Mar 042014
‘Made (up) in Ghana’

In the world of crop research as in the fashion industry, there are super-models, mere models, spectators and rank outsiders. Make no bones about it, trusty old cassava (Manihot esculenta) is a crop of very modest beginnings, but now finally strutting the research catwalk alongside the biggest and the best.

Elizabeth Parkes

Elizabeth Parkes

An ancient crop thought to have been first domesticated in Latin America more than 10,000 years ago, it was exported by Portuguese slave traders from Brazil to Africa in the 16th century as a cheap source of carbohydrates. From there, today we travel half a millennium forward in time – and in space, on to Ghana – to catch up with the latest on cassava in the 21st century.

Come on a guided tour with Elizabeth Parkes (pictured), of Ghana’s Crops Research Institute (CRI, of the Council for Scientific and Industrial Research, CSIR), currently on leave of absence at the International Institute of Tropical Agriculture (IITA).

A hard-knock life, but still going strong
In keeping with its humble heritage, cassava is a crop which has long been reputed for being more than a little worn through at the elbows, commonly known as a “poor man’s crop” according to GCP cassava breeder and researcher, Elizabeth Parkes. However, much like a dishevelled duffle coat, what the crop lacks in shimmer and shine, it makes up for in sturdiness and dependability, rising to the occasion time and again by filling a critical gap – that of putting food in bellies – with a readiness and ease that its more sophisticated crop relatives have often struggled to keep up with. Elizabeth explains:  “It has kept people alive over the years.” By the same token, the crop – now one of Africa’s most important staples – is fondly known in Ghana as bankye, meaning a ‘gift from the government’, thanks to its reliability and capacity to meet needs that other crops cannot. There is even a popular song in the country which pays homage to the crop as an indefatigable evergreen, conquering even the most willful and wily of weeds!

However, as cassava experts such as Elizabeth know only too well, behind this well-intentioned lyrical window dressing is the poignant story of a crop badly in need of a pressing pick-me-up. Hardy as it may seem on the surface, cassava is riddled with myriad problems of a political, physiological, environmental and socioeconomic nature, further compounded by the interactions between these. For starters, while it may be a timeless classic and a must-have item at the family table for a good part of Africa, à la mode it is not, or at least not for short-sighted policy-makers looking first and foremost to tighten their purse strings in straitened times, or for quick-fix, rapid-impact,  silver-bullet solutions: “African governments don’t invest many resources in research. Money is so meager, and funds have mostly come from external agencies looking to develop major cereals such as rice. Cassava has been ignored and has suffered a handicap as a result – it’s more or less an orphan crop now,” Elizabeth laments. Besides having to bear witness to their favourite outfit being left on the funding shelf, cassava breeders such as Elizabeth are also faced with a hotchpotch of hurdles in the field: “In addition to factors such as pests and disease, cassava is a long-season and very labour-intensive crop. It can take a whole year before you can expect to reap any rewards, and if you don’t have a strong team who can step in at different points throughout the breeding  process, you can often find unexpected results at the end of it, and then you have to start all over again,” Elizabeth reveals. Robust as it may be, then, cassava is no easy customer in the field: “After making crosses, you don’t have many seeds to move you to the next level, simply because with cassava, you just don’t get the numbers: some are not compatible, some are not flowering; it’s a real bottleneck that needs to be overcome,” she affirms.

No time for skirting the issue
And at the ready to flex their research muscles and rise to these considerable challenges was Elizabeth and her Ghanaian CRI  team, who – with GCP support and in unison with colleagues from across Africa and the wider GCP cassava community – have been working flat out to put cassava firmly back on the research runway.

Thanks to funders such as GCP, who recognised that we couldn’t afford to turn a blind eye to the plight of this struggling crop, cassava has been given a voice…cassava is no longer just a poor man’s staple” 

A cassava farmer in Northern Ghana.

A  cassava farmer in Northern Ghana.

