ELUCIDATING THE ROLES OF POLYCOMB GROUP PROTEINS IN THE REGULATION OF JASMONATE-RESPONSIVE GENES IN PLANTS

Abstract

JASMONIC ACID (JA) IS A PLANT HORMONE RESPONSIBLE FOR VARIOUS GROWTH AND DEVELOPMENT PROCESSES AS WELL AS BIOTIC AND ABIOTIC STRESS RESPONSES. IN THE MODEL PLANT ARABIDOPSIS THALIANA, JASMONATE-ZIM DOMAIN (JAZ) PROTEINS ARE THE REPRESSORS IN JA SIGNALING PATHWAY. THEY RECRUIT GENERAL CO-REPRESSORS TO INHIBIT THE TRANSCRIPTION OF JA-RESPONSIVE GENES IN THE ABSENCE OF THE HORMONE. IN THIS THESIS STUDY, IT HAS BEEN FOUND THAT JAZ PROTEINS COLLABORATE WITH POLYCOMB GROUP (PCG) PROTEINS TO REPRESS THE EXPRESSION OF JA-RESPONSIVE GENES. WE SHOW THAT SEVERAL PCG COMPONENTS DIRECTLY INTERACT WITH A FEW OF JAZ PROTEINS AS WELL AS THE ADAPTOR NINJA. IN ADDITION, WE FOUND THAT THE PHENOTYPES OF THE JA RECEPTOR MUTANT CORNATINE INSENSITIVE 1 (COI1) CAN BE PARTIALLY RESCUED BY A FUNCTIONAL LOSS OF A PCG COMPONENT. THESE AND OTHER RESULTS DESCRIBED IN THIS STUDY DEMONSTRATE THAT PCG PROTEINS COORDINATE WITH JAZS TO MEDIATE JA ACTIONS IN PLANTS.