- International breeding programs are now fast-tracking the introduction of innovative cereal germplasm into Australian trials
- These trials offer the only direct comparison between lines from the two main global cereal and pulse breeding centres, CIMMYT and ICARDA
- The subsequent data and the seed resulting from this testing is crucial to the continuing development of Australian wheat, durum, barley and chickpea industries
Space was limited, but the dialogue free-flowing, on the minibus that carried a group of the world’s leading plant breeders to internationally significant field trials across Australia.
The CAIGE tour team 2015 hits the road: (from left) Dr Karim Ammar (Borlaug Global Rust Initiative), Dr Amer Dababat (CIMMYT), Dr Wuletaw Tadesse (ICARDA), Dr Suchismita Mondal (CIMMYT), Dr Hans Braun (Consortium Research Program on Wheat) and Professor Richard Trethowan (Plant Breeding Institute).
PHOTO: Gio Braidotti
Just as Australian wheat crops were flowering in 2015, a group of researchers representing a global cereal breeding alliance took to the road in a minibus to undertake a rather unusual sightseeing trip for would-be tourists.
Despite the lure of a giant red rock, prawns and coral reef, it was crop germplasm that these visitors had come to see.
At Narrabri, North Star and Junee in New South Wales, then Horsham in Victoria, Roseworthy in South Australia, and Toodyay and Mukinbudin in Western Australia, the stop-over attractions were the same: field trials.
Dr Ravi Singh, head of wheat improvement and rust research at CIMMYT, with his China Friendship Award.
PHOTO: Clyde Beaver, CIMMYT
The International Maize and Wheat Improvement Center (CIMMYT) chief wheat breeder, Dr Ravi Singh, has often participated in the CAIGE tour, but in 2015 was waylaid by the Government of China. In Beijing on 7 October, Dr Singh received the Friendship Award – China’s highest honour to foreign experts who have contributed to the country’s economic and social progress.
Dr Singh’s aid to China’s agricultural development spans 30 years and includes sharing improved germplasm, knowledge about rust-disease-resistance genetics and scientific training.
“During that time, China increased wheat production while reducing the amount of land sown to wheat by about 20 per cent,” Dr Singh said at the award ceremony. “It’s a remarkable success story, enhancing food productivity and the income of millions of women and men; small-scale growers who embraced innovations and responded to the responsibility of enhancing food production.”
The award is a reminder that despite CIMMYT’s impressive benefits to Australia – where about 95 per cent of wheat varieties have CIMMYT parents – the centre, along with the other 14 centres in the Consultative Group for International Agricultural Research Consortium, was established to alleviate global poverty.
Within the neatly replicated plots at each site was a selection of elite wheat lines bred from the world’s most environmentally adaptable gene pool at the International Maize and Wheat Improvement Center (CIMMYT), and the genetic resource embodying the most tolerant to hot and dry conditions from the International Center for Agricultural Research in the Dry Areas (ICARDA).
The wheat lines amount to the world’s best attempt to secure wheat production against the most extreme challenges facing growers – from increasing extremes of climate variability through to the outbreak of new, potentially devastating rust variants.
The presence of this germplasm in Australia is made possible by a GRDC-mediated agreement that fast-tracks the innovative breeding material developed internationally into Australian field trials through the CIMMYT Australia ICARDA Germplasm Evaluation (CAIGE) program.
At the wheel of both the CAIGE program – and the minibus – was Professor Richard Trethowan, a former CIMMYT wheat breeder who is now director of the IA Watson Grains Research Centre at the Narrabri node of the University of Sydney’s Plant Breeding Institute.
Professor Trethowan explained that CAIGE is not limited to bread wheat but over the program’s decade-long life span has expanded to include durum wheat, barley and chickpeas.
Negotiations are underway to also include chickpea breeders and the germplasm available at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) in India, as the program’s practical value to both the international centres and to the Australian grains industry continues to push its expansion.
“CIMMYT, ICARDA and ICRISAT have collected so much of the world’s existing biodiversity in their genebanks and they have the capacity to exploit that diversity through their breeding strategies and facilities,” Professor Trethowan said. “Their germplasm is amazingly valuable and with CAIGE, we have created a system to maximise its use in Australia.”
The CAIGE project
Every year CIMMYT and ICARDA breeders each select a subset of about 100 wheat lines best suited to Australia from their international nurseries. Australian breeders also visit these centres, alternating between CIMMYT and ICARDA each year. There, they get to choose additional material to include in the CAIGE package.
The seed is fast-tracked to Australia and spends the first year on its arrival in quarantine before it is extensively tested for disease resistance and bulked up for sowing in the following year at seven locations across Australia.
