The Genes Expression Profile and Functional Analysis of Rice Transcription Factor OsbHLH061 and OsbHLH068 under Abiotic Stresses
Date Issued
2012
Date
2012
Author(s)
Chen, Yi-Jen
Abstract
Abiotic stresses such as drought, cold, heat, salt, have adverse effects on plant growth and crop yields. Transcription factors (TFs) are important for control the expression of target genes in response to abiotic stresses. The Apetala2/Ethylene Responsive Factor (AP2/ERF) and basic Helix-Loop-Helix (bHLH) are superfamily of TFs that regulate diverse processes of plant development and stress responses. However, the importance of specific AP2/ERF and bHLH TFs that are involved in the regulation of plant abiotic stress tolerance is still not known. In this study, we identified 4 putative stress-related TFs OsERF106, OsbHLH035, OsbHLH061 and OsbHLH068 by bioinformatics and gene expression patterns analysis. We used functional genomics approach to understand their roles under abiotic stresses, especially take advantage of rice Tos17 and corresponding Arabidopsis T-DNA mutants. We obtained the homozygous rice and Arabidopsis mutants for 4 TF genes by molecular characterization, including PCR-genotyping and RT-PCR analysis. The results showed that OsbHLH061 gene Tos17 rice mutant have low germination vigor. The Tos17 mutant of OsbHLH061 gene was much sensitive to drought, salt and heat stresses. In addition, AtbHLH047 T-DNA mutant line from Arabidopsis with corresponding homolog of OsbHLH061 gene, was sensitive to salt and mannitol stresses during seed germination, but opposite to seedling growth and aldult plants. Then, we heterologouly expressed OsbHLH061 gene in Arabidopsis. When compared to wild type plants, the transgenic plants exhibited short root length under salt stress. These results suggest that OsbHLH061 gene function may be similar to AtbHLH047 and it is worthy to apply complementary rescue approaches to further confirm OsbHLH061 genes function. OsbHLH068 gene Tos17 rice mutant showed low germination vigor. The Tos17 mutant of OsbHLH068 gene was sensitive to drought, salt stresses. In addition, AtbHLH112 T-DNA mutant line from Arabidopsis with corresponding homolog of OsbHLH068 gene, was sensitive to salt and mannitol stresses during seed germination, but opposite to seedling growth and aldult plants too. The heterologous expression and complementary rescue was carried out by overexpression OsbHLH061 gene in Arabidopsis wild type and mutant line. When compared to wild type plants and mutant line showed that the transgenic plants exhibited long root length under salt stress, because OsbHLH068 has low gene expression level. Taken together, the above study indicates that OsbHLH061 and OsbHLH068 TFs play significant roles in rice abiotic stress response. In the future, we will analyze the downstream stress-responsive genes under abiotic stress conditions to understand their genes regulatory network. In this study, we established a basis of these rice TFs candidate genes cloning and analyz their gene regulatory mechanism under abiotic stresses. It can be expected that genetic engineering TFs targeted gene transformation would provide a potential application in crop tolerance improvement.
Subjects
abiotic stress
rice Tos17 mutant line
Arabidopsis T-DNA mutant line
Type
thesis
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