Elizabeth walks us through the team’s game plan: “GCP socioeconomist Glenn Hyman and team undertook a study to identify the best area in Ghana for supporting cassava flowering [Editor’s note: Glenn works at the International Center for Tropical Agriculture, CIAT]. Armed with that information, we have been applying grafting techniques, using hormones to induce flowering in Ghana and beyond.” The initiative is starting to bear fruit: “At the IITA–Nigeria Ubiaja site, for example, flowering is underway at factory-like efficiency – it’s a great asset. The soil has also greatly improved – we haven’t been able to pinpoint the exact cause yet, but what we’ve seen is that all cultivars there will now flower,” she reveals. Elizabeth’s team has been making steady progress in biotechnological techniques such as DNA extraction: thanks to work led by then GCP cassava comrade Martin Fregene (then with the International Center for Tropical Agriculture, CIAT, and now with the Donald Danforth Plant Science Center) and colleagues, focusing on the development of more reliable and robust simple sequence repeat (SSR) markers, Elizabeth was able to carry out genetic diversity diagnosis work on cassava, collecting germplasm from all over Ghana for the global GCP cassava reference set. [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]

Similar work was also conducted in Nigeria and Guatemala. So has this tremendous and tenacious teamwork proved strong enough to drag cassava out of the doldrums? Elizabeth certainly seems to think so: “Thanks to funders such as GCP, who recognised that we couldn’t afford to turn a blind eye to the plight of this struggling crop, cassava has been given a voice. Having worked together to understand the peculiarities of this crop, cassava is no longer just a poor man’s staple: beyond subsistence, it is becoming a crop of high starch quality, and of real use for industry, confectionary and even biofuels,” she enthuses.

Thankfully, it’s a most welcome change of tide that shows no sign of abating any time soon.  Human capacity, Elizabeth says, is going from strength to strength, with three GCP-funded Ghanaian postgraduate students advancing well, two of them working on PhDs in what would normally be considered, according to Elizabeth, a ‘no-go area’ of cassava research – that is, cassava drought tolerance and post-harvest physiological deterioration (PPD), as well as bio-fortification. Efforts by the CRI team have resulted in the release of some 14–15 new drought-tolerant and PPD-resistant varieties in Ghana to date; all are anticipated to have a long shelf-life, and other varieties are also in the pipeline. Biofortified seeds are in the making, with a view to soon mainstream biofortification in the team’s breeding activities. The biofortification work is in collaboration with a sister CGIAR Challenge Programme, HarvestPlus.

The impact of our GCP-supported research on cassava has been remarkable. Above all, it’s been the community spirit which has moved things forward so effectively; in this respect, I think researchers working on other crops might want to borrow a leaf from the cassava book!”

Molecular masterstrokes, a leaf to lend despite cold shoulder, and a ‘challenge crop’ befitting Challenge Programmes
Forthcoming plans for Elizabeth and her cassava companions in Ghana include a GCP Cassava Challenge Initiative project which will seek to unearth new marker populations and materials which are drought-tolerant and resistant to cassava mosaic virus and cassava bacterial blight. The team has successfully introgressed materials from CIAT into their landraces, and the next step will be to gauge how best the new genes will react to these traits of interest. In terms of people power, the CRI biotechnology laboratory built with GCP support – and now a regionally accredited ‘Centre of Excellence’ – is a hive of activity for local and international scientists alike, and is consequently bolstering cassava research efforts in the wider subregion. “The impact of our GCP-supported research on cassava has been remarkable. Above all, it’s been the community spirit which has moved things forward so effectively; in this respect, I think researchers working on other crops might want to borrow a leaf from the cassava book!” Elizabeth ventures.

Reflecting back on the conspicuous cocktail of constraints which mired the crop in the early days of her research career – challenges which often resulted in a cold shoulder from many of her research peers over the years – Elizabeth recalls affectionately: “At first, people didn’t want to work on cassava since it’s truly a challenge crop: the genetics of cassava are really tricky. Colleagues from around the globe often asked me: ‘Why not go for a smooth crop which is friendly and easy?’” Her commitment, however, has been unfaltering throughout: “I’ve stuck with cassava because that’s my destiny! And now I see SNPs being developed, as well as numerous other resources. Once you clean something up it becomes more attractive, and my thanks go out to all those who’ve remained dedicated and helped us to achieve this.”

Thus, dusted down and  ‘marked-up’ with a molecular make-over well underway, all evidence now suggests that this once old-hat subsistence crop is en route to becoming the next season’s big research hit, with shiny new cassava varieties soon to be released at a field station near you! Go, Ghana, go!



