Elucidation of the rice innate immune response using forward and reverse genetics approaches

This dissertation consists of three distinct sections with the unifying theme of furthering our understanding of the complex network of signaling cascades that constitute plant innate immunity. Specifically, I focus on resistance mediated by NH1 and XA21. NH1 is a central regulator of rice innate immunity and is orthologous to Arabidopsis NPR1. XA21 is a pattern recognition receptor that recognizes the pathogen associated molecular pattern Ax21. XA21 and over expression of NH1 both confer resistance to the bacterial pathogen Xanthomonas oryzae pv. oryzae.;Chapter one describes a mutant screen for positive regulators of NH1-mediated immunity. I chose one mutant, snl6, to characterize in detail. Comparative genome hybridization combined with fine mapping located Snl6 to rice chromosome one. Subsequent RNAi and allelic complementation demonstrated that Snl6 is a cinnamoyl-CoA reductase-like gene. Snl6 is required for NH1-mediated resistance but not for resistance mediated by XA21.;In chapter two, I describe the development of a transient assay for protein localization and gene silencing using rice protoplasts. I describe protocols for protoplast isolation from several different tissue types including major leaf tissue. Further, I demonstrate efficient transformation as well as silencing of genes using siRNAs in the protoplasts.;Chapter three focuses on in vivo protein localization studies. I report in planta localization of XA21. In addition, I report on the localization of several XA21-interactors in rice protoplasts.