International work critical to Australia's wheat industry, says Dr Trethowan

Dr Trethowan grew up on a citrus and summer fruit orchard north of Sydney, and he envisaged becoming an orchardist or agriculturalist of some sort, but a passion for genetics at school prompted him to study agricultural science at the University of Sydney before completing a PhD in plant breeding.

However, Dr Trethowan "caught the bug" for international R&D after completing a post-doctoral wheat breeding fellowship at the International Maize and Wheat Improvement Centre (CIMMYT) in Mexico.

"I returned to Australia afterwards for personal reasons but never let go of the dream to contribute in some way," he said.

He became a wheat breeder with the University of Sydney based at Narrabri, then led the Victorian wheat breeding program.

But when he was asked to return to CIMMYT to lead the dryland breeding work, Dr Trethowan jumped at the opportunity.

"It was wonderful work and took me to most wheat-growing environments in the developing world," he said.

"It was great to see genetics making such a difference.

"Sometimes, it might just be resistance to a single disease that altered the whole farming system.

"Working across cultures and respecting how things work locally was a big part of the technology adoption process but was also incredibly rewarding."

Eventually, Dr Trethowan returned to Australia to take the chair of plant breeding at the University of Sydney.

"Since returning, I have kept and expanded these linkages and continue to explore avenues to bring about positive and sustainable change in key international farming systems through better genetics," he said.

When Dr Trethowan started as a wheat breeder, molecular technology was in its infancy, RFLPs were the big thing, and many people completely underestimated the time it would take to make these tools useful or practical.

Much has changed since then.

"Now, we use marker-assisted selection for known genes routinely, can sequence materials cheaply, integrate genomic selection in cultivar development and change the expression of genes using gene editing," Dr Trethowan said.

"The time to develop new cultivars has halved, and genetic advances significantly increased.

"How we use machine learning and other aspects of artificial intelligence to improve efficiency and accuracy is the next frontier."

Dr Trethowan's interest has always been in developing cultivars better adapted to abiotic stresses, mainly heat and drought.

This has been vital to maintaining yield potential so farmers worldwide could make the most of their income in better cropping years.

He and his team have experimented with new breeding techniques, including simulated field environments in Mexico for selection (with stress patterns generated that mimic major wheat growing environments globally), using marker-assisted recurrent selection for drought and related complex traits in India, China and Australia, implementing genomic selection for temperature tolerance in a nationally focussed pre-breeding effort to support our commercial wheat breeders and more recently, developing and using a genetic system for efficiently making wheat hybrids to provide wheat growers with the benefits of hybrid vigour.

"We have moved the later technology offshore and are working to introduce hybrid wheat into Pakistan, Bangladesh and Ethiopia," Dr Trethowan said.

"Of course, I need to shout out to the organisations that have and/or still support all this work, including the GRDC, ACIAR, Innovate UK, the Generation Challenge Program and the University of Sydney."

Another area of focus is on improving the nutritional value of wheat and wheat flour.

"We've targeted antinutritional factors that bind Zn and Fe in the human gut to try and improve nutritional value - we've taken this route because there is no yield penalty (unfortunately, increasing the concentration of Fe and Zn in the grain does have a yield penalty)," he said.

Dr Trethowan's research has resulted in 45 wheat cultivars being directly released to farmers across 13 countries.

Additionally, more than 150 wheat cultivars containing one or more parents from his research have been released globally, including genetic improvement for drought tolerance.

"My pre-breeding outputs (new lines with new traits) have been used, and continue to be used, as parents by commercial breeders to create new and better cultivars for growers - this is the end game for all we pre-breeders," he said.

"Collaboration is key to plant breeding, and our international linkages have been critical to accessing new genetic diversity to benefit our wheat industry.

"Our linkages with CIMMYT, the International Centre for Agriculture Research in the Dry Areas (ICARDA), India, Pakistan, Central Asia and South America have given our pre-breeding work new diversity that channels into commercial programs.

"For example, diversity for heat tolerance obtained under a bilateral agreement with India is an important component of heat resistance in new pre-breeding materials that even withstand the temperatures in the Kimberly (we validate the new genetics at Kununurra).

"Our new wheat hybrids are also being tested nationally in partnership, and we hope to see these commercially available soon.

"This is always a team effort - while I lead them, it is the multidisciplinary nature of the team that creates success."

Dr Trethowan now leads various national and international initiatives to improve crop productivity in stressed environments. In the GRDC-funded Germplasm Evaluation (CAIGE) program, he travels to Morocco or Mexico each year to identify new wheat lines for Australian conditions.

"Our CIMMYT Australia ICARDA Germplasm Evaluation (CAIGE) program, supported by GRDC, has forged strong links between Australia and these important international wheat breeding organisations," he said.

"Each year, I lead a team of Australian wheat breeders to the centres, alternating between Mexico and Morocco, to select germplasm ideally suited to our conditions."

Dr Trethowan said the glaring difference between farming systems in these countries and Australia is scale and mechanisation.

"Our farmers are quick to adopt the latest technology as labour is the most significant limitation - not so in Mexico and Morocco, where investment is lower and historical land tenure policies result in small holdings," he said.

"Nevertheless, some things are similar. Everyone wants high yield and yield stability..

"Quality is paramount here in Australia as our wheat market is segregated by class, whereas in most developing countries, wheat is often made into flat breads, and industrial quality is less of an issue.

"Nevertheless, nutritional quality is much more important overseas as Fe and Zn deficiencies are widespread in the developing world."

Dr Trethowan has always enjoyed the diversity of people, cultures and farming systems worldwide.

"It is fascinating to see how people approach different problems from different angles, and we can learn so much from each other," he said.

"I remember working with Kazakhstan many years ago to improve the adaptation of wheat.

"It was obvious the lack of diversity for leaf rust resistance severely penalised farmers in the disease-prone years. They had long accepted that this was part of farming.

"The introduction of simple rust resistance made an enormous difference! Suddenly, there was the realisation that yield losses to rust (which always occurred in the better, wetter years) no longer had to be endured."

One of Dr Trehowan's most memorable experiences from his overseas work was when he was Asia's Generation Challenge Program wheat coordinator.

"We decided to concurrently introduce marker-assisted recurrent selection for drought tolerance in India and China," he said.

"This entailed working with several successful wheat breeding programs in each country to implement the concept - we decided on this route because of the genetic complexity of drought tolerance and the abject failure of marker-assisted backcrossing strategies to produce results.

"While the science was great and, I believe, led to completely different thinking about breeding strategy and the integration of molecular technologies, the most memorable aspect was working with the local breeders in such different countries.

"Each group tackled the problems associated with implementation in different ways.

"Sometimes, intent was lost in language.

"While I could communicate with the Indian scientist directly, this was done through a translator in China."

He learnt a valuable lesson: never use a translator who doesn't understand the science.

"It wasn't until 12 months later that I discovered my Chinese colleagues heading off down the wrong path and probably wondering what this crazy foreigner was on about!" he said.

Dr Trethowan recently won the prestigious Farrer Memorial Medal for his contribution to wheat genetic improvement, benefitting the Australian and global industry.

"For me, this was a particular honour," he said.

"Farrer, a wheat breeder, established the basis for a successful wheat industry in our country.

"I've been a wheat breeder/pre-breeder/scientist over my career, so this award holds special significance."