Role of Oxalic Acid and Reactive Oxygen in Sclerotinia Sclerotiorum Disease Development

Texas A&M Agrilife Research, College Station TX

Investigators

Abstract

Intellectual Merit Sclerotinia sclerotiorum is an omnivorous fungal plant pathogen with an extremely broad host range capable of producing devastating losses in economically important food crops, including soybeans, dry beans, canola and potato among many others. Over 400 species of plants are susceptible to this pathogen. Currently, there are no adequate resistance strategies against Sclerotinia diseases (culturally or chemically) and breeding for resistance to this fungus has not been successful. Annual losses of crops from diseases caused by S. sclerotiorum in the U.S. are in the multimillion dollar range. The fact that Sclerotinia is aggressive, broad in its host range, poorly controlled and causes significant economical damage, coupled with the lack of resistant cultivars necessitates the development of alternative control strategies. A molecular based mechanistic approach will be used in this project to understand why the fungus is so successful; in particular the project will examine the roles that reactive oxygen species and oxalic acid play as key modulators of fungal disease. The project is supported by recent observations that demonstrated that fungal secreted oxalate induces a programmed cell death in the plant host and recapitulates S. sclerotiorum disease symptoms. Similarly oxalic acid induces increased reactive oxygen species levels in the plant which correlate with, and are necessary for, programmed cell death and disease. Results from these studies will provide information for alternative disease control strategies based on interference with these key fungal pathogenicity determinants. Broader Impact The experiments described in this project offer broad and comprehensive training for students encompassing a number of fields. Current approaches include microbiology, plant pathology, plant biology, high throughput gene silencing screens, molecular biology and genetics. The mechanisms underlying fungal induced plant disease are both fundamental and of practical importance. This is particularly noteworthy since food safety, food contamination and food security are critically important issues nationally and internationally. This is compounded by Sclerotinia diseases since control measures (genetic and chemical) are largely ineffective. This research program will provide a unique and interdisciplinary training opportunity for a graduate student, postdoctoral fellows, and undergraduate students to participate in a critical area of stress signalling and cell death regulation, while conceptually addressing broader conceptual ideas as to how this particular group of important plant pathogens achieves pathogenic success. The project also supports summer research activities for students from Hispanic Serving Institutions and a Land Grant University in Texas.