Expression And Function Analysis Of Vegetable Soybean Transcription Factor Gene GmMYB103

MYB transcription factor was confirmed to have widely participate in the regulation of flavonoid biosynthetic genes, expression of the MYB family genes in plants could be induced by a variety of stress conditions, and its play an important role in regulating the metabolic pathways of the plant isoflavones. To define its status and role in the metabolism of flavonoids in soybean, MYB transcription factor GmMYB103was cloned and transformed to soybean cotyledons to clarify its function. The results will help to reveal the regulation mechanism of soybean isoflavones.In this thesis, PCR was used to clone GmMYB103, which is one of the MYB transformation factor genes.On the basis of the preliminary studies, the nucleic acid sequence, structural characteristics and the expression characteristics of the encoded protein were further analyzed and identified. The over-expression of the target gene GmMYB103was further carried out in soybean cotyledon to identify the biological role of GmMYB103in regulation the synthesis of isoflavones. Transgenic hairy toot was induced after infection the soy bean cotyledons with agrobacterium rhizogenes and the expression and function of the specific genes GmMYB103in transgenenic hairy root were preliminary discussed. The main conclusions are as follows:1. GmMYB103gene was cloned by RT-PCR. An849bp open reading frame (ORF) was found to encode a protein with282amino acids, which contains two SANT binding domain (of MYB domain). GmMYB103MYB binding domains, located at the10-62and63-117amino acids, respectively. Phylogenetic trees were constructed using protein sequence analysis. The results showed that protein encoded by G?nMYB103. LjMYB103, LjMYB101and GmMYB101was closely classified and form a branch. The closest relationship and the high homology of the encoded proteins, suggested that GmMYB103may have a similar biological functions with these genes.2. GmMYB103gene expression was carried out in soybean tissues using semi-quantitative RT-PCR method. The results showed that GmMYB103was highly expressed in flowers, moderate expr in leaves at the early and middle stage, and also expressed in the stem at the lateral stage, but very low expression in leaf at the lateral stage.3. The biosynthesis of isoflavoid was restrained by over expression of GmMYB103. Semi-quantitative RT-PCR and quantitative PCR analysis were used to analysis the function of GmMYB103gene. The results indicated that over expression of GmMYB103gene restrained the key genes in phenylalanine pathway, such as CHS,4CL and CHR. However the expression of PAL, C4H, IFS and CHI did not change significantly. Soybean isoflavones content was determined by UV spectrophotometer. The result showed that overexpression of GmMYB103significantly reduced the isoflavones content in soybean root.