Cloning, expression analysis and sequence characterization of a monoterpene synthase gene, PaLis, from apricot (Prunus armeniaca)

Fruit fragrance compounds include more than a dozen chemical classes, such as organic acids, alcohols and terpenes etc. In this study, we cloned the full length cDNA encoding a linalool synthase, one of the monoterpene synthases from 'Jintaiyang' apricot (Prunus armeniaca), using RACE (Rapid Amplification of cDNA Ends) strategy. The linalool synthase gene was named PaLis, and it was expressed in fruit and flower revealed by RTPCR. The full length PaLis cDNA contained a complete open reading frame (ORF) of 1815 bp encoding 605 amino acids. The PaLis gene showed two typical conserved motives of terpene synthases, i.e DOXXD and (N,D)D(L,I,V)X(S,T)XXXE, which are involved in the coordination of divalent cations. It also displayed the N-terminal peptide sequence RR(X)(8)W which is essential for the enzymatic activity of many monoterpene synthases. Another typical motif frequently found in such enzymes is LNLYEASYHS. The molecular weight (Mw) and isoeletric point (pl) of PaLis were predicted to be 70.6 kDa and 5.34, respectively. Amino acid comparison showed that the PaLis shared 36.9% to 68.2% similarities to other monoterpene synthase genes. The PaLis sequences cloned herein provide a molecular basis for the synthesis of monoterpenoids in apricot fruit, which is useful for elevating the level of fragrance compounds and thereby improving the quality of the production.