Purdue researchers have identified two soybean genes that are resistant to a Phytophthora root and stem rot-causing pathogen, the University said Thursday.
The pathogen, Phythophthora sojae, instigates Phytophthora root rot, which can cause lesions that move up the stem and kill the entire soybean plant, thus resulting in about $250 million annually in lost yield. Even in normal crop years, pathogen is responsible for 8-15% crop loss nationwide, according to Purdue.
Because of the significant impact the resulting disease has on soybean crops, researcher Jianxin Ma, a soybean geneticist in Purdue's Department of Agronomy, said the discovery could potentially result in an annual net increase in soybean production. And it's timely, too – previously identified resistant genes have already been rendered ineffective due to the pathogen's immunity.
Although there is potential for Phytophthora sojae to become immune to the newly discovered genes, the two new genes appear stronger than most earlier genes and could remain viable for many more years, Ma said.
Researchers note also that the pathogen itself will likely be weakened as the genes are concentrated against it.
"Every time a pathogen overcomes resistance in its plant host it has to give up something itself," Teresa Hughes, cooperating researcher and U.S. Department of Agriculture plant pathologist, said. "So if it turns out that in order for the pathogen to overcome this new resistance it ends up having a fitness penalty – for instance, it can't compete as well or it doesn't survive as long in the soil – then these genes will last longer.
To identify the genes, researchers developed molecular markers that were used to speed up the process of moving resistant genes to soybean cultivars.
"These markers allow rapid pyramiding of multiple resistant genes into a single cultivar in order to boost the effectiveness of resistance," Ma explained.
Researchers must now field-test the cultivars before making them commercially available, but the discovery provides farmers with something to look forward to.
"This has the potential to provide a higher profit margin for soybean farmers, as well as reducing the use of harmful chemicals and promoting a cleaner environment," Ma said.
The research was published online by Theoretical and Applied Genetics and is to appear in the journal's November print edition.