While the lines have already undergone field trials across the world, only in Australia, through CAIGE, is it possible to directly compare CIMMYT and ICARDA varieties head to head within the same trial.
Making direct comparisons possible, both between trial sites and across data collected in different years, is the inclusion of a standard set of elite Australian varieties – such as Gladius, Mace and Suntop – side by side with the check varieties routinely used by CIMMYT and ICARDA in their own field trials.
The outcome is an extensive dataset, freely available through the CAIGE website that is administered by Sandra Micallef. The data sets up comprehensive analysis capabilities for all the world’s major wheat-growing areas.
It functions like a high-resolution lens that can reveal a line’s yield potential, stability and adaptability to all major environment types, along with climate and disease stresses.
The data also reveal correlations between environments scattered across the world. Wheat suited to Narrabri, for example, does well in South Asia and China and these correlations help focus the search for suitable diversity to introduce into Australian cultivars.
Since its inception, the CAIGE trials have been of great interest to Australian breeding companies and part of the CAIGE agreement provides Australian breeders with equal access to the material and data.
In exchange, breeding companies such as Australian Grain Technologies (AGT), InterGrain, LongReach Plant Breeders, Edstar Genetics and Bayer CropScience manage individual trial sites as an in-kind service and share all the resulting data (Table 1). They are then at liberty to use CAIGE material in their own commercial breeding programs, without having to share data on derived lines.
“The latest AGT variety, SuntopA, for example, resulted from a cross with a CIMMYT parent that came through the CAIGE program,” Professor Trethowan said.
“The only reason the elite international material is not released as varieties here is because they lack the quality traits demanded by the buyers of Australian wheat.”
Australian pre-breeders also access the material, using it in their trait discovery, genomic and marker development research.
“With CAIGE, the end goal is all about enhancing yield and yield stability both for growers in Australia and globally.”
Table 1 Australian wheat breeding companies participate in CAIGE by running most of the field trials located at seven sites across three growing regions.
||Field trial management
||University of Sydney
||Australian Grain Technologies (AGT)
||LongReach Plant Breeders
||Australian Grain Technologies (AGT)
Professor Richard Trethowan, firstname.lastname@example.org
Dr Hans Braun – managing the legacy of 140 wheat breeding cycles.
PHOTO: Gio Braidotti
On the road with Dr Hans Braun
It is the breeding philosophy of the International Maize and Wheat Improvement Center (CIMMYT) that Dr Hans Braun – the man who essentially heads international wheat-breeding efforts – wanted to talk about en route to Horsham on the Victorian leg of the CAIGE tour.
It is a philosophy that has defied convention and exceeded expectations during the 75 years of its implementation.
“During 140 breeding cycles, CIMMYT has continually crossed the best material identified at different locations, accumulating the biodiversity that allows our wheat to cope well with climate variability,” Dr Braun said. “At CIMMYT, we believe this adaptability is important to achieving yield stability.”
Wheat is one of the few crops bred in this way. CAIGE scientists often encounter and value the resulting adaptability in their field trials.
“There was in the past a lot of discussion on breeding wheat with specific adaptation to a narrow geographic region,” he said.
“But at CIMMYT we felt there is too much variability in growers’ fields, especially relating to heat that is an important driver of yield, even if irrigation is available.
“And climatic variation (in temperature and rainfall) at one location over years can be as large or larger than climatic variation in one year over a huge geographic region. So we focus on producing what wheat growers in the developing world need – lines that can cope with climate variation.”
About 70 per cent of the spring wheat varieties grown in developing countries are CIMMYT-derived and to Dr Braun this fact represents a huge responsibility to continue providing growers with the best wheat lines possible.
However, just like Australian wheat breeders, CIMMYT wheat scientists constantly evaluate new breeding technologies to increase breeding efficiency.
“Before new breeding technologies are adopted, the material produced by these technologies needs to be tested in three years of trials in our international nursery system and demonstrate there is no negative impact on performance.”
Such a validation process is underway for genomic selection in a project run with Kansas State University, Cornell University and partners in India, Bangladesh and Pakistan. That project basically includes the entire CIMMYT spring wheat program and is funded by USAID and the Bill and Melinda Gates Foundation.
“What we do know about genomic breeding is that it cannot predict how the genes it selects will interact and how those interactions affect crop performance overall,” Dr Braun said.
“Given the number of genes under selection and the amount of variation possible at each gene, the overall number of possible interaction is huge. That’s why we still need multi-location field trials and I don’t see that changing for the foreseeable future.”
