Construction and de novo characterization of a transcriptome of Chrysanthemum lavandulifolium: analysis of gene expression patterns in floral bud emergence

Abstract

Chrysanthemum is one of the most important commercially used floral crops. The flowering feature of chrysanthemum has considerable ecological and cultural value; however, it’s flowering mechanisms has not been well characterized to date because of a lack of genomic information. In this study, we firstly present extensive sequence and transcript abundance data for the transcriptome of a key chrysanthemum-related species, Chrysanthemum lavandulifolium (Fisch. ex Trautv), which was obtained using Illumina HiSeq™ 2000 sequencing platform. There were 108,737 high quality unigenes that were assembled based on 4 GB sequencing data, of which 58,093 were annotated by a similarity search with known proteins (E-value < 1.00E−5). In total, 211 flowering-related unigenes were identified from the transcriptome of C. lavandulifolium. Furthermore, the upgraded version of the digital genes expression analysis identified 14,406 unigenes that showed significantly different expression levels between the seedling stage and the visible bud stage. Many unigenes with high similarity to important genes that are involved in the photoperiod, gibberellin, vernalization, and autonomous pathways were identified, such as CONSTANS (CO), FLOWERING LOCUS T (FT), SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1(SOC1) and FLOWERING LOCUS C (FLC). Furthermore, many more transcription factor genes, including MIKC-type, SBP and YABBY, which are specifically expressed in the visible bud stage of C. lavandulifolium, were identified for the first time. This study represents the first exploration of the C. lavandulifolium transcriptome, and these results will not only provide novel insights into the molecular mechanism of the flowering of C. lavandulifolium but can also facilitate molecular breeding in chrysanthemums.