[Gene cloning and expression analysis of benzoic acid stress responsive transcription factor WRKY7 in Panax ginseng]

WRKY transcription factor is one of the most important transcription factor families widely existing in higher plants, which playing critical role in plant morphogenesis, development, biotic (including phytopathogens, pests etc.) and abiotic (drought, salt, chilling, high temperature, etc.) stress. In the present work, primers used to amplify full-length gene encoding WRKY transcription factor were designed based on the transcriptome data of P. ginseng that induced by benzoic acid, one of the most important autotoxins identified from root exudates and rhizosphere soil of P. ginseng. Then, a WRKY gene, temporarily named as WRKY7, was confirmed by RT-RCR. Furthermore, sequencing and sequence analysis of WRKY7 was conducted. Results indicated that, the full length cDNA of WRKY7 was 1 216 bp, the open reading frame (ORF) of which was 1 014 bp, encodes 337 amino acids. Homologous analysis and phylogenetic tree showed that, WRKY7 belonged to the Ⅲ category of WRKY families, which showing 87% similarity to WRKY6 in P. quinquefolius. Real-time PCR results showed that the expression of WRKY7 in P. ginseng induced by benzoic acid was up-regulated markedly than the control, so we speculated that WRKY7 was involved in the response to benzoic acid stress, which will be helpful for further research on the molecular mechanism of ginseng plant response to benzoic acid stress.