Study : Transcriptome analysis of flower scent formation in Lilium


Transcriptome analysis of flower scent formation in Lilium
Lilium is one of the most popular flowers around the world not only because of its elegant appearance but its inviting flower scent. However, little is known about the molecular mechanism underlying flower volatile synthesis. Here, a strategy of 2-dimensional analysis was conducted in Lilium cultivar ‘Siberia’, during which the flower volatile changes and corresponding gene expression profiles at four flower developmental stages and four circadian times were captured by combining GC-MS and RNA-seq methods. Approximately 1.6 billion clean reads were totally assembled and 563,333 unigenes were obtained, of which 237,268 unigenes were annotated successfully. A total of 13,888 and 7,177 differentially-expressed genes (DEGs) were identified from the two processes. By overlapping DEGs above, an atlas with 3,434 DEGs was yielded, of which 1,273 were identified as transcriptional factors (TFs). By WGCNA (weighted gene co-expression network analysis), DEGs were further correlated to flower volatiles. Except for the homologous scent-related genes, 6 unigenes were correlated to terpenoids biosynthesis for auxin-responsive protein, acyl transferase, gibberellin-regulated proteins, gibberellin 2-beta-dioxygenase and ABC transporter. 37 TFs including 3 MYBs, may be involved in the regulation of terpene production. Three unigenes for ABC transporter, ethylene-responsive factor, arogenate dehydratase and 41 TFs (2 MYB TFs) were identified to be candidates responsible for phenylpropanoids production. To fatty acid derivatives, three ungenes for auxin-responsive proteins were identified except for 11 homologous genes in the pathways. 90 TFs, including 11 MYBs, 18 bHLHs, 7 B3s, 7 C2H2s, were identified which be involved in production of fatty acid derivatives. Altogether, this study provided an important resource and an insight into the molecular mechanism of floral scent formation in plants with a new strategy that combining the 2-D analysis and WGCNA method.


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