Transcriptomic Analysis of the Candidate Genes Related to Aroma Formation in Osmanthus fragrans

Abstract

Osmanthus fragrans, or “RiXiangGui”, is an ornamental, woody, evergreen plant that is cultivated widely because it blooms recurrently and emits a strong fragrance. Recently, the germplasm resources, classification, and aroma compositions of O. fragrans have been investigated. However, the molecular mechanisms of the floral scent formation and regulation have remained largely unknown. To obtain a global perspective on the molecular mechanism of the aroma formation during blooming, nine RNA Sequencing (RNA-Seq) libraries were constructed from three flowering stages: The initial, full, and final flowering stage. In short, a total of 523,961,310 high-quality clean reads were assembled into 136,611unigenes, with an average sequence length of 792 bp. About 47.43% of the unigenes (64,795) could be annotated in the NCBI non-redundant protein database. A number of candidate genes were identified in the terpenoid metabolic pathways and 1327 transcription factors (TFs), which showed differential expression patterns among the floral scent formation stages, were also identified, especially OfMYB1, OfMYB6, OfWRKY1, and OfWRKY3, which could play critical roles in the floral scent formation. These results indicated that the floral scent formation of O. fragrans was a very complex process which involved a large number of TFs. This study provides reliable resources for further studies of the O.fragrans floral scent formation.

The chromosome-level quality genome provides insights into the evolution of the biosynthesis genes for aroma compounds of Osmanthus fragrans

“…Recently, a set of genetic markers was identified 14 , 15 , and an effort to construct a genetic linkage map was reported 16 . Additionally, several transcriptomics studies identified a large number of genes that are differentially expressed in some of the cultivars with attractive traits 17 , 18 . While these studies indirectly associate the diverse phenotypes with the genotypes of sweet osmanthus, there is no genome information that can directly link the specific genes to particular traits.…”

“…fragrans has been examined through aroma compounds 4 – 6 , essential oils 7 – 10 , and taxonomy using various molecular markers 11 – 16 . Transcriptome studies have determined the genes that might be responsible for the emission of flower scent in O. fragrans 17 , 18 . Gene expression has also been modulated at different flowering stages of O .…”

Genome-wide miRNA analysis and integrated network for flavonoid biosynthesis in Osmanthus fragrans

“…It is usually served as an additive in food, tea and other beverages [ 17 , 18 ], and the flower oil of O. fragrans has a mildly sedative effect on controlling the energy balance of the body in terms of the prevention of over-eating and gaining weight [ 18 – 20 ]. Though many studies about O. fragrans development and application have been reported in the recent years [ 18 , 19 , 21 – 26 ], there is no study reported to address the genome-wide identification of the microRNAs in O. fragrans, which impeded the comprehensive understanding of the regulation networks during O. fragrans development. Therefore, entirely identifying the miRNAs and analyzing their functions in O. fragrans can further provide important additional information about the regulatory mechanisms in the biological processes of O. fragrans and will be useful to isolate high-quality and native medical or economical products from O. fragrans .…”

Genome-Wide Identification, Classification, and Expression Profiling Reveals R2R3-MYB Transcription Factors Related to Monoterpenoid Biosynthesis in Osmanthus fragrans

“…OfRPB2 was used as internal normalization for different flowering stages [31]. The qRT-PCR data were determined with the method described in Yang et al [32].…”