Phylogenetic Analysis Of SET Domain-containing Proteins And Functional Study Of Rice SDG736

Histone lysine methylation plays an important role in epigenetic regulation.The SET(Su(var)3-9,Enhancer-of-zeste and Trithorax)domain,an evolutionarily conserved motif,approximately contains 130?150 amino acids that form a knot-like structure and constitute the enzyme catalyticsite for histone lysine methylation which wide range regulate growth and development processes in plant.There have been many reports on the histone lysine methyltransferase in animals,but most of the reports related to model plant Arabidopsis thaliana in plants.In this study,14 representative species from lower to higher plants were selected for phylogenetic analysis of SET domain families.According to the results of phylogenetic analysis and the expression profiles of rice KMT3 subfamily members under stress conditions,SDG736 gene was selected as the research object.SDG736 overexpression vector,knockout vector,fluorescence location vector and interference vector were constructed for genetic transformation.The results are as follows:1.591 sequences of SET domain proteins were identified from 14 representative species in plant kingdom.Phylogenetic results showed that the SET domain family could be divided into eight subfamilies——KMT1,KMT2,KMT3,KMT6 A,KMT6B,KMT7,RMT and S-ET.2.KMT3 subfamily may be involved in flowering regulation or flower development through H3K4/36 histone methylation activity.Moreover,the expression profile of rice KMT3 subfamily show that the expression of SDG736,a homologous gene of Arabidopsis thaliana SDG4 in rice,increased significantly under high temperature and drought stress3.Construction of SDG736-related vectors to transform Arabidopsis thaliana and rice.The results showed that the overexpression of SDG736 could promote Arabidopsis flowering.The expression analysis for Arabidopsis gene involved in flowering pathway by real-time PCR showed that FLC gene expression decreased while SCO1 gene expression increased compared with wild-type Arabidopsis.4.Under drought stress,the expression of ABA1,ABA2 and ABA3 gene,functioning in first step of the biosynthesis of the abiotic stress hormone abscisic acid(ABA),showed remarkably elevated expression in SDG736 overexpression Arabidopsis thaliana.5.Obtained SDG736 overexpression transgenic rice and SDG4 RNAi and CRISPR/Cas9 knockout Arabidopsis,constructed RFP-SDG736 fluorescent expression fusion vector;Laying the foundation for further research the functions of SDG736.