Cloning Of Two Histone Methyltransferase Genes From Wheat And Their Functional Analysis

The fowering time of wheat directly affected the final grain yield and quality,and the investigation of molecular mechanisms involved in flowering regulation is greatly important for molecular breading focused on the high yield and quality in wheat.During the process of flowering initiation,histone modification mediated gene regulation plays an important role.Based on our previous research,two histone methyltransferase genes were cloned,and their sequence characteristics,as well as their functions of flowering regulation were analysed.The main research results are summarized as follows:1.Two EST sequences of wheat,corresponding to the At SDG7 and At SDG8 respectively,were obtained by Blastx analysis in wheat EST database using two Arabidopsis histone methyltransferase genes SDG7 and SDG8.Based on the sequence analysis,the c DNA fragments of these two wheat SDG genes were cloned from wheat by RT-PCR method.2.Two genes Ta SDG7 and Ta SDG8 encoding wheat histone methyltransferases were cloned by RACE and bioinformatics methods.Each of the cloned sequences includes a complete CDS encoding histone methltransferase with a typical SET conserved domain.According to the aligments,5 and 11 gene members of Ta SDG7 and Ta SDG8,respectively,were cloned.3.Three plant expression vectors of Ta SDG8-1,Ta SDG8-2 and Ta SDG8-8 were constructed and introduced into the Arabidopsis mutant sdg8 by Agrobacteriummediated transformation.The flowering time phenotyping of T1 transgenic plants indicated that all of these 3 Ta SDG8 members have certain regulatory functions of flowering regulation,the regulatory effect of Ta SDG8-1 is the most significant and its overexpressing in mutant sdg8 lead to a complete complementation and demonstrated normal flowering time.The complementary effects of Ta SDG8-3 is weaker than that of Ta SDG8-1 and stronger than Ta SDG8-8.It seems that sequence differences among Ta SDG8 gene members were potentially related to their different flowering regulatory effects,which remains to be further confirmed.4.In order to systematiclly analyse the expression and regulation patterns of At SDG8,the promoter sequences of At SDG8 were cloned and transgenic T1 Arabidopsis plants were obtained,in which the reporter gene GUS was drove by the cloned promoter.The expression patterns of the reporter gene will be systematacially analysed in T2 generation.