Soybeans, Charcoal Rot and Solutions

Seeking alternative approaches in development of resistant soybean varieties to increase production yields.

Dr. Shawn Brown, assistant professor of Biological Sciences, was recently awarded a renewal grant from the Mississippi Soybean Promotion Board to investigate a major soybean pathogen toward the development of alternative soybean breeding targets. This project, “Impacts of charcoal rot (Macrophomina phaseolina) epidemiology on drought resistant soybean cellular metabolism and accompanying tissue microbiome for identifying alternative breeding targets under increasing environmental stress,” is in collaboration with Mississippi State University.

One of the major concerns for soybean producers is yield loss due to plant disease. One of the most problematic diseases of soybean is charcoal stem rot, caused by the fungal plant pathogen Macrophomina phaseolina(MP). This pathogen is directly responsible for yield losses of over 40 million bushels annually in the Unites States.

Unlike many other diseases of soybean, breeding for disease resistance has not been successful for charcoal rot because the pathogen attacks multiple pathways controlled by several plant genes. Further, MP is adapted for drought and heat conditions, so with a warming world, charcoal rot incidences are expected to increase, and additional tools will be needed to be developed to protect soybeans from charcoal rot.

This project will investigate the impacts of charcoal rot exposure on soybean microbiomes, metabolites, and reactive oxygen species using a controlled greenhouse experiment across a spectrum of drought susceptibility of soybean genotypes. By understanding how MP interacts with soybeans on cellular and microbiome levels, and by monitoring disease progression over time, we can begin to develop a model for soybean-MP interactions. Unique combinations of metabolites and plant-associated fungi and bacteria that are associated with reduced disease pathogenicity will be identified. These will be examined for disease prevention capabilities.

If breeding for disease resistant cultivars is not feasible, perhaps instead of breeding for resistance, breeding for associations of plant-protective microbiomes can be an alternative approach for plant protection. Using this approach to understand concurrent physiological, metabolic, and protective microbial changes during the infection process by MP, informed targets for plant breeding can be generated toward the development of charcoal rot protection in soybean. Results from this work can provide alternative approaches in targeted development of resistant soybean varieties in the future, which will increase production yields.

To learn more, contact Brown at spbrown2@memphis.edu.