Plant Innate Immunity against Necrotrophic Pathogens

Purdue University, West Lafayette IN

Investigators

Abstract

Necrotrophic pathogens cause diseases by killing plant cells during early stages of infection to extract nutrients from dead plant cells for pathogen growth and proliferation. To induce plant cell death, necrotrophic pathogens release toxins, reactive oxygen species and hydrolytic enzymes into plant tissues. Plant immune responses against necrotrophic pathogens involve defense mechanisms such as production of antimicrobial compounds and suppression of pathogen-induced cell death. How distinct defense responses are coordinately regulated in plant cells is poorly understood. Arabidopsis WRKY33 transcription factor is important for plant resistance to necrotrophic pathogens. Plants lacking a functional WRKY33 gene display greatly increased susceptibility to necrotrophic fungal pathogens Botrytis cinerea and Alternaria brassicicola. As a transcription factor, WRKY33 regulates plant nuclear genes involved in defense responses. In addition, WRKY33 physically interacts with proteins involved in chloroplast transcription and autophagy, a protein degradation pathway critical for nutrient recycling and cell survival. This research will analyze the regulation, functions and coordination of the WRKY33, chloroplast transcription and autophagy pathways in plant defense against necrotrophic pathogens. The investigators will continue functional analysis of WRKY33-interacting chloroplast transcription factors in plant resistance to necrotrophic pathogens. The investigators will examine activation, roles and action mechanisms of autophagy in promoting plant cell survival during responses to necrotrophic pathogens. In addition, the investigators will analyze functional interactions of the three pathways required for an integrated immune response to necrotrophic pathogens. Progress in these studies will help establish a comprehensive plant immune system against necrotrophic pathogens. This knowledge is necessary for development of new and novel strategies for controlling necrotrophic pathogens, which cause many devastating diseases in crop and forest plants. The project will provide training for both graduate and undergraduate students, including students underrepresented in sciences.