Functional Verification Of MdFD Gene And Expression Analysis Of Early Flower Related Genes In Apple

Flowering is one of the most important events in the life of seed plants.Studies have shown that the key genes regulating flower formation in plants are relatively conservative.The plants over expressing the Flowering Locus T(FT)or its partner Flowering Locus D(FD),a b ZIP transcription factor gene from annual herbaceous or perennial woody plant flower earlier.As a perennial woody model plant,the function of the Md FT gene in apples was identified as early as 2010,but the function of Md FD gene is still unclear.In this study,we isolated Md FD gene from ‘Gala’,and identified its functions by bioinformatics analysis,expression assay,phenotypic identification of transgenic arabidopsis,Yeast two-hybrid and bimolecular fluorescence complementarity.Besides,the expression patterns of several important flower development related genes were anlyzed in Malus baccata and early blooming Malus baccata.The main results obtained were as follows:1.Bioinformatics analysis indicated that the open reading frame of Md FD was 840 bp,which consists of 3 exons and 2 introns,and encodes a protein of 279 amino acids.The molecular weight of the protein is 30.207 k Da and the isoelectric point is 10.01.It is a hydrophilic protein.It contains a conserved b ZIP domain which has the most closely relationship with the FD protein of Eriobotrya japonica.Further analysis of the promoter region revealed that the gene promoter contains light-responsive elements,circadian rhythm control elements,and hormonal response elements,and so on.2.The results of expression analysis showed that there were two peaks of Md FD gene expression,which appeared in September and January of the following year,with low expression in April and May.3.Transformation and functional complementation confirmed that Md FD is an important early flowering gene and causes early flowering of transgenic arabidopsis.Yeast two-hybrid and bimolecular fluorescence complementation showed that Md FD protein can form homodimer and interact with Md FT1 protein.4.Real-time PCR data showed that the expression of Mb FT1,MbFD and Mb AP1 gene in early blooming Malus baccata was much higher than Malus baccata.Comparison of the promoter sequences revealed that several cis-acting elements were different between the two resources.