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Russian Revolution Could Save Aussie Wheat

Adnan Riaz speed breeding wheat varieties.

Adnan Riaz speed breeding wheat varieties.

By Lee Hickey

Ancient wheat varieties that survived the Siege of Leningrad have rare genes that offer resistance to important diseases affecting Australian wheat.

The human population is expected to reach nine billion by the year 2050, and will strain global resources. Modern plant breeding and a switch to monoculture cropping has greatly improved yield and quality, but a lack of genetic variation has left crops more vulnerable to new diseases and climate change.

Fortunately, diverse landraces selected and grown by farmers prior to modern breeding are preserved in seed banks around the world. These seed could be the key to rediscovering lost diversity that could ensure a stable food supply for years to come.

Genetic Diversity Improves Wheat Production
Over the past 100 years, plant breeders in Australia have increased wheat yield on farms from 0.5 t/ha to approximately 2 t/ha. During a period referred to as the “Green Revolution” in the 1940s–60s, plant breeders achieved large gains in yield by selecting wheat varieties that were shorter. It wasn’t rocket science, but rather a simple strategy that enabled plants to produce more grain without falling over. This feature matched well with large-scale agricultural systems that use irrigation, fertiliser, pesticides and machinery.

Since this major advance in productivity, the rate of gain for farm yield has slowed to just 1% per year. This estimate includes gains from both breeding and improved management practices. It’s clear that wheat yield around the world is beginning to plateau.

Traditionally, farmers were the ones who selected crop varieties. They simply retained seed from the most productive plants to sow during the next season. These varieties, known as landraces, were adapted to the local conditions because they were the product of a combination of natural and artificial selection in a specific environment.

However, unlike modern varieties, landraces were developed under a lower selection pressure. Therefore they collectively contain higher levels of genetic diversity. Immense genetic diversity in landraces has been reported for many crops, including wheat, maize, sorghum, barley, rice and oats. Thus, landraces represent a valuable source of genetic variation for resistance to pests and diseases, and also for tolerance to environmental stresses such as heat or drought.

Seeds Preserved for Future Generations
Born in 1887, Nikolay Vavilov was a renowned Russian botanist and geneticist who was best known for his theory relating to “the centres of origin of cultivated plants”. He devoted his life to the study and improvement of wheat, corn and other cereal crops that sustain the global population.

Inspired by his idol, Charles Darwin, he travelled the world in the early 1900s, collecting more seeds, tubers and fruits than any person in history. The collections, including many wheat landraces, were stored in a seed bank in Leningrad, now known as the N. I. Vavilov Institute of Plant Genetic Resources in St Petersburg, Russia. This unique seed collection represents a snapshot of ancient wheats grown around the world prior to modern breeding.

During World War II, the “Siege of Leningrad” lasted 28 months. The German army surrounded the city, resulting in extreme famine in the region. More than 1.5 million people lost their lives. In the middle of all this was the seed bank containing 250,000 samples of seeds, tubers and fruits. Despite widespread famine, a group of scientists at the Vavilov Institute took shifts protecting them. They refused to eat the seeds, and nine of them died of starvation by the end of the siege in 1944.

The seed bank was saved, but Vavilov himself faced an ironic fate. On 6 August 1940 he was arrested for criticising the non-Mendelian concepts of Soviet biologist Trofim Lysenko, who had the support of Joseph Stalin. Vavilov was sentenced to death in July 1941, but in 1942 his sentence was reduced to 20 years imprisonment. Despite this, he died of starvation in prison in 1943.

Opening Vavilov’s Treasure Chest of Diversity
Following in the footsteps of the Russian scientist, my PhD student Adnan Riaz performed the world’s first genetic analysis of Vavilov’s wheat seeds. A total of 295 diverse wheats collected from around the world were examined using 34,000 DNA markers. The genomic analysis, which has been published in the journal Genetic Resources and Crop Evolution (http://tinyurl.com/hdd2mjt), revealed a massive array of genes that are absent in modern Australian wheat cultivars. These ancient genes could offer valuable sources of disease resistance or drought tolerance.

We are offering the research community open access to this resource, including the pure seed of the ancient wheats and DNA marker information. We hope this will empower scientists and wheat breeders to rediscover genetic diversity lying dormant in our seed banks.

Our next step is to determine which landraces are useful for particular traits and to discover new genes for disease resistance hidden in the Vavilov treasures. At the moment we are focusing on some of the most important diseases of Australian wheat crops, such as yellow spot and rust pathogens.

Yellow spot disease currently results in the highest yield losses in Australia, causing a very serious threat to the wheat industry. Yellow spot is a stubble-borne leaf disease, and thus wheat-on-wheat crop rotations and zero or minimal tillage farming practices are contributing to the build-up of inoculum in farmer’s fields.

On the other hand, rust diseases of wheat, such as stripe, leaf and stem rust, are airborne pathogens and can occur throughout most wheat-growing regions in Australia. They have the ability to mutate and render resistance genes in wheat ineffective, so wheat breeders require a constant supply of new genes to combat these rapidly evolving pathogens. Our preliminary assessment of the Vavilov wheat collection has identified a number of landraces that display resistance to both yellow spot and rust diseases.

Over the past 8 years at The University of Queensland, my colleagues and I have refined a system called “speed breeding” that uses controlled environment glasshouses fitted with lights to accelerate plant development. This technique allows up to six plant generations of wheat per year – compared with just one in the field during the main growing season. We intend to use speed breeding to rapidly transfer the new resistance genes into modern wheat cultivars currently grown by Australian farmers. This will help boost the number of effective resistance genes we have at our disposal to combat rapidly evolving pathogens that threaten wheat production.


Lee Hickey is a crop geneticist at the Queensland Alliance for Agriculture and Food Innovation, The University of Queensland.