system means we can now do off-season trials without having to wait for seasonal changes.”

“We have learnt a lot through our involvement with the Programme, including outsourcing of genotyping services which GCP fully supports, the advanced tools and wide range of services offered by the Integrated Breeding Platform for both breeding and data management,” says Paul. “We have also received digital tablet for electronic field data collection in a more efficient and accurate manner compared to the traditional pen and paper.”

The goal
“Our goal is to apply the modern breeding methods we have learnt to release new improved drought- and disease-resistant varieties before the project closes in mid-2014.” Some of these new methods include using quantitative trait loci (QTLs) through marker-assisted selection (MAS) and marker-assisted backcrossing (MABC).

“The results we obtain will provide foundation seed that can then be used for mass production through the Tropical Legumes II project,” says Paul.

“Our task is not complete until we have improved varieties in the hands of farmers,” he concludes.

VIDEO on farmer participation, and the relevance of genomics – Paul and TLI colleagues

Related links

OPEN ACCESS BOOK CHAPTER: How to phenotype chickpeas for drought
Chickpea research within the Legumes Research Initiative
Chickpea facts and figures
Join the chickpea community of practice
SEE IT IN PICTURES! VIDEO on progress in chickpea research and VIDEO on its impacts, and the relevance of genomics to farmers

TLI 2012: Data management for chickpea breeding – Kenya from CGIAR Generation Challenge Programme

Chickpea research in India – Getting to the root of the matter to enhance drought tolerance

Asia, Chickpeas, Crop breeding, Legumes No Responses »

Jun 272012

India is the world’s largest producer and consumer of chickpea, accounting for more than a third (66 percent) of world production.

The Indian Agricultural Research Institute (IARI) and the Indian Institute of Pulses Research (IIPR) are collaborating with the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) on marker-assisted backcrossing (MABC), to improve chickpeas for drought tolerance.

This complementary activity in the Tropical Legumes I project (TLI) Phase II is being funded by the Department of Biotechnology, Government of India.

Dr N Nadrajan (pictured left), IIPR Director, adds “We have been trained on the breeding tools offered by the Integrated Breeding Platform, including data management, and on electronic data collection using a handheld device.”

Shailesh Tripathi (pictured right) is a Senior Scientist working on chickpea breeding at IARI. “During Phase I of TLI, ICRISAT and its partners identified a root-trait QTL region which confers drought tolerance in chickpeas, and the markers by which to transfer this QTL region. By evaluating the chickpea reference set, ICRISAT and its partners in Africa identified about 40 lines for drought tolerance, and these lines are being used in Phase II of the project,” says Shailesh. [Editor’s note: A ‘reference set’ is a sub-sample of existing germplasm collections that facilitates and enables access to existing crop diversity for desired traits, such as drought tolerance or resistance to disease or pests]

“Through GCP, we have benefitted from training in molecular breeding. The benefits of this go beyond this project,” he adds.

The Indian scientists are using MABC as well as marker-assisted recurrent selection (MARS) in Phase II, applying genomic resources that came from Phase I of the project.

“Our goal is to obtain lines with good root traits for drought tolerance,” says Shailesh, realistically adding that “Variety release will take time, but the good news is that we already have the pre-release materials to identify donors for specific traits, like root biomass.”

Progress in chickpea research in Africa and Asia

Related links

OPEN ACCESS BOOK CHAPTER: How to phenotype chickpeas for drought
Chickpea research within the Legumes Research Initiative
Chickpea facts and figures
Join the chickpea community of practice

Chickpeas: Toughening a tough crop for tougher times by healing its Achilles’ heel

Africa, Chickpeas, Crop breeding, Legumes No Responses »

Jun 262012

It’s all about water and weakness – or strength. The Greek legend has it that Achilles was dipped into River Styx by his mother, Thetis, in order to make him invulnerable. His heel wasn’t covered by the water and he later died of the wound from an arrow that struck his heel.

In our times, this analogy can be applied to chickpeas, where this streetwise tough customer in the crop kingdom that thrives on the most rugged terrains is hamstrung if there is no rain at the critical grain-filling period – its sole Achilles’ heel, when it cannot take the searing heat in the drylands it otherwise thrives in.

But before you read on about the latter-day borrowing of this ancient legend, and science’s quest to heal the hit from heat and to cure the crop’s fatal flaw on water, first, an important aside…

Who’s now calling the shots in chickpea research?

Molecular breeding in Phase I was led by ICRISAT, with country partners in a supporting role. In Phase II, activities are being led by country partners, which also assures sustainability and continuity of the work. ICRISAT is now in a facilitating role, providing training and data, while the research work is now in the hands of country partners.” – Pooran Gaur, Principal Scientist: Chickpea Breeding, ICRISAT.

