Alternative Polyadenylation as a Major Regulatory Mechanism of Plant Innate Immunity

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Plant disease resistance (R)-genes encode immune receptors that mediate disease resistance upon recognition of pathogenic microorganisms. Their expression has to be coordinated. The investigators previously identified a new process that controls the expression of two R-genes in the model plant Arabidopsis thaliana. The main goals of this project are (1) to examine extent to which this new mechanism is utilized in plants for the regulation of additional R-genes and other defense genes and (2) to gain detailed understanding of this new mechanism. Results from this study are likely to have a broad impact on the fields of plant immunity and gene expression control. This project may also lead to the design of new strategies for enhanced disease protection in crop plants. An important component of the project is major involvement of undergraduate students, mainly from minority groups. The project will be linked to classes on biochemistry and biotechnology taught by the Principal Investigator and the ongoing NSF-REU Plant Cell Biology program within the Center for Plant Cell Biology at UC-Riverside. In addition, the project will provide a strong platform for training of postdoctoral scholars and graduate students and prepare them for careers as senior researchers in academia or industry. The goals of the America COMPETES Act of 2007 that emphasize awareness of the responsible and ethical conduct of research are a top priority of this project.Alternative polyadenylation is emerging as a major mechanism of eukaryotic gene expression control. The investigators previously found the epigenetic mark H3K9me2 to control differential use of polyadenylation signals of the Arabidopsis R-genes RPP4 and RPP7 and to modulate levels of immunity mediated by their encoded immune receptors. This mechanism is controlled by the epigenetic factor EDM2 and several additional newly identified regulators. The investigators further showed this novel mechanism to be responsive to pathogen recognition and to dynamically adjust RPP4 and RPP7 expression. The central hypothesis of this project is that alternative polyadenylation is a major mechanism controlling inducible plant immune responses. The two specific aims that are to be pursued are: 1) Genome wide profiling of alternative polyadenylation events after defense induction; 2) Identify regulatory factors linking alternative polyadenylation to pathogen perception and defense signaling. Alternative polyadenylation has so far not been recognized as a major mechanism controlling plant immunity. This project will provide a genome-wide overview about defense-associated alternative polyadenylation in plants and uncover molecular details of this type of regulatory process.