Sep 012014
 

Scouring the planet for breeding solutions

Bindiganavile Vivek

Bindiganavile Vivek

Bindiganavile Vivek (pictured) is a maize breeder working at the International Maize and Wheat Improvement Center (CIMMYT), based in Hyderabad, India. For the past five years, Vivek and his team have been developing drought-tolerant germplasm for Asia using relatively new molecular-breeding approaches – marker-assisted recurrent selection (MARS), applied in a genomewide selection (GWS) mode. Their work in the Asian Maize Drought-Tolerance (AMDROUT) project is implemented through GCP’s Maize Research Initiative, with Vivek as the AMDROUT Principal Investigator.

Driven by consumer demand for drought-tolerant maize varieties in Asia, the AMDROUT research team has focussed on finding suitable drought-tolerant donors from Africa and Mexico. Most of these donors are white-seeded, yet in Asia, market and consumer preferences predominantly favour yellow-seeded maize. Moreover, maize varieties are very site-specific and this poses yet another challenge. Clearly, breeding is needed for any new target environments, all the while also with an eye on pronounced market and consumer preferences.

(1) Amazing maize and its maze of colour. Maize comes in many colours, hues and shapes. (2) Steeped in saffron: from this marvellous maize mix and mosaic, the Asian market favours yellow maize.

(1) Amazing maize and its maze of colour. Maize comes in many colours and hues. (2) Steeped in saffron: from this marvellous maize mix and mosaic, the flavour in Asia favours yellow maize.

Stalked by drought, tough to catch, but still the next big thing

Around 80 per cent of the 19 million hectares of maize in South and Southeast Asia is grown under rainfed conditions, and is therefore susceptible to drought, when rains fail. Tackling drought can therefore provide excellent returns to rainfed maize research and development investments. As we shall see later, Vivek and his team have already made significant progress in developing drought-tolerant maize.

Drough in Asia_Vivek slide_GRM 2013_w

The stark reality of drought is illustrated in this warning sign on a desiccated drought-scorched landscape, showing the severity of drought in Asia

But they are after a tough target: drought tolerance is dodgy since it is a highly polygenic trait, making it difficult for plant scientists to pinpoint genes for the trait (see this video with an example from rice in Africa). In other words, to make a plant drought-tolerant, many genes have to be incorporated into a new variety. As one would expect, the degree of difficulty is directly proportional to the number of genes involved. In the private-sector seed industry, MARS  (PDF) has been successfully used in achieving rapid progress towards high grain yield under optimal growth conditions. Therefore, a similar approach could be used to speed up the process of introducing drought tolerance into Asian crops – the reason why the technique is now being used by this project.

AMDROUT Meeting Penang Dec2010_w

More than India: the AMDROUT project also comprises research teams in China, Indonesia, Thailand, The Philippines and Vietnam. In this photo taken during the December 2010 annual project meeting in Penang, Malaysia, the AMDROUT team assessed the progress made by each country team, and  team members were trained in data management and drought phenotyping. They also realised that there was a need for more training in genomic selection, and did something about it, as we shall see in the next photo. Pictured here, left to right: Luo Liming, Tan jing Li, Villamor Ladia, V Vengadessan, Muhammad Adnan, Le Quy Kha, Pichet Grudloyma, Vivek, IS Singh, Dan Jeffers (back), Eureka Ocampo (front), Amara Traisiri and Van Vuong.

The rise of maize: clear chicken-and-egg sequence…

Vivek says that the area used for growing maize in India has expanded rapidly in recent years. In some areas, maize is in fact displacing sorghum and rice. And the maize juggernaut rolls beyond India to South and Southeast Asia. In Vietnam, for example, the government is actively promoting the expansion of  maize acreage, again displacing rice. Other countries involved in the push for maize include China, Indonesia and The Philippines.

So what’s driving this shift in cropping to modern drought-tolerant maize? The curious answer to this question lies in food-chain dynamics. According to Vivek, the dramatic increase in demand for meat – particularly poultry – is the driver, with 70 percent of maize produced going to animal feed, and 70 percent of that going into the poultry sector alone.

GCP gave us a good start… the AMDROUT project laid the foundation for other CIMMYT projects”

 Show and tell: posting and sharing dividends

As GCP approaches its sunset in December 2014, Vivek reports that all the AMDROUT milestones have been achieved. Good progress has been made in developing early-generation yellow drought-tolerant inbred lines. The use of MARS by the team – something of a first in the public sector – has proved to be useful. In addition, regional scientists have benefitted from broad training from experts on breeding trial evaluation and genomic selection (photo-story on continuous capacity-building). “GCP gave us a good start. We now need to expand and build on this,” says Vivek.

