Functional Study Of Rice Transcription Factor WRKY22 In Response To Aluminum Stress

Aluminum (AI) toxicity is one of the major limiting factor for crop growth on acid soils.Rice is considered the most tolerant to aluminum among cereal crops but the molecular and physiological mechanisim remains unclear.Here we selected a gene OsWRKY22 from the database of our Microarray,based on which this gene is up regulated under aluminum treatment. We analysised its expression pattern and found that it could fast respond to aluminum and its transcripts arrived at high level in 3 hours. Spatial expression analysis showed that the expression of OsWRKY22 is up regulated in the root tips but not in the basal root and shoot when exposed to aluminum. We further observed the phenotypes of OsWRKY22 T-DNA insertion mutants wrky22, and found that wrky22 were more sensitive to aluminum compared with the wild type, for the relative root enlongation of the mutant is shorter than that of the wild type. Evans Blue staining showed that the damage caused by aluminum was more serious than that of the wild type,which further proved the transcription factor OsWRKY22 participated in the rice aluminum stress response.Subcellular localization revealed that OsWRKY22 localized at the nucleus. Transcriptional activation analysis in yeast showed that OsWRKY22 had transcriptional activation potential. All of these experiments confirmed OsWRKY22 is a functional transcriptional factor.We also analysised the expression of OsWRKY22 in artl mutant and found that the aluminum induced expression is higher in the mutant so we speculated that OsWRKY22 is not regulated by ART1.We also constructed an overexpression vector of this gene for further research.In summary our results showed that OsWRKY22 involves in rice aliminum tolerance and that OsWRKY22 is a typical transcription factor but further study is needed to clarify the regulation mechanism which may help us understand the mechanism of rice aluminum tolerance better.