First, scientists from the Chinese Academy of Agricultural Sciences in Beijing examined the genetic sequence of several hundred soybean varieties to pinpoint a candidate salt tolerance gene.
“We initially identified the gene by comparing two commercial cultivars,” said Professor Lijuan Qiu, who commenced the project with Dr Rongxia Guan at the academy’s Institute of Crop Sciences.
“We were surprised and pleased to see that this gene also conferred salt tolerance in some other commercial cultivars, old domesticated soybean varieties and even wild soybean.
“It appears that this gene was lost when breeding new cultivars of soybean in areas without salinity. This has left many new cultivars susceptible to the rapid increases we are currently seeing in soil salinity around the world.”
With the gene identified in Beijing, the research moved to Australia, where a team from Adelaide University began to look into its function.
“This gene functions in a completely new way from other salt tolerance genes we know about,” said Associate Professor Matthew Gilliham of Adelaide’s plant energy biology centre.
“We can now use this information to find similar genes in different crops such as wheat and grapevine, to selectively breed for their enhanced salt tolerance.”
Future breeding programmes
The findings, Gilliham believes, will have a significant impact on global food security, with salt-affected soils accounting for 8% of the world’s total land area.
Around 20% of irrigated land is salt-affected already, and it provides around 40% of the world’s food.
“Soybean is the fifth largest crop in the world in terms of both crop area planted and amount harvested. But many commercial crops are sensitive to soil salinity and this can cause major losses to crop yields,” he said.
“On top of that, the area of salt-affected agricultural land is rapidly increasing and is predicted to double in the next 35 years. The identification of genes that improve crop salt tolerance will be essential to our efforts to improve global food security.”
By identifying the gene, genetic markers can now be used in breeding programmes so that salt tolerance can be maintained in future soybean cultivars that will be grown in areas prone to soil salinity.