Objective Linalool synthase gene, LIS, of Dendrobium officinale was cloned. Expression patterns of the gene in flower, leaf, stem, and root at flowering stage as well as those in leaf induced by methyl jasmonate (MeJA) were determined to help decipher the monoterpene metabolism mechanism involved.
Method Full-length cDNA of D. officinale LIS (DoLIS) was cloned using RACE-PCR and RT-PCR. Physiochemical properties and amino acid homology were analyzed by ProtParam and BLAST P, and phylogenetic tree constructed by MEGA 6.0. Expressions of DoLIS in the flowers, leaves, stems, and roots of D. officinale at flowering stage, as well as those in the MeJA-treated leaves were determined by quantitative real time PCR.
Result The full-length of DoLIS was 2 844 bp with a 2 538 bp ORF encoding 845 amino acids. The protein had a molecular weight of 98.298 KD, a theoretical isoelectric point of 7.04, and an instability coefficient of 46.29. An unstable protein, DoLIS contained a conservative domain of Terpene_cyclase_plant_C1. The phylogenetic analysis showed that DoLIS was closely related to Phalaenopsis equestris (XP_02057697) and clustered in the same branch with the (s)-(+)-LIS of other species. The qPCR results on relative expression of DoLIS indicated that the highest level at flowering stage was found in the leaves. The MeJA induction produced the peak DoLIS expression, which was 3.88-fold of the original, in 5h after the treatment.
Conclusion This study cloned the full-length cDNA of DoLIS and discovered the relative expression of the gene to be significantly higher in the leaves than the flowers, stems or roots of a D. officinale plant at the flowering stage. In addition, the expression could be upregulated by MeJA induction.
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