Volatile constituents and floral transcriptome analyses provide new insights into fragrance biosynthesis of Vanda 'Tan Chay Yan'.

Vanda 'Tan Chay Yan', a beautiful golden-orange orchid with mild fragrance, is valuable in the floral industry. In this study, the volatile compounds from the flowers were profiled and a transcriptome library was created to search for fragrance-related transcripts. Volatiles from the tepals were captured using a SPME device with PDMS-coated fibre for GC-MS analysis. A transcriptome library was constructed and sequenced using the Illumina MiSeq Desktop Sequencer, de novo assembled using CLC Genomic Workbench version 6.0. BLASTx analysis, functional annotations and gene mapping of the annotated genes to the KEGG database were carried out using the Blast2go Pro software. Twelve compounds were identified in the volatiles including monoterpenes (93.19%), sesquiterpenes (4.32%) and traces of other compounds (2.49%) whereby cis-β-ocimene topped the list as the major constituent (88.41%). De novo assembly of the transcriptome generated a total of 34,027 sequences from which 20 fragrance-related transcripts in the terpenoid and benzenoid/phenylpropanoid biosynthetic pathways were identified. Combined information garnered from the volatiles and fragrance-related transcripts highlights the basic information on the fragrance constituents and biosynthetic pathways of this orchid which are useful for orchid breeders in selection of parents for new hybrids with fragrance as their value-added characteristic for the floriculture industry. [ABSTRACT FROM AUTHOR]