Cloning and sequence analysis of a homologous linalool synthase gene involved in floral scents in Osmanthus fragrans var. thunbergii.

In this study, a full length cDNA encoding linalool synthase was successfully cloned from floral organs of Osmanthus fragrans var. thunbergii with newly designed degenerate primers by reverse transcription (RT)-PCR, Rapid Amplification of cDNA Ends (RACE) technology, and Blastn analysis. The gene was named as OfLis ( Osmanthus fragrans var. thunbergii linalool synthase) and deposited under GenBank accession No. FJ645727. The OfLis full length cDNA was 2 003 bp and contained a complete open reading frame (ORF) of 1 731 bp encoding 576 amino acids. Sequence analysis showed that OfLis presented two typical conserved motifs of terpene synthases, i.e DDXXD and (N, D)D(L, I, V)X(S, T)XXXE, which are essential for substrate binding and ionization. There was a N-terminal peptide sequence RR(X) 8 W which is essential for the enzymatic activity of many monoterpene synthases. The molecular weight and isoeletric point of OfLis were predicted to be 67.29 ku and 5.26, respectively. Most of the amino acid sequences of OfLis were hydrophilic regions. At the amino acid sequence level, OfLis exhibited the highest similarity (63.6%) with Lavandula angustifolia linalool synthase, and the lowest similarity (19.0%) with Clarkia concinna linalool synthase gene. RT-PCR analysis revealed that OfLis was specifically expressed in petals, pistils and stamens, but not in sepals and leaves in the whole bloom stage. This study lays a scientific basis for breeding, improvement and regulation and control of flavor profile of fragrant plant varieties.