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(E)-β-Caryophyllene is a sesquiterpene compound widely distributed in plants and functions in plant defence. However,little is known about the sequence and function of(E)-β-caryophyllene synthase in lima bean(Phaseolus lunatus). Here,we report a new full-length c DNA(Pl CAHS) encoding(E)-β-caryophyllene synthase,a possible key enzyme of plant defence. The c DNA of Pl CAHS contains an open reading frame of 1 761 bp,encoding a protein of 586 amino acids with a predicted mass of 67.95 k Da. The deduced amino acid sequence shows 52% identity with sesquiterpene synthase Mt CAHS of Medicago truncatula. Based on phylogenetic analysis,Pl CAHS is classified as the terpene synthases(TPS)-a subfamily. The recombinant enzyme,expressed in Escherichia coli,catalysed the formation of a major product(E)-β-caryophyllene(82%) and a minor product α-humulene(18%) from farnesyl diphosphate. Real-time quantitative PCR(q RT-PCR) analysis found that the Pl CAHS transcript was significantly up-regulated in leaves after treatment with spider mites and alamethicin(ALA),suggesting its ecological function in plant defence.
(E) -β-Caryophyllene is a sesquiterpene compound widely distributed in plants and functions in plant defense. However, little is known about the sequence and function of (E) -β-caryophyllene synthase in lima bean (Phaseolus lunatus). Here, we report a new full-length c DNA (Pl CAHS) encoding (E) -β-caryophyllene synthase, a possible key enzyme of plant defense. The c DNA of Pl CAHS contains an open reading frame of 1 761 bp, encoding a protein of 586 amino acids with a predicted mass of 67.95 k Da. The deduced amino acid sequence shows 52% identity with sesquiterpene synthase Mt CAHS of Medicago truncatula. Based on phylogenetic analysis, Pl CAHS is classified as the terpene synthases (TPS) -a subfamily . The recombinant enzyme, expressed in Escherichia coli, catalysed the formation of a major product (E) -β-caryophyllene (82%) and a minor product α-humulene (18%) from farnesyl diphosphate. RT-PCR) analysis found that the Pl CAHS transcript was significantly up-regulated i n leaves after treatment with spider mites and alamethicin (ALA), suggesting its ecological function in plant defense.