Expression And Function Analysis Of Transcription Factors In Rice Under Abiotic Stress

Plant growth and product are always affected by various abiotic stresses, functional analysis of stress responsive gene will benefit for molecular dissection of regulatory mechanisms in plants in response to abitotic stress. bHLH transcription factor (TF) is one of the largest TF families in plants, which plays an important role in eukaryotes growth and development. Lots of bHLH TFs have been studied in animals, however, few of these TF genes were functionally dissected in plants. In the present study, two functional candidate genes OsbHLH59, OsbHLH63were selected from the results of genome-wide gene expression of drought tolerance. And these two genes were transformed into Nipponbare, the transgenic plants were evaluated for salt tolerance by morphological and phenotypical traits measurement, their molecular mechanisms of salt tolerance were further dissected. Meanwhile, a set of MYB TF genes were profiled in two rice genotypes with contrasting chilling tolerance by using quantitative real time PCR analysis, results will provide a basis for further analyzing the function of MYB TFs in abiotic stress tolerance.1. Firstly, the expression patterns of OsbHLH59and OsbHLH63in different varieties with diverse abiotic stress tolerance. Result indicated that two genes were repressed in leaves, but induced in roots of salt tolerance line177-103under salt stress, and the expression of OsbHLH63was more affected by salt stress than that of OsbHLH59. However, OsbHLH59and OsbHLH63were evidently down-regulated in both LTH and IR29under chilling stress condition, and the repressed expression of OsbHLH63in LTH only was reverted on recovery. These results implied that the genes OsbHLH59and OsbHLH63were involved in salt and chilling stress response.2. The candidate genes OsbHLH59, OsbHLH63over-expressed in Nippobare, and their expression patterns were further profiled in T2transgenic line under salt stress treatment. Results showed that only the transgenic plant H29with over-expressed OsbHLH63was more salt tolerant than the control, especially with strong recovery tolerance. The content of Proline in Transgenic plant of OsbHLH63was significant higher than that of the control under salt stress, indicated that over-expression of OsbHLH63resulted in accumulation of praline and then enhanced salt tolerance.3.The quantitative real-time PCR was used to profile the MYB transcription factors under chilling stress in two rice genotypes of LTH and IR29with contrasting chilling tolerance. Results showed that most of the MYB genes were differentially regulated under low temperature, and a set of MYB genes were specifically regulated in LTH. A portion of MYB genes have the same change tendency in both varieties with diverse expression level under stress. All these results showed that differentially regulated MYB genes might be related to the genotype-specific chilling stress tolerance, and presented data will provide a basis for further functional dissection of chilling tolerance MYB genes in rice.