The facts
Chickpeas are an ancient crop that was first domesticated in central and western Asia. Today, this crop is cultivated in 40 countries and is second only to common beans as the food legume most widely grown by smallholders. The two main types of chickpeas – desi and kabuli – are valuable for both subsistence and cash.

Even for the hardy, times are tough
“Chickpeas are well-known to be drought-tolerant,” says Rajeev K Varshney, Principal Investigator of the project to improve chickpeas work in the Tropical Legumes I Project (TLI). He explains, “The plants are very efficient in using water and possess roots that seek out residual moisture in deeper soil layers.” However, he points out that, with changing climatic conditions, especially in drier areas, terminal drought – when rain does not fall during grain-filling – is the crop’s Achilles’ heel, and principal production constraint.

“Chickpeas are such tough plants that, even for conditions of terminal drought, yields can be increased by improving root characteristics and water-use efficiency,” says Rajeev. The research team has identified several lines with superior traits such as drought tolerance, after screening a set of 300 diverse lines selected based on molecular diversity of large germplasm collections.

VIDEO CLIP: Recipe for chickpea success

Enhancing the genetic makeup to beat the heat
The team went on to develop genomic resources such as molecular markers. With these markers, the team developed a high-density genetic map, and identified a genomic region containing several quantitative trait loci (QTLs), conferring drought tolerance. “QTLs help pinpoint, more specifically, the location of genes that govern particular traits like root length” explains Rajeev.

Longer roots will naturally give the plants a deeper reach into the water table. Root length is the difference between survival and perishing, which is why trees will be left standing on a landscape otherwise laid bare by prolonged drought.

Q for ‘quick’: QTLs speed things along from lab to field, and running with the winners
The discovery of QTLs makes identifying tolerant plants not only easier, but also cheaper and faster. “This means that better-adapted varieties will reach farmers faster, improving food security,” says Rajeev.

Pooran Gaur, GCP’s Product Delivery Coordinator for chickpeas, Principal Scientist for Chickpea Breeding at ICRISAT, and an important collaborator on the TLI project, adds, “We began marker-assisted selection backcrossing (MABC) in Phase I. By 2011, lines were already being evaluated in Ethiopia, India and Kenya. We are now at the stage of singling out the most promising lines.”

Putting chickpeas to the test: Rajeev Varshney (left) and Pooran Gaur (right) inspecting a chickpea field trial.

What was achieved in Phase I, and what outcomes are expected?
Phase I run from mid-2007 to mid-2010, during which time 10 superior lines for improved drought tolerance and insect resistance were identified for Ethiopia, Kenya and India. As well, a total of 1,600 SSR markers and 768 SNPs on GoldenGate assays were developed, along with an expanded DArT array with more than 15,000 features. A high-density reference genetic map and two intraspecific genetic maps were developed.

“We now have materials from marker-assisted backcrossing by using the genomic resources we produced in Phase I. These materials were sent to partners last year [2011]. And because in most cases we have the same people working in TLI as in TLII, this material is being simultaneously evaluated across six to seven locations by all TLI and TLII partners,” says Pooran.

“Preliminary analysis of data is quite encouraging and it seems that we will have drought-tolerant lines soon,” adds Rajeev.

Future work, and who’s now calling the shots in the field
In Phase II, 1,500 SNPs on cost-effective KASPar assays have been developed that have been useful to develop a denser genetic map. In collaboration with University of California–Davis (USA) and the National Institute of Plant Genome Research (India), a physical map has been developed that will help to isolate the genes underlying the QTL region for drought tolerance. A novel molecular breeding approach called marker-assisted recurrent selection (MARS) has been adopted. Over the remaining two years of Phase II, the chickpea work will focus on developing chickpea populations with superior genotypes for drought tolerance through MABC and MARS.

Pooran adds, “Molecular breeding in Phase I was led by ICRISAT, with country partners in a supporting role. In Phase II, activities are being led by country partners, which also assures sustainability and continuity of the work. ICRISAT is now in a facilitating role, providing training and data, while the MABC and MARS aspects are both in the hands of country partners.”

“Another important activity in Phase II is development of multi-parents advanced generation intercross (MAGIC) population that will help generation of genetic populations with enhanced genetic diversity,” says Rajeev.

Partnerships
The chickpea work is led by the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), working with partners at the Ethiopian Institute of Agricultural Research, Egerton University in Kenya, and the Indian Agricultural Research Institute. Additional collaborators in Phase I included the University of California–Davis (USA), the National Center for Genome Resources (USA) and DArT P/L (Australia).

For more information on the overall work in chickpeas, please contact Rajeev K Varshney, Principal Investigator of the chickpea work.

Video: Featuring Rajeev and partners Fikre Asnake (Ethiopia) and Paul Kimurto (Kenya)

Related links