Abstract: This work is to study the full-length gene structural characteristics and encoded protein properties of α-farnesene synthase（MdAFS）from ‘White Winter Pearmain’ apple，and analyze the induced expression patterns of MdAFS gene. Bioinformatics software was used for analyzing the MdAFS gene and its encoded protein，secondary structure，and tertiary structure，then MEGA6.0 for constructing the phylogenetic trees with AFS from different species，and qRT-PCR for studying the expression pattern of MdAFS gene. The full-length of MdAFS gene（GenBank accession number：AY563622）was 1731 bp，contained the complete ORF，encoding 576 amino acids. The prediction analysis of secondary structure and tertiary structure showed that the protein was α-helix as the main parts of the mixed type proteins. The sequence similarity of α-farnesene synthase amino acid in different species was low，but the N-terminal RRx8W and C-terminal the H-α1loop of α-farnesene synthase was highly conservative. Abiotic stress and hormones induced MdAFS expression up-regulated，and more remarkably up-regulated expressions were observed in MV，ABA and MeJA treatments. In conclusion，α-farnesene synthase in ‘White Winter Pearmain’ apple has low similarity in amino acid sequence，but similar protein 3D structure. α-farnesene synthase presents monoterpene synthases characteristics in the protein structure and function. It is revealed that the abiotic stress and hormonal signal induce the up-regulation expression of key enzyme MdAFS gene in the α-farnesene metabolic pathway in ‘White Winter Pearmain’ apple.

Key words: ‘White Winter Pearmain’ apple, α-farnesene synthase, sequiterpene volatiles, abiotic stress, expression analysis