Genes uniquely expressed in vegetative and potassium chlorate induced floral buds of Dimocarpus longan

Potassium chlorate (KClO3) induced flowering of Dimocarpus longan is a highly effective method for off-season fruit production in Southeast Asia. To begin to understand the molecular basis for longan flower induction, the suppression subtractive hybridization (SSH) technique was used to isolate genes that are differentially expressed in vegetative buds, or in KClO3 induced floral buds. Repetitive rounds of cDNA differential subtraction screening, followed by reverse northern, northern blot analysis and nucleotide sequence determination identified 65 unique genes differentially expressed in vegetative and floral buds. Many of the identified genes have been previously demonstrated to be associated with shoot and floral meristem in Arabidopsis, including Protodermal Factor 1 (LVFS-205), SHEPHERD (LVFS-100) and PISTILLATA (LVFS-199) homologs. These gene sequences validate the results of SSH procedure and represent new nucleotide sequences in longan. Hybridization of clones to different size transcripts that encode fructose-bisphosphate aldolase (LVFS-230), histone H3 (LVFS-44, LVFS-172), malonyl-CoA (LVFS-48) and SAM (sterile alpha motif) containing proteins (LVFS-290) suggest specific members of gene families or alternative splicing of RNA may be involved in longan flowering. Novel gene products not previously associated with flowering have been also identified including carbon catabolite repressor (CCR4)-associated factors (LVFS-323), SAM proteins (LVFS-290), and Notchless-like proteins (LVFS-65). These cDNA sequences represent proteins with potential regulatory roles in longan flowering.