Analysis of cis-regulatory elements involved in the activation of a member of chalcone synthase gene family (PsCHs1) in pea

Cis-regulatory elements involved in the activation of the plant defense- related gene encoding chalcone synthase 1 (PsChs1) in pea (Pisum sativum L.) were examined by transient transfection, gel mobility shift assay and in vitro DNase I-footprinting analysis. Transient transfection assay revealed that a 61 bp DNA fragment spanning from -242 to -182 of PsChs1 was required for the maximal promoter activity and possibly involved in the enhancement of elicitor-mediated activation. Nuclear isolate from elicitor-treated pea epicotyl tissues contained some factor(s) that specifically bound to this DNA fragment to form a complex with low mobility (LMC, low mobility complex) in gel mobility shift assay. DNase I-footprinting analysis of LMC revealed that among three protected regions detected in a 61 bp DNA fragment, two regions contained identical AT-rich sequence, TAAAATACT. Site directed mutation in either or both identical sequences, TAAAATACT to TGGAATACT, resulted in the reduction or loss in the ability to form LMC. Detailed analysis of 61 bp DNA fragment demonstrated that the region from -242 to -226 containing promoter- distal TAAAATACT motif was imperative for the maximal elicitor-mediated activation of PsChs1.