ROLE OF A STRESS-RESPONSIVE MAP KINASE IN REGULATING ETHYLENE SIGNALING AND DISEASE RESISTANCE IN RICE

Emerging evidence suggests that ethylene (ET) and its antagonistic interaction with abscisic acid (ABA) may play a more crucial role than salicylic acid (SA) and jasmonic acid (JA) in rice disease resistance. It was proposed that flood- or hypoxia-induced ET biosynthesis in rice is critical for field resistance and management of rice blast disease (Magnaporthe oryzae) in the southern U.S. To determine the role of ET biosythesis and signaling in rice disease resistance, we generated a number of transgenic rice lines impaired in ET biosynthesis or signal perception. Transgenic analysis suggests that a stress-responsive rice MAP kinase (OsMPK5) is a negative regulator of disease resistance as well as ET biosynthesis and signaling. To gain further insight into the OsMPK5-mediated signaling pathway, a combination of genetic, molecular, biochemical and proteomic methods will be used to study how OsMPK5 may regulate ET biosynthesis and signal transduction. A better understanding of the ET-mediated disease resistance in rice will help improve breeding strategies and cultural practices for effective disease control. Since rice is an important model for monocots, the data and discovery from this study may have broader impacts on other cereals, turf grasses and biofuel crops important to the U.S. agriculture.