Analysis and Characterization of MADS-box Genes from Davidia involucrata Baill. and Regulation of Flowering Time in Arabidopsis

Davidia involucrata Baill. is a deciduous perennial tree. MADS-box genes are widely distributed in nature and play a key role in the growth and development of plants, especially in regulating the development of floral organs. In the present study, we have used transcriptomics to select 14 MADS-box genes differentially expressed in bract and leaf, followed by cloning and preliminary bioinformatics analysis. We predict that DiMADS-1 and DiMADS-2 belong to AGL and FLC respectively. Two key genes specifically expressed during Davidia involucrate flower development, DiMADS-1 and DiMADS-2, were transformed into Arabidopsis thaliana. Flowering appeared earlier in DiMADS-1 transgenic plants than in the wild type, whereas expression levels of some flowering promoters increased. DiMADS-2 transgenic plants were shorter and flowering was delayed, consistent with an increase in expression of flowering inhibitory factors and a decrease in flowering promoting factors. Subcellular localization displayed that both gene products were located in the nucleus. These results suggest that these two genes are involved in Davidia involucrata flowering time regulation.