Global Transcriptome Analysis and Identification of the Flowering Regulatory Genes Expressed in Leaves of Lagerstroemia indica

Flowering time is an important trait for ornamental plants, and flowering regulation has thus been both a focus of and challenge to researchers. Lagerstroemia indica is an important summer flowering tree in China and has been introduced abroad as a key parent of new cultivars; no previous reports have addressed the regulation of flowering time in this species. In this study, 28,567,778 x 2 reads were obtained from leaves of L. indica. A total of 37,325 unigenes were assembled with an average length of 849.56 bp, and 17,506 (46.90%) unigenes were significantly matched to known genes in the nr database of GenBank. The annotated sequences were clustered into putative functional categories using the Gene Ontology framework. Potential genes and their functions were predicted by the Cluster of Orthologous Groups analysis and Kyoto Encyclopedia of Genes and Genomes pathway mapping. A total of 115 unigenes related to flowering time control were discovered. Ten homologous genes of the CONSTANS-like (COL) gene family were identified based on transcript data. Phylogenetic analysis of the CONSTANS and COL genes from L. indica and other species grouped them into three clades. The transcriptome dataset and outcome of the analysis provide a valuable new resource for research on the functional genomics and molecular mechanisms of flowering control in L. indica.