cDNA-AFLP transcriptional profiling reveals genes expressed during flower development in Oncidium Milliongolds

The flower developmental process, which is crucial to the whole lifecycle of higher plants, is influenced by both environmental and endogenous factors. The genus Oncidium is commercially important for cut flower and houseplant industry and is ideal for flower development studies. Using cDNA-amplified restriction fragment length polymorphism analysis, we profiled transcripts that are differentially expressed during flower development of Oncidium Milliongolds. A total of 15,960 transcript-derived fragments were generated, with 114 primer sets. Of these, 1248 were sequenced, producing 993 readable sequences. BLASTX/N analysis showed that 833 of the 993 transcripts showed homology to genes in the NCBI databases, exhibiting functions involved in various processes, such as signal transduction, energy conversion, metabolism, and gene expression regulation. The full-length mRNAs of SUCROSE SYNTHASE 1 (SUS1) and LEAFY (LFY) were cloned, and their expression patterns were characterized. The results showed that the expression levels of SUS1 and LFY were similar during flower development. To confirm the function of SUS1 in flower buds, carbohydrate content and sucrose synthase activity were determined. The results showed that changes in sucrose content and sucrose synthase activity reflected SUS1 expression levels. Collectively, these results indicate that SUS1 influences flower development by regulating LFY expression levels through changing the sucrose content of flower buds.