Transcriptome Dynamics And Functions Of RhIAA16 Genes During Rose Petal Abscission

Rose is one of the most important commercial flower in the world. Petal abscission seriously limits its production and distribution. In an effort to acquire a functional genomic resource and give an insight into the molecular mechanisms related to rose petal abscission, we performed large-scale transcriptome sequencing of rose plants [Rose×chinensis Jacq,’Gold Medal’] of petal abscission zones of different flower stages using the Illumina sequencing technology, and selected one AUX/IAA family member RhIAA16 to analyze its role in abscission pathway. Silencing RhIAA16 by virus-induced gene in rose ’Samantha’ petal abscission and ovexpession in Arabidopsis, analysis that functions of RhIAA16 genes in petal abscission.The main results of the study are as follows:1) The anatomic observation of rose petal abscission zone showed that the petals gradually narrowed at base along with the flower unfolds, and cells of the abscission zone became larger. The cell wall got thinning and gaps between cells got larger.2) Three cDNA libraries constructed from mRNAs of different flower stage (GM1, GM3, GM5) petal abscission zone were sequenced by Illumina technology.We have acquired the number of 75752884 reads and de novo assembled into 80226 unique transcripts which were further extensively annotated by comparing their sequencing to different protein databases. We also have predicted some biochemical pathways from these transcript sequences.3) The gene expression profiling were obtained which analysis upon different flower stage petal abscission zone and had screened 2571 differential expressed genes, including 150 transcription factors and 173 protein kinases, as well as many well-known organ abscission genes. Gene ontology (GO) term enrichment and biochemical pathway analyses indicated that petal abscission separation may be related to the regulation of hormone biosynthesis and signaling, stabilization of cell proteins and structures, starch and source metabolism, synthesis and degradation of cell wall hydrolases.4) RT-PCR analysis showed that RhIAA16 mainly expressed in all the parts of the flower organs, but strongly expression in abscission. RhIAA16 was mainly expressed in petal abscission active stage in various rose, decreased at shedding stage. Flower shedding of RhIAA16-overexpressed Arabidopsis was later than WT arabidopsis.5)Silencing RhIAA16 by virus-induced gene silencing in rose promoted petal abscission, flowers fall off 5 d in advance compare with control(TRV), suggesting that RhIAA16 plays an important role in rose petal abscission.Our transcriptomic data provide us an important tool to study rose petal abscission, offer a valuable resource for rose breeding and research, and supply candidate genes or markers that can be used to guide future efforts attempting to breed petal abscission delayed rose cultivars, such as RhIAA16 may be play an important role in rose petal abscission.