The pepper cysteine/histidine‐rich DC 1 domain protein C a DC 1 binds both RNA and DNA and is required for plant cell death and defense response

Summary Plant defense against microbial pathogens is coordinated by a complex regulatory network. Cysteine/histidine‐rich DC 1 domain proteins mediate a variety of cellular processes involved in plant growth, development and stress responses. We identified a pepper ( C apsicum annuum ) cysteine/histidine‐rich DC 1 domain protein gene, C a DC 1 , which positively regulates plant defense during microbial infection, based on gene silencing and transient expression in pepper, as well as ectopic expression in A rabidopsis. Induction of C a DC 1 by avirulent X anthomonas campestris pv vesicatoria ( X cv ) infection was pronounced at both transcriptional and translational levels in pepper leaves. Purified C a DC 1 protein bound to both DNA and RNA in vitro , especially in the presence of Z n 2+ . C a DC 1 was localized to both the nucleus and the cytoplasm, which was required for plant cell death signaling. The nuclear localization of C a DC 1 was dependent on the divergent C 1 ( DC 1) domain. C a DC 1 silencing in pepper conferred increased susceptibility to X cv infection, which was accompanied by reduced salicylic acid accumulation and defense‐related gene expression. Ectopic expression of C a DC 1 in A rabidopsis enhanced resistance to H yaloperonospora arabidopsidis . C a DC 1 binds both RNA and DNA and functions as a positive regulator of plant cell death and SA ‐dependent defense responses.