Transcriptome Analysis Reveals Genes Related to Floral Development in Chrysanthemum Responsive to Photoperiods

This research used the cDNA-AFLP technique to identify differentially expressed transcript-derived fragments (TDFs) in the apical tips of chrysanthemum induced by different photoperiods. Of the 3,152 TDFs screened by 64 primer recombinations, 861 were found to be differentially expressed, with 597 up-regulated and 264 down-regulated. We successfully cloned, sequenced, and analyzed the homologies of 57 TDFs. We found homologies for 37 of them in the NCBI: 31 displayed homology to genes with known functions, 3 to genes with unknown function, and 3 showed no matches. Functional analysis indicated that 34 TDFs participated in seven processes: transcription regulation, signal transduction, substance and energy metabolism, differentiation and development, protein degradation and synthesis, stress responses, and unclassified protein. Semi-quantitative RT-PCR analysis with selected transcripts of four genes related to floral development indicated that they all were expressed or up-regulated under short-day conditions. This was supported by analysis of cDNA-AFLP.