Nov 132012

Bean breeding in his bones: Asrat A Amele

For our bean team, we already see the benefits of being in the Tropical Legumes I  project. We now understand molecular breeding, and we are able to apply molecular breeding techniques.” – Asrat A Amele (pictured)

Asrat is a bean breeder at Ethiopia’s South Agricultural Research Institute (SARI) at the Awassa Research Centre.

Besides breeding beans that will better battle drought, Asrat’s team combines drought tolerance with resistance to the bean stem maggot (BSM) – a pest that afflicts all bean-growing zones in Ethiopia.

Connections, continuity and capacity building
The Tropical Legumes I (TLI) was not an entirely new connection, as Asrat’s involvement with GCP predates this particular project. He started off as a GCP-funded fellow in 2007, investigating bean genetics for drought tolerance. The fellowship would also seem him do a stint in Colombia at the International Center for Tropical Agriculture  (CIAT, by its Spanish acronym). His work at the time on root phenotyping and quantitative trait loci (QTL) analysis has since been published.

At that time, Asrat remarked:

The GCP fellowships programme is great for a person like me, working in a developing-country research institute. I can say it potentially provides researchers with up-to-date scientific knowledge in areas of specialisation. It provides better contact with scientists in other parts of the world and opens a wider window to think on problems and deliver better research products.”

Thorugh GCP, Asrat also attended a molecular breeding course at Wageningen University and Research Centre in The Netherlands. Wageningen is a GCP Consortium member.

The ravages wrought by bean stem maggot.

Having passed through that door of opportunity and looking back now, what does Asrat say? “Through TLI, we were able to access new parental sources of germplasm recommended for release and use for breeding. For instance, we’ve received more than 200 lines from CIAT, from which 10 have been selected to be used as parents. We plan to do crosses with these parents to develop a marker-assisted recurrent selection [MARS] population, based on the problems plaguing beans in Africa.”

And it’s not all about material but also matters cerebral (and matters manual, as we shall see further on): “From the science meetings we attend, we’ve also gained valuable new contacts and acquired new knowledge.” Asrat reveals.

Two…and two

Fitsum Alemayehu

Daniel Ambachew

The next step is to validate the workability of MARS, and SARI has a GCP-funded PhD student, Fistum Alemayehu (pictured right), registered at the South Africa’s Free State University and conducting his phenotyping in Ethiopia, alongside other well-trained staff that SARI now has. Fistum is working on marker-assisted recurrent selection for drought tolerance in beans, while Daniel Ambachew (pictured left), another GCP-funded MSc student enrolled at Haramaya University, Ethiopia, is evaluating recombinant inbred line populations and varieties for combined dual tolerance of drought and bean stem maggot.

Both students are using molecular breeding: “For this work, we’ll be using SNP* markers. It is probably the first use of bean SNPs in sub-Saharan Africa. We will now do QTL analysis with the bean population we have from CIAT,” reveals Asrat.

* SNP: (pronounced ‘snips’) is a technical term, and the abbreviation is derived from ‘single nucleotide polymorphism’ – an advanced molecular-marker system widely used in genetic science. You can read more about SNPs in this press release.

Of humans and machines

A training session on maintaining farm machinery.

Moving on to matters manual and mechanical, besides enhanced human resources, SARI has benefited from infrastructure support as part of GCP’s comprehensive capacity-building package: the Institute now has an irrigation system to enable them conduct drought trials, and SARI technicians from more than 20 different SARI stations have been trained in proper use and routine maintenance of farm machinery. SARI also received two automatic weather stations from GCP for high-precision climatic data capture, with automated data loading and sharing with other partners in the network.

Through this project, SARI is now well tuned into the international arena of bean research and development, and profiting in new ways from this exposure to growing international connections.

Water drilling to install irrigation equipment at SARI.

Institutional revolution and rebirth
The engagement with GCP has revolutionised bean breeding at SARI and institutionalised marker-assisted selection. As a result, SARI will soon have a small molecular breeding laboratory funded by another agency. This lab will support one more PhD student and an additional MSc student, both registered in Ethiopian universities and working on marker-assisted selection for beans.

Thus, in this southern corner of Ethiopia, bean breeders conversant in molecular methods will continue to be ‘born’, better-prepared and well-equipped to meet the challenges facing bean breeding today.




Asrat on video


SLIDES: Phenotyping common beans for tolerance of drought and bean stem maggots in Ethiopia


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.

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)

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