CAZFP1, CYS2/HiS2-type zinc-finger transcription factor gene functions as a pathogen-induced early-defense gene in Capsicum annuum

A pepper zinc-finger protein gene, CAZFP1, encoding the Cys(2)/His(2)-type zinc-finger transcription factor was isolated from pepper leaves inoculated with an avirulent strain Bv5-4a of Xanthomonas campestris pv. vesicatoria. The CAZFP1 protein is a nuclear targeting protein, which functions as a transcriptional regulator. The full-length CAZFP1 had no transcriptional activation activity, whereas the C-terminal region of CAZFP1 had transactivation activity. The CAZFP1 transcripts were constitutively expressed in the pepper stem, root, flower and red fruit, but were not detectable in the leaf and green fruit. The CAZFP1 transcripts accumulated earlier than the CABPR1 (PR-1) gene in the incompatible interaction of the pepper leaves with X. campestris pv. vesicatoria. The CAZFP1 transcripts were significantly induced in the systemic, uninoculated leaf tissues early after inoculation with bacterial pathogens, but gradually declined thereafter. The CAZFP1 transcripts were localized, and confined to the phloem cells of the vascular bundle in the pepper leaf midrib in response to Colletotrichum. coccodes infection, ethylene and abscisic acid. The CAZFP1 gene was also induced much earlier by abiotic elicitors and environmental stresses, compared with the CABPR1 gene. Overexpression of the CAZFP1 gene in the transgenic Arabidopsis plants enhanced not only the resistance against infection by Pseudomonas syringae pv. tomato, but also the drought tolerance. These results suggest that the CAZFP1 gene functions as an early-defense gene to enhance disease resistance and drought tolerance.