BREAKTHROUGH research by the University of WA could open up more opportunities for finding drought tolerant wheat varieties.
Plant geneticist and plant breeder Guijun Yan, from UWA's School of Agriculture and Environment and Institute of Agriculture, led the world-first research to develop climate ready crops that are adapted to water stress.
His research focused on terminal drought tolerance - where dry conditions occur later in the growing stage from booting to flowering when plants undergo reproduction.
Professor Yan said drought was a big problem in WA farming and across the world due to climate change and global warming, which led to an increased instance of drought.
"Therefore we are doing major research into drought tolerance mainly because we don't have irrigation options in WA," Professor Yan said.
"The only way to solve the problem is to grow plants that are tolerant to drought conditions."
He said it had long been established that drought damaged the male gametes in wheat reproduction, but little was known about its affect on female gametes.
"Traditionally people have looked at this process and thought that the male part is mainly affected by drought because the male part is exposed," he said.
"Drought conditions impact on pollen availability and low pollen availability means low fertilisation, which means lower seed set."
As part of the research, water was withheld during the reproductive phase, meiosis, in 46 different wheat varieties from Australia and overseas, to examine what effect the induced drought had on the viability of male and female reproductive parts of the plant.
Grain number was used to measure the effect of drought stress.
Professor Yan said the results indicated that both the male and female parts were sensitive to water stress during meiosis, not just the male part as was previously thought.
"We identified for the first time that the stressed female reproductive part was one of the major contributors to low grain numbers in wheat varieties that were water-stressed during meiosis," he said.
"Australian wheat is generally reasonably drought tolerant because of the environment under which they were selected but there are some extreme genotypes from overseas that are more tolerant and can be incorporated into our germplasm for further breeding."
This could have ramifications for conventional wheat plant breeding as traditionally the best male traits have been chosen, whereas the research could see female traits also playing an important role in developing drought-tolerant varieties.
"Based on the results of this study, we can conclude that selective screening of grain numbers for parental lines that are tolerant to water stress during meiosis is a promising way to breed superior drought tolerant wheat."
Since being published in the scientific journal Frontiers in Plant Science recently, the findings have attracted national and international attention from plant geneticists and breeders as they could have major implications in selecting parental lines.
"The conceptual change will make us target wider genetic resources and in our research we did find some female drought tolerant types that could be directly used for plant breeding and pre-breeding," he said.
"We need to widen the research to search wider to find better genotypes for drought tolerant breeding - it is very exciting research and the first of its type published in the world."
He said the research has opened the door to exploring exactly what is causing plants to trigger a response to drought.
"We have a theory that it's not only the physical exposure of the males that is being affected but a biochemical effect on the plants - they have their own dynamic and we feel it's a signal transaction where the plant senses an environment such as drought and sends signals to set or abort seeds.
"Some wheat lines might be less sensitive to the signal or more tolerant to drought and they will keep on growing by using other resources to support seed set and seed development - figuring this out and which genes are controlling this will be our next step."
