Phosphoinositide-specific phospholipase C signalling mediates expression of two phenylalanine ammonia lyase genes induced by salicylic acid in Capsicum chinense cells

Abstract

The role of salicylic acid (SA) in the plant stress response is mediated by phenylalanine ammonia lyase (PAL), a key enzyme in the phenylpropanoid pathway in Capsicum chinense cells. However, the relationship between PAL expression in response to SA and the precise involvement of the phosphoinositide-phospholipase C (PI-PLC) transduction pathway linking these effects remains unclear. A pharmacological approach was used to investigate the role of the PI-PLC pathway in the transcriptional regulation of two different PAL gene members in C. chinense suspension cells exposed to SA. Two putative C. chinense PAL genes (CchPAL1 and CchPAL5) were identified after clustering as an independent group in a phylogenetic tree built with 67 Solanaceae genes, corresponding to six species. The expression of CchPAL1 and CchPAL5 showed differential patterns in C. chinense cells exposed to salicylic acid. Moreover, PLC inhibitors, such as neomycin and U73122, differentially modified the expression profiles. These findings suggest that the PI-PLC pathway participates in the activation of preferred PAL genes in response to SA in Capsicum cells.