A Preliminary Study Of The Transcription Factors, Which Regulates MeAP2Gene In Cassava Under Drought Stress

Drought is a long-standing problems of the world, it affects the growth and physiological processes at all stages of the plant. Cassava （Manihot esculenta Crantz） is an important food crop in the tropics, in order to adapt to drought, salinity, temperature, diseases and other adverse environments, in the long-term evolution of the formation of a complex, high resilience to stress response mechanism, in which the transcription factor is a very critical factor, it is through the promoter cis-acting elements or with other transcription factors interacting functional areas, activating RNA enzyme, which initiates the transcription complex transcriptional expression of specific genes, and finally make the appropriate adjustment to Stress. The AP2/EREBP transcription factors that involved in plant growth and development, stress responses, hormone responses, morphogenesis, and other physiological and biochemical reactions. Therefore, this study selected and cassava drought-related MeAP2transcription factor genes, study their expression patterns under drought stress by RT-PCR, and explore the yeast one-hybrid transcription factor regulating MeAP2Screening gene transcription factor, and AP2gene regulation in relation to drought stress.Specific findings are as follows:1. Screened by RT-PCR from9MeAP2the two genes associated with drought resistance MeAP2, and its expression pattern consistent with the results of previous microarray gene done by analysis, AP2family members were induced under drought stress which, after the drought has the highest expression of the mid whose expression patterns are not identical, and there is a certain correlation between increased levels of expression made in the early response to drought stress, but over a period of time to express MeAP2-l and MeAP2-2and decreased expression of the two genes in response to different speeds and expression of drought, compared to the next two genes, either normal conditions or drought stress, MeAP2-2gene expression levels are higher than MeAP2-1gene, which is consistent with the results of microarray hybridization done before gene.2. Select MeAP2-2gene for subsequent yeast one-hybrid experiments, such as the use of web analytics JGI cloned into the MeAP2-2promoter sequence. This sequence contains a TATA-box, enhanced several typical eukaryotic promoter elements CAAT-box and GATA-box, etc. promoter basic components. Meanwhile there ABRE, MYCCONSENSUSAT, MYCATERD1, TC-rich repeats and other cis-acting elements associated with drought, as well as regulatory elements zinc finger protein DOFCOREZM.3. The results of the analysis of cis-acting elements, select enriched promoter region （-401bp to-685bp） drought, dehydration, and a variety of drought-related hormone cis-acting elements at the same direction as the tandem repeat3times bait vector construct the target sequence, we screened a cDNA library from cassava to several target sequences can be combined with the bait carrier cDNA by yeast one-hybrid system. In which, with the GJI database sequences than after cassava, and cassava4.1₀19320of Metallothionein protein homology is94.3%, this clone was named MeMT; cassava4.1₀19893of Core histone protein with homology is99.7%, this clone was named MeH; and cassava4.1₀18848of Heavy-metal-associated protein, atoxl-related homology is84.2%, this clone was named MeHMA. Metabolic pathways involved in the initial screening study of this research on cassava leaves drought stress mechanism is important, but also for the future of cassava research provided the basis for the molecular mechanism of drought.4. validated by quantitative PCR, these three genes and MeAP2-2gene in cassava leaves, petioles, from the area, the roots were expressed, and are under drought stress induced expression of drought stress to make the initial expression levels increased response, but over a period of time after the amount has decreased expression, and the expression in the arid4d reached a peak, consistent with MeAP2-2expression under drought gradient mode. Metabolic pathways involved in the initial screening study of this research on cassava leaves drought stress mechanism is important, but also for the future of cassava research provided the basis for the molecular mechanism of drought.