The Function Analysis Of MYB2、MYB7、MYB8 Gene And The Clone Of WRKY Gene In Scutellaria Baicalensis

Abiotic stress, such as sality, drought, and extreme temperatures, adversely affects growth and productivity, and triggers morphological, and molecular changes in plants. MYB proteins have been proved to be involved in many significant physiological and biochemical processes, such as regulation of primary and secondary metabolism, flavonoid biosynthesis, response to various biotic and abiotic stresses, hormone synthesis and signal transduction. Much less is known about the functions of R2R3-MYB proteins in Scutellaria baicalensis Georgi under the abiotic stress conditions. To study the molecular mechanism by which MYB2,MYB7 and MYB8 respond to abiotic stress in Scutellaria baicalensis Georgi, we analyzed the phenylpropanoid content, growth phenotype, antioxidant enzyme activity and expression of flavonoids synthesis associated genes in Sb MYB2,Sb MYB7 and Sb MYB8-overexpressing transgenic tobacco plants after Na Cl,mannitol and abscisic acid(ABA) treatment.The main results in this paper are as follows:(1): Compared with WT tobacco, the lutin in overexpression of Sb MYB2 transgenic tobacco was markedly increased, the Kaempferol3-rutinoside-7-glucoside in overexpression of Sb MYB7 transgenic tobacco was notably increased; the chlorogenic acid was increased both in overexpression of Sb MYB2 or Sb MYB7 transgenic tobacco. The caffeoylquinic acid dimer and caffeoylquinic acid in overexpression of Sb MYB8 transgenic tobacco was dramatically increased. These results indicted that Sb MYB2、Sb MYB7、Sb MYB7 all involed in the metabolic pathway of flavonoids.(2) In order to identify the function of Sb MYB2, Sb MYB7, Sb MYB8 in abiotic stress, the overexpressing-Sb MYB2, Sb MYB7, Sb MYB8 transgenic tobacco were obtained. The results showed that the root length, fresh weight and the activity of antiactivity enzymes were all notably increased, indicted that Sb MYB2, Sb MYB7,Sb MYB8 could increased the resistance of drought, high sality and exogenous hormone.(3) The genes that related with the metabolic pathway of flavonoids were rapid induced in overexpression of Sb MYB2, Sb MYB7, Sb MYB8 transgenic tobacco.(4) Sb MYB8 could specific binding with Gm MYB92 BS3 that located in the promoter of Sb CHS.(5) 33 Sb WRKY transcription factors were obtained in transcriptome of Scutellaria baicalensis. The characterization of nucleic acid and they encoded proteins were analysed.(6) After treated with GA3, the expression level of Sb WRKY1 、 Sb WRKY2 、Sb WRKY6、 Sb WRKY10 、 Sb WRKY11、 Sb WRKY12 、 Sb WRKY13、 Sb WRKY15 、Sb WRKY17、Sb WRKY18、Sb WRKY19、Sb WRKY20、Sb WRKY21、Sb WRKY22、Sb WRKY25、Sb WRKY28、Sb WRKY29、Sb WRKY30、Sb WRKY32、Sb WRKY33 were all increased, whrease the Sb WRKY16 was increased after 1 h and 2 h treatment, the Sb WRKY24 and Sb WRKY27 were increased after 1 h treatment. These results suggested that Sb WRKY may responsed to the GA3 signal and regulated the dowmstream genes. We choosed the Sb WRKY33 which was closely related with the genes that metabolic pathway of flavonoids for futher study.(7) The result of subcellar localization confirmed that Sb WRKY33 was in nucleus.