CaWRKY58 Encoding A Group ? WRKY Transcription Factor Of Capsicum Annuum Negatively Regulates Resistance To Ralstonia Solanacearum Infection

WRKY transcription factors are encoded by large gene families across the plant kingdom.So far,their biological and molecular functions in non-model plants,including pepper(Capsicum annuum)and other solanaceae,remain poorly understood.Here,we report on the functional characterization of a new group I WRKY protein from pepper termed CaWRKY58.Our data indicated that CaWRKY58 can be localized to the nucleus and interact in plant cells with W-box(TTGAC(C/T))promoter elements.In pepper plants infected with the bacterial pathogen Ralstonia solanacearum CaWRKY58 transcript levels show a biphasic response manifested in an early/transient down-regulation and late up-regulation.CaWRKY58 transcripts were suppressed by treatment with Methyl Jasmonate and Abscisic Acid.Tobacco plants overexpressing CaWRKY58 did not show any obvious morphological phenotypes,but supported enhanced growth of R.solanacearum strain FJC100301 and exhibited more severe disease symptoms than wild-type plants.Enhanced susceptibility of CaWRKY58-overexpressing plants correlated with reduced expression of hypersensitive response marker genes as well as various pathogenicity related genes.Consistently,CaWRKY58-silenced pepper plants by virus induced gene silence(VIGS)displayed enhanced resistance to the highly virulent R.solanacearum strain FJC100301.Our results suggest that CaWRKY58 acts as negative regulator of a set of plant defense genes required for resistance to R.solanacearum.