Roles of the GA-mediated Gene Family and miR156 in the Floral Development of Chinese Chestnut ().

Chestnut () is a deciduous tree species with major economic and ecological value that is widely used in the study of floral development in woody plants due its monoecious and out-of-proportion characteristics. Squamosa promoter-binding protein-like () is a plant-specific transcription factor that plays an important role in floral development. In this study, a total of 18 genes were identified in the chestnut genome, of which 10 genes have complementary regions of . An analysis of the phylogenetic tree of the squamosa promoter-binding protein (SBP) domains of the genes of , , and divided these genes into eight groups. The evolutionary relationship between poplar and chestnut in the same group was similar. A structural analysis of the protein-coding regions (CDSs) showed that the domains have the main function of SBP domains and that other domains also play an important role in determining gene function. The expression patterns of and in different floral organs of chestnut were analyzed by real-time quantitative PCR. Some with similar structural patterns showed similar expression patterns, indicating that the gene structures determine the synergy of the gene functions. The application of gibberellin (GA) and its inhibitor (Paclobutrazol, PP) to chestnut trees revealed that these exert a significant effect on the number and length of the male and female chestnut flowers. GA treatment significantly increased expression and thus significantly decreased the expression of its target gene, //, during floral bud development. This finding indicates that GA might indirectly affect the expression of some of the target genes through miR156. In addition, RNA ligase-mediated rapid amplification of the 5' cDNA ends (RLM-RACE) experiments revealed that cleaves and at the 10th and 12th bases of the complementary region. These results laid an important foundation for further study of the biological function of in the floral development of .