Histone Modifications and Mediator Complex in Plant Innate Immunity to Necrotrophic Fungi

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Fungal pathogens of plants cause tremendous impacts on crop production. Particularly, necrotrophic fungi are widespread pathogens of agronomic and horticultural crops. Despite extensive studies on plant-pathogen interactions, critical components of resistance against these groups of pathogens, including mechanisms of signal recognition, transduction and activation of defenses are poorly understood. A pair of Arabidopsis RING E3 ligases, HISTONE MONOUBIQUITINATION 1/2 (HUB1 and HUB2) are key components of defense against necrotrophic fungi. The hub1 and hub2 mutants show extreme susceptibility to the necrotrophic fungal pathogens Botrytis cinerea and Alternaria brassicicola. This observation has opened an avenue for dissecting the role of chromatin modification and associated regulators in plant defense. The overall goal of this project is to dissect the role of histone modification in plant immunity with a particular emphasis on necrotrophic fungi. Knowledge of the state of chromatin modifications during pathogen infection and how this modification is accomplished is central to unraveling how plants achieve flexibility in responding to pathogens and changeable environmental conditions. How chromatin modifications are conferred on specific DNA sequences in response to particular infection and the factors that regulate it will be important to determine. The investigator seeks to establish the mechanisms that link histone H2B modification, transcriptional activators and co-activators to plant defense responses by starting from a genetically defined regulatory point of Arabidopsis immune response. The specific aims are to (1) Define the mechanisms of HUB1/HUB2 function in defense and (2) Characterize the defense and molecular functions of HUB1 interacting proteins. These two specific aims will define novel genetic components and regulatory mechanisms that govern immune responses against necrotrophic fungi.This project will provide training for students from undergraduate to post-doctoral levels in the areas of genetics, molecular biology and biochemistry. By investigating fundamental aspects of plant responses to fungi, this project will pave the way for generating genetic resistance against some of the world's most widespread and devastating pathogens. Such knowledge will also help understand how environmental signal are integrated and transmitted to the plant cellular machinery to achieve adaptive responses. A detailed knowledge of defense mechanisms against important plant pathogens can shape crop protection measures that are sustainable, environmentally friendly as well as enhancing public safety.