AMDROUT trainees at Cambridge_w

AMDROUT calls in on Cambridge for capacity building. AMDROUT country partners were at Cambridge University, UK, in March 2013, for training in quantitative genetics, genomic selection and association mapping. This was a second training session for the team, the first having been September 2012 in India.
Pictured here, left to right – front row: Sri Sunarti, Neni Iriany, Hongmei Chen;
middle row: Ian Mackay (Cambridge), Muhammad Azrai, Le Quy Kha, Artemio Salazar;
back row: Roy Efendy, Alison Bentley (who helped organise, run and teach on the course, alongside Ian) and Suriphat Thaitad.AMDROUT country partners are from China’s Yunnan Academy of Agricultural Sciences (YAAS); the Indonesian Cereals Research Institute (ICERI); the Institute of Plant Breeding at the Unversity of Philppines at Los Baños (UPLB); Thailand’s Nakhon Sawan Field Crops Research Center (NSFCRC); Vietnam’s National Maize Research Institute (NMRI); and private-sector seed companies in India, such as Krishidhan Seeds.Curious on who proposed to whom for this AMDROUT–Cambridge get-together? We have the answer: a Cambridge callout announced the training, and AMDROUT answered by calling in, since course topics were directly relevant to AMDROUT’s research approach. 

 

 

According to Vivek, the AMDROUT project laid the foundation for other CIMMYT projects  such as the Affordable, Accessible, Asian (AAA) Drought-Tolerant Maize (popularly known as the ‘Triple-A project’) funded by the Syngenta Foundation for Sustainable Agriculture. This Triple-A project is building on the success of AMDROUT, developing yet more germplasm for drought tolerance, and going further down the road to develop hybrids.

 

Outputs from the AMDROUT project will be further refined, tested and deployed through other projects”

Increasing connections, and further into the future

Partly through GCP’s Integrated Breeding Platform (IBP), another area of success has been in informatics. Several systems such as the Integrated Breeding FieldBook, the database Maize Finder and the International Maize Information System (IMIS) now complement each other, and allow for an integrated data system.

There is now also an International Maize Consortium for Asia (IMIC–Asia), coordinated by CIMMYT, comprising a group of 30 commercial companies (ranging from small to large; local to transnational). Through this consortium, CIMMYT is developing maize hybrids for specific environmental conditions, including drought. IMIC–Asia will channel and deploy the germplasms produced by AMDROUT and other projects, with a view to assuring impact in farmers’ fields.

Overall, Vivek’s experience with GCP has been very positive, with the funding allowing him to focus on the agreed milestones, but with adaptations along the way when need arose: Vivek says that GCP was open and flexible regarding necessary mid-course corrections that the team needed to make in their research.

But what next with GCP coming to a close? Outputs from the AMDROUT project will be further refined, tested and deployed through other projects such as Triple A, thus assuring product  sustainability and delivery after GCP winds up.

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As our Maize Research Initiative does not have a Product Delivery Coordinator, Vivek graciously stepped in to coordinate the maize research group at our General Research Meeting in 2013, for which we thank him yet again. Below are slides summing up the products from this research, and the status of the projects then.

Jan 282013
 

Today, Nature Biotechnology published the first-ever draft genome sequence map for a chickpea variety (PDF). The map will help researchers and breeders the world over to – through molecular breeding methods – deliver to growers higher-yielding more resilient varieties of chickpeas. 

Now that we have the rewards in a nutshell, and we choose to chew the chestnut of challenges later in the story, let’s next decipher the ‘Rajeevs’ part in the title: introducing Rajeev K Varshney, our very own Leader of Comparative and Applied Genomics, who also led and coordinated the transnational collaboration that developed this map.

We had the pleasure of talking to the gently-spoken Indian, a week before the release of the paper, asking him to recount how the project began, and the challenges and success they faced along the way. We’ll soon get to what Rajeev had to say, but first, a rapid rewind for backgrounding before Rajeev tells us the rest of the story…

… we have the ‘borders’ done… a good idea of what the picture is, and where the rest of the pieces will fit.”

Rajeev in the lab.

Reality check from the Genomics Gnome of Good News: two is but the twinkling of an eye…
The sequence map of the genotype CDC Frontier – a Canadian kabuli chickpea variety – took about two years to construct.”

No, the time taken is not the challenge since we’re yet to get to that part. In fact, in the world of genomics , two years is fairly fast, compared to, say, the time taken for sequencing other grain genomes such as maize, rice and wheat.

Rajeev attributes this to the interdisciplinary expertise of his team, most of whom are world leaders in their field, and to the enthusiasm and generosity of all partner institutes who funded the collaboration.

And with that background, on to our chat with Rajeev!

Sandwiches in the Sunshine State, and a search starts for the then unattainable holy grail

Q: Is it correct that this project started over sandwiches under a sunny sky in California?
Funnily enough, yes. We had the preliminary discussion during a lunchtime break at the fifth International Congress on Legume Genetics and Genomics back in July 2010. Doug Cook, from the University of California, Davis, and I, organised the meeting for select attendees to discuss the idea.

With daughter, Nanz. Rajeev in ‘Daddy-mode’, a galaxy away from genomic research.

