Oral Technical Session: Bacterial Virulence Mechanisms 2

72-O

Do JAZs restrict/assist pathogen entry via stomata?
N. OBULAREDDY (1), M. Melotto (1)
(1) University of Texas-Arlington, Arlington, TX, U.S.A.

Previous studies have shown that stomatal pores in the leaf epidermis close as a part of the plant innate immune response against bacterial invasion of plant tissues. Counteracting this response, the plant pathogenic bacteria Pseudomonas syringae pv. tomato strain (Pst) DC3000 has evolved the virulence factor coronatine as an important strategy contributing to pathogenesis. Two components of the coronatine receptor complex, namely COI1 (the F-box subunit of E3 ligase) and JAZ (a repressor of jasmonic acid pathway) proteins, are known to regulate the jasmonic acid (JA) pathway, influencing the disease outcome. In this study we first focused on determining the tissue specific expression of JAZ3/4/9 transcripts. Our results indicate that not only JAZ4 and JAZ9 are more abundant in guard cells as compared to whole leaves; these genes are also induced by coronatine in guard cells in a dose dependant manner. For a robust insight of the modulation of these proteins by coronatine, bacterial inoculation experiments with Pst DC3000 and DC3118 were performed on the T-DNA insertion and transgenic lines of different JAZ4 and JAZ9 constructs. Our findings suggest that the N- terminus of these proteins is essential to develop resistance against Pst DC3000 in Arabidopsis. This study highlights the role of JAZ proteins in stomatal and apoplastic immunity against bacterial diseases.