Molecular characterization of lupeol synthase in pepper: identification, expression analysis and evaluation of response to elicitation

Lupeol is a pentacyclic triterpene found in fruit, vegetable as well as in several medicinal plants. This compound shows interesting pharmacological activities including anti-inflammatory, anti-tumor, anti-mutagenic and anti-malaria properties. Moreover, it has been demonstrated that dietary supplementation of lupeol prevents cancer, coronary, and hepatic diseases. Lupeol biosynthesis occurs in the citosol through the mevalonate (MVA) pathway that leads to the formation of 2,3-oxidosqualene, which is then cyclized in lupeol by lupeol synthase. In this work, the full-length cDNA of a lupeol synthase, designated CaLUP, was isolated from pepper (Capsicum annum L.). The CaLUP open reading frame consisting of 2271 bp was predicted to encode a protein of 756 amino acid residues. The comparative and phylogenetic analysis of CaLUP showed that this protein is closely related to other plant lupeol synthases, sharing 66-90% identity with their amino acid sequences. In particular, a high degree of identity (80%) was observed with lupeol synthase of Solanum tuberosum. Genotype-and tissue-specific expression patterns of the CaLUP were determined by quantitative real-time PCR analysis (qRT-PCR). In silico promoter analysis of CaLUP identified distinct cis-regulatory elements; some of these were selected to investigate their function in elicitor-induced plant response. For functional analysis, the cDNA clone containing the full-length ORF of the putative lupeol synthase is being cloned into the expression vector pYES2, and will be transformed into the yeast mutant strain GIL77.