The CAIGE tour
Dr Suchismita Mondal (CIMMYT) and Dr Wuletaw Tadesse (ICARDA) at a coffee stop during the 2015 CAIGE tour, heading to Horsham, Victoria.
PHOTO: Gio Braidotti
Joining Professor Richard Trethowan on the 2015 CAIGE tour were two international wheat breeders – Dr Suchismita Mondal from the International Maize and Wheat Improvement Center (CIMMYT), who has a special interest in drought and heat-tolerance physiology and breeding, and Dr Wuletaw Tadesse from the International Center for Agricultural Research in the Dry Areas (ICARDA) Biodiversity and Integrated Gene Management Program. They were accompanied by CIMMYT plant pathologist and nematologist Dr Amer Dababat.
Also present was CIMMYT durum wheat breeder Dr Karim Ammar. Dr Ammar said that the first batch of CIMMYT durum lines imported under CAIGE arrived in 2015 and were extensively challenged with local disease strains – including crown rot at the University of Sydney – and bulked-up in preparation for sowing in 2016.
“My presence is more about seeing the trial sites and understanding the Australian growing environments,” Dr Ammar said. “I think it is important that the CIMMYT scientists come here to ‘calibrate their eyes’ so we can select material for CAIGE in a way that is relevant to Australian growers.”
ICARDA breeder Dr Tadesse agreed: “The first time ICARDA bread wheat was sown in CAIGE trials we could see we needed to change the way we select material for Australia. Now it is working well across all the sites. The ICARDA varieties are competitive with Australian checks, sometimes even beating them.”
Dr Ammar described experiencing a similar re-evaluation: “Before visiting Australia I thought the focus should be 100 per cent on drought tolerance. On seeing the northern environment flourishing, I realised that I have to combine that with emphasis on yield potential under favourable conditions.”
Also on board the minibus was a special guest, Dr Hans Braun, director of CIMMYT’s Global Wheat Program and of the Consortium Research Program on Wheat.
Dr Braun explained that CIMMYT incorporates a unique breeding philosophy in its shuttle breeding system that involves worldwide field trials.
“We have divided the world into 12 mega-environments,” Dr Braun said. “Included are irrigated and high-altitude areas but also regions characterised by low rainfall, acid soils, drought and heat that are of relevance to Australia.
“CIMMYT classifies all its breeding material according to yield capacity in these mega-environments. They select about 500 of the most appropriate wheat lines to distribute globally to 150 recipients, with about 500,000 envelopes of seed sent out each year.”
However, in initiating the next round of crosses, breeders introduced an important twist.
“Rather than select for high performance at any one particular location and environment, CIMMYT combines the best performing lines from all regions, ” Dr Braun said.
By continually crossing the best material from different locations, CIMMYT wheat varieties can now cope with a lot of agro-climatic variation at any one location.
“That adaptability is important for achieving yield stability and I think that is what makes this material so valuable,” Dr Braun said.
He said climate variability meant that unless a grower could be certain at sowing which variety would perform best, a variety that could cope with a range of challenges was needed.
This adaptability is clear at the CAIGE field trials. As Dr Mondal explained: “Each year we get some surprises; lines that have an in-built ability to adapt in ways that exceed our expectations.”
This takes the form of wheat lines that are in the top-performing group in all environments in the three growing regions, as was the case with Attila and, more recently, Borlaug 100.
At ICARDA, Dr Tadesse said the focus of the wheat breeding program was on preventing yield loss from drought, heat and diseases, such as rusts and septoria, given ICARDA’s focus on dry environments in the central Asia, west Asia and north Africa regions.
“We divide our germplasm into different groups that were bred to target different environments,” he said. “We use key location platforms in our breeding program: Morocco for drought, Sudan for heat, Egypt and Lebanon for yield potential, and Ethiopia for rusts.
“Using this approach, we develop widely adapted germplasm combining yield potential with resistance to the major biotic and abiotic stresses. So wherever we travel, there will be germplasm we expect to perform well.”
Dr Tadesse added that ICARDA is also the source of the barley and chickpea varieties that were included in CAIGE field trials for the first time in 2015 for barley and 2016 for chickpea. The CAIGE Barley Project runs its own separate field trials and is overseen by Dr Mark Dieters, from the University of Queensland.
Dr Tadesse stressed the importance of financial support from the GRDC. “We have a project underway to develop heat-tolerant germplasm, for example, that is supported by the GRDC,” Dr Tadesse said. “That support from Australia is extremely important.”
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GRDC Project Code
US00073, CIM00019, CIM00020