Sorghum, a more drought-tolerant cousin to corn, is grown throughout the dry western Corn Belt region of the United States. The crop is traditionally grown for the grain, but newer cultivars have been developed to maximize vegetative biomass, a key trait for lignocellulosic bioenergy production. But before sorghum can meet its full potential as a bioenergy crop, it will need to become more resistant to diseases that can reduce its ability to produce biomass.

 

With the announcement of a $1.1 million grant for sorghum disease resistance research led by the University of Illinois, the Department of Energy is signaling a new investment in the future of the crop.

Tiffany Jamann, assistant professor in the Department of Crop Sciences at U of I is the principal investigator on the grant. “Host resistance is one of the most environmentally friendly and cost-effective methods of disease control,” she says. “Developing disease resistance for bioenergy crops, including sorghum, is crucial, particularly as the range of production expands and microbes evolve from related species to become pathogens of bioenergy crops.”

 

Sorghum is susceptible to infection by the fungus that causes sorghum leaf blight, which is associated with decreased yields, reduced forage quality and quantity, and an increased risk of infection by other diseases, including anthracnose. Interestingly, the same fungus infects corn, a fact Jamann and her research partners ultimately hope to use to increase resistance in sorghum.

“By leveraging the knowledge of resistance in maize, we will accelerate the improvement of resistance to the disease in sorghum, while also developing a system to understand how microbes evolve to become pathogens of bioenergy crops,” she says.

Although the fungus can attack multiple hosts, specific strains – or isolates – can only infect corn or sorghum, not both. Jamann will look closely at how that host specificity works, both from the viewpoint of the fungus and of the plant. If she can isolate genes that control resistance to the fungus in each crop, she thinks she could eventually put those genes together in new corn and sorghum varieties, making them resistant to both strains.

“Our idea is if these genes are functional in both maize and sorghum, then they’re probably functional against other diseases, as well,” Jamann says.

Jamann will work with research partners Santiago Mideros, also from U of I, and Bill Rooney from Texas A&M University over the next three years to identify resistance genes in sorghum using approaches that harness natural genetic variation in the plant. Preliminary research has already turned up candidate genes. Next, they will test the efficacy of those genes in resisting sorghum leaf blight and anthracnose. Finally, they will investigate the fungus itself to identify genes responsible for host specificity on sorghum.

“The proactive strategy of paired identification of fungal effectors and plant resistance genes in a pathosystem with a high likelihood of producing a host jump is a paradigm shift in disease management through host resistance,” Mideros says. “This work may ultimately provide an example of how to appropriately increase the acreage of crops into a region while deploying host resistance.”