The Role Of OfSVP Transcription Factors And Dilated Proteins In Osmanthus Fragrans Flowering

Osmanthus fragrans has a special flowering process and mechanism,flower transformation,flower bud differentiation and flower opening are regulated by environmental temperature.The relative low temperature of environment can significantly promote the flower bud differentiation process of Osmanthus fragrans,but also regulate the flower opening process.The effects of different temperature treatments(25 ?and 19 ?)on flower bud differentiation of Osmanthus fragrans ‘Yan Hong' were observed.Seven SVP genes were cloned and the expression patterns of these 7 SVP genes and their four downstream genes in flower bud differentiation were analyzed.To explore the mechanism of relative low temperature affecting flower bud differentiation and the role of SVP gene,and to analyze the functions and functions of three extender genes OfEXPLA1,OfEXPA2 and OfEXPA4 in order to clarify their role in the regulation of flower opening at relative low temperature.The main findings are as follows:1.The effect of relative low temperature on flower bud differentiation: in different temperature treatments(25 ?and 19 ?),the relative low temperature treatment(19 ?)could make Osmanthus fragrans ‘Yan Hong' advance into flower bud differentiation and accelerate the whole flower bud differentiation process.One of the most significant effects of relative low temperature is inflorescence differentiation and pistil differentiation,inflorescence differentiation shortened by 18 days and pistil differentiation shortened by 26 days.2.OfSVP gene and analysis of its expression pattern: seven SVP genes were cloned from Osmanthus fragrans,and four genes(OfSVP1,OfSVP3,OfSVP4,OfSVP5)were found to have complete cDNA sequences by ORF finder on-line analysis.There were deletions at the 5 'end of OfSVP2,OfSVP6 and OfSVP7 genes.The amino acid sequences of 7 SVP genes were compared and analyzed.OfSVPs had the main conserved characteristics of SVP,including MADS-box,K-box and I-box motifs at N-terminal and non-conserved C-terminal,Phylogenetic tree analysis showed that 7 OfSVP genes belonged to two subfamilies respectively.Quantitative fluorescence analysis of seven SVP genes and four other downstream SVP genes showed that OfSVP 4/6/7 in relatively low temperature during flower bud differentiation,the expression of OfSVP1 was up-regulated,the expression of OfSVP2/3/5 did not differ significantly at different temperatures.The expression levels of FT,SOC1 and GA20ox2 at 19 ? were higher than those at 25 ?,which was negatively correlated with the expression of OfSVP4/6/7.Explain the possibilities that OfSVP4/6/7 could promote flower bud differentiation in response to low temperature treatment,which might affect the flower bud differentiation process by regulating the expression of FT,SOC1 and GA20ox2.3.Functional analysis of OfEXPLA1,OfEXPA2 and OfEXPA4: three recombinant plant expression vectors of 35S::OfEXPLA1-GFP,35S::OfEXPA2-GFP and 35S::OfEXPA4-GFP were constructed and then transferred into onion epidermis cells.It was found that the green fluorescent signals of OfEXPLA1,OfEXPA2 and OfEXPA4 proteins were located on the cell wall.Arabidopsis lines transformed with OfEXP gene promoter of Osmanthus fragrans were obtained by improved inflorescence infection method,and the phenotypes of Arabidopsis thaliana lines were observed.It was found that the average leaf length and width of the three transgenic lines were longer than those of wild type lines.The average inflorescence length of OfEXPLA1 and OfEXPA4 promoter transgenic Arabidopsis thaliana lines was longer than that of wild type,and the average length of inflorescence of Arabidopsis thaliana line with OfEXPA4 promoter was significantly longer than that of wild type.The number of inflorescences was also more than that of wild type.there was no significant difference in inflorescence length and number between OfEXPA2 promoter transgenic arabidopsis and wild type lines.