Many researchers at the time had, or were toying with, sequencing parts of the chickpea genome to discover genes that helped plants tolerate salinity, drought, disease, and so on. The idea of mapping the whole genome, however, was thought to be unachievable given the cost and resources required. What Doug and I proposed to the 10-odd senior researchers that day was that we form an alliance to pool together our knowledge, funds and resources.

When we returned to our home institutes, we all approached our institutes or funding agencies in respective countries, to propose they consider funding the collaborative project. To be honest, this was probably the most challenging task of the project, as it often is with other projects, as they had a hard time recognising the benefits. However, we finally got there, and with the help of more than 20 institutes from North and Central America, Asia, Australia and Europe, we have successfully assembled 74 percent of the genome within two years.

Pieces fall into place for mix-and-match combinations

Now, you may say that 74 percent doesn’t equal the whole genome, but it does provide us with a map and pointers we’d never had before. Imagine doing a jigsaw without a picture to guide you – that’s how hard it was for us at the start. Now at least we have the ‘borders’ done, and we have a good idea of what the picture is, and where the rest of the pieces will fit.

Q:Why is mapping the chickpea genome so important?
Having the genome mapped is going to benefit all chickpea breeders, researchers and growers.

Say a conventional breeder wanted to create a new breed of chickpeas with drought tolerance. They would cross a domesticated, high-yielding variety of chickpeas, with a variety that tolerates dry conditions – most likely, lower-yielding – and then grow the progeny in the field. They wait for these progenies to grow, then visually select the best lines and make crosses with these. They keep doing this process over and over again for six to seven years until they’ve generated a new variety with the desired trait.

Different breed, mould and mode

Molecular breeders do it differently: instead of selecting the lines by visual inspection, they select lines based on their genes. This means they can correctly trace whether the progeny has received the genes which help the plant tolerate drought and only grow, test and cross with these plants, almost halving the time it would take through conventional methods.

With the map, researchers will be able to more rapidly identify genes of interest, and work with breeders to select for plants that display the favourable traits of these genes, whether this be for drought tolerance, pest resistance or for any other trait they are interested in.

Q: Good for researchers and breeders, but how is that going to benefit growers though?
Knowing which plant is more tolerant of drought from the start of the breeding process is going to significantly reduce the time it takes for breeders to develop these types of chickpea cultivars. So, growers will have new breeds of higher-yielding more resilient chickpeas available sooner.

Ethiopian farmer, Temegnush, and her chickpea harvest.

Remember also that chickpeas are a very important crop for smallholders in the resource-poor harsh environments of sub-Saharan Africa, India and Southeast Asia. Not only do they grow it for food and to replenish soil nitrogen, they also export to India, the world’s largest consumer of chickpeas. Most of these farmers would be lucky to harvest one tonne per hectare, so any yield advantage means extra income.

This point is particularly relevant for GCP’s goal, which is to improve the livelihoods of such farmers.

Q: This was one of the largest collaborative projects you’ve coordinated in your relatively short career. What was the most challenging aspect?
Short answer is….many!  With it being a collaborative project, bringing together researchers from all around the world, it was always difficult to coordinate suitable times for Skype and phone meetings.

Personally though, my biggest challenge was trying to coordinate so many esteemed researchers. We all had great ideas and we all thought each of our ideas was the right one. I had to resolve all issues amicably and find a solution to move forward.

Luckily I have surrounded myself over the years with some good colleagues to whom I’ve always been able to turn to discuss any problems. Jean-Marcel Ribaut, who is the Director of GCP, was one particular colleague to whom I often turned to for advice, given his experience with coordinating all of GCP’s collaborative interdisciplinary projects. He also helped source much-needed funds and suggested several useful partnerships, which were vital in carrying out the project.

My boss at ICRISAT, William Dar, the Director General, has always been very supportive, and time and again went out of his way to make sure I had the funds, capacity and sanity to keep the project going! I am deeply indebted to him.

The future

Q: How will the research continue?
Researchers and breeders will be able to customise the genome map to fit their particular purposes. Most will be interested in using it to develop molecular markers, which breeders can use to highlight specific genes of interest for molecular breeding. As I mentioned earlier, this could realistically halve the time it takes to breed new varieties from six to10 years to four to five years.

One outcome of the project, which I’m particularly interested in exploring further, relates to chickpea diversity. When we compared the 90 chickpea genomes, we realised that that diversity in the elite varieties was very low, meaning they all had very similar alleles (form of genes).

This has come about because over the years, breeders and growers have continually chosen only a handful of chickpea varieties to continually breed with. This is because these breeds tend to produce higher yields, something which all growers want.

The drawback of this, however, is that if all the popular breeds are too similar, then they could all be susceptible to a particular disease. If this particular disease were to strike, then chickpeas could be wiped out – globally.

So this map will be a valuable tool to use to enhance genetic diversity in the elite gene pool, thus safeguarding the world’s supply of chickpeas.

 

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