Transcriptome analysis of floral scent biosynthesis during Michelia alba (cempaka putih) flower development

V. Maheswary1, S. Sanimah2, H.N. Khairun2, Y. Nurul Aishah2, O. Qistina2 and S. Vasanthi2

Abstract
Despite a long history of cultivation of Michelia alba (cempaka putih) and the commercial importance of its essential oils, no information is currently available on potential changes in the expression of genes involved in the synthesis of individual volatile organic compounds (VOCs) during flower development. Here we describe the combined use of Digital Gene Expression (DGE) and chemical analysis (from a previous study) to discover genes for the VOCs biosynthesis pathways and related genes. From the DGE sequencing data, a total of 50 genes (including isoforms) were identified to be involved directly with fragrance
biosynthesis from the pooled early stages (S1 – S6) and pooled late stages (S7 – S11) of flower development. Our transcriptome data revealed that the bulk of floral scent genes (29) in this species belonged to the isoprenoids biosynthesis pathway of which 15 transcripts belonged to the monoterpeoids biosythesis
pathway, seven belonged to the sesquiterpenoids biosythesis pathway while the remaining seven belonged to the terpenoids backbone biosynthesis pathway.
Fifteen genes were also identified to be involved in the biosynthesis of aromatic compounds in the phenylpropanoids/benzenoids biosynthesis pathway while six were found to belong to the fatty acid derivatives biosythesis pathway. Four other other genes were also identified to be related to floral scent biosynthesis in other metabolic pathways.

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