P-187 - Characterizing NAD Kinase 1 in Tomato-Xanthomonas Interactions

An emerging paradigm indicates that plant and animal pathogens target nicotinamide adenine dinucleotide (NAD) metabolism to interfere with central metabolism and immune response. However, the specific importance of NAD metabolites in plant immune response, and the virulence mechanisms by which pathogens manipulate these metabolites, are not well understood. Using proteomic mass spectrometry to study the effector protein XopX, we discovered that the bacterial pathogen Xanthomonas euvesicatoria utilizes the tomato enzyme NAD Kinase 1 (NADK1) during infection. Silencing expression of the NADK1 gene inhibits XopX-induced cell death and suppression of reactive oxygen species, and tomato plants which lack NADK1 protein are more resistant to X. euvesicatoria infection. We hypothesize that XopX is manipulating flux of NAD(H) to NADP(H) by forming a complex with NADK1 and altering its activity, localization, or stability. The goals of this project are to study the XopX-NADK1 interaction to determine the virulence mechanism of XopX and the roles of NADK1 and NAD metabolites in tomato immune response and X. euvesicatoria virulence. This work aims to provide fundamental insight into the regulation of NAD metabolism during immunity and a virulence strategy used by bacteria to alter metabolic homeostasis.