Characteristic And Promoter Analysis Of A Drought Related R2R3-MYB Transcription Factor MeMYB63in Cassava(Manihot Esculenta Crantz)

Cassava (Manihot esculenta Crantz) is a tropical crop, with a typical high photosynthetic capacity and has a unique adaptation mechanism for tropical intermittent drought. Drought, as one of the important abiotic stress factor, can affect the growth of crop and limits crop production. Under the condition of drought stress, plants can regulate the expression of related genes through to start a series of physiological and biochemical reaction against drought environment. In the study of Arabidopsis, rice and corn and other plants, MYB transcription factor is a super family, whose members have played a fundamental role in the regulation of metabolism and secondary metabolism, cell differentiation, developmental processes and stress response process (Gao et al.2011; Wang et al.2002; Rabinowicz et al.1999), and MYBR2R3transcription factor is likely take part in a wide range of response to stress process of plants. Therefore, study of cassava MYB transcription factor is not only to resolve the molecular mechanism of high-yielding when cassava under drought, but also has very important implication for drought-resistant varieties of cassava breeding.The cassava genome sequencing has been completed, which provides a great convenience research for cassava gene function and regulation of express. By transcriptome sequencing and semi-quantitative RT-PCR analysis, We found several MYB genes in cassava has obvious response to drought stress, for example, MeMYB63genes in this thesis studies is one of them. In drought stress treatment for14days of cassava leaf and petiole, expression level of MeMYB63gene decreased obviously. In order to research the expression of the gene under drought stress condition, we have separated the promoter region of cassava MeMYB63gene1500bp DNA upstream from the start codon, and found it contains ABRE, WRKY, I-BOX, T-BOX, MYB, MYC and some other important cis-acting element. We use the GUS gene to report the expression of MeMYB63in transgenic Arabidopsis to analyze the activity of promoter, and found it was expressed in leaves and root of transgenic Aarabidopsis seedlings.Full-length of MeMYB63genome is753bp, which has three exons and two introns. The MeMYB63protein contains two conserved MYB DNA binding domain (MYB DNA Binding Domain, BD), it is belong to R2R3MYB proteins. We use green fluorescent protein (green fluorescent protein, GFP) as a marker gene to marker MeMYB63gene by construct vector and transfer it into tobacco by Agrobacterium-mediated transient transformation system to analyzed the subcellular localization of gene product expression, and the result shows that the fusion protein of MeMYB63with GFP only appears in the nucleus. In addition, the yeast transcriptional activation experiment has revealed that MeMYB63gene has transcriptional activation function, indicating that the gene has transcriptional activation domain (Activation domain, AD).In this paper the experimental results show that the cassava MeMYB63gene is an R2R3MYB transcription factors, in the leaf of cassava it has obvious response to drought stress signal, it was expressed in both leaves and root of transgenic Aarabidopsis.It provides an important foundation for future studies of function and regulation under the condition of drought stress about this gene.