Effects Of Tomato SlCDF Gene On Flowering In Different Photo Environments

CDF?Cycling dof factors?protein is a special kind of plant transcription factor discovered in recent years,which plays a crucial role in photoperiod regulation of flowering and resistance to abiotic stress.Current studies indicate that CDF protein delays flowering as a negative regulator in Arabidopsis but fails to elucidate its function in tomato.In order to clarify the role of the SlCDF genes in regulating tomato flowering,this study used tomato?Solanum lycopersicum L.?A57 as a test material,and through the bioinformatics analysis of tomato SlCDF genes,constructed an overexpression vector and cultivated the corresponding transgenic plants.The flowering time of transgenic plants under different photoperiod conditions was measured,and the expression changes of downstream flowering related genes were analyzed,and the interaction between tomato SlCDF protein and target genes was further speculated.The staple results are as follows:1.Bioinformatics analysis of tomato SlCDF genes showed that there are five SlCDF genes located in D subfamily of Dof family together with Arabidopsis AtCDF genes,which were named SlCDF1,SlCDF2,SlCDF3,SlCDF4 and SlCDF5.At the same time,the tomato SlCDF1-5 genes consists of two exons and one intron,and the encoded protein contains a C₂-C₂ type single zinc finger domain at the N-terminus,which consists of 4 absolutely conserved Cys residues and 48 highly conserved amino acid residues;it contains a transcriptional activation domain at the C-terminus and consists of three conserved motifs consisting of 21,22 and 33 amino acid residues.2.To measure the expression of tomato SlCDF1-5,it was found that SlCDF1,SlCDF2,SlCDF3,SlCDF4 and SlCDF5 had different spatial and temporal expression differences in different tissues and organs and different leaf ages.The expression patterns of SlCDF1 and SlCDF3 in the external light environment were different with SlCDF2,SlCDF4 and SlCDF5.At the same time,in the long-day?LD?and night red light?R?interrupt treatment,SlCDF1and SlCDF3 showed opposite expressions modes under short-day?SD?and far-red?R:FR=0.6?treatments.3.The tomato A57 overexpressing S1CDF1,SlCDF2,SlCDF3,SlCDF4 and SlCDF5were obtained by Agrobacterium tumefaciens-mediated method.Three T₀ positive seedlings with relatively high expression levels were selected by PCR and qRT-PCR.Moved into the solar greenhouse to colonize the strains of each plant for subsequent research.Compared with the number of flowering leaves of wild type plants,the SlCDF3 overexpressing lines increased by 2.83,4.17 and 2.83 leaves respectively under SD conditions;SlCDF3overexpressing lines increased by 1.67,3.17 and 2.17 leaves respectively under LD conditions.The number of leaves required for overexpression of SlCDF1,SlCDF2,SlCDF4and SlCDF5 plants was not significantly different from that of wild type plants.4.Flowering-related FT-like genes are key genes for photoperiod control of the flowering pathway.There are three FT-like genes in tomato that are regulated by photoperiod and photoquality,namely SlSP5G,SlSP5G2 and SlSP5G3.Compared with wild-type plants,the expression of SlSP5G in S1CDF3 overexpressing plants increased significantly under LD treatment,and the expression of SlSP5G2 and SlSP5G3 increased significantly under SD treatment.In this study,we found that SlCDF3 as a regulator of FT-like genes was the main reason for the difference of flowering time in different light environments,and it provided a theoretical basis for the precise regulation of tomato flowering by light environment.