Functional Analysis Of The Gene Involved In The Regulation Of Cold/Drought Stress Responses In Arabidopsis

Low temperature and drought stresses are the important environmental factors affecting plant growth and development,which is also one of the main factors leading to a decrese in the yield of crops in agriculture.To improve the tolerance of crops to abiotic tresses using transgenic techniques is very important for academic and economic significance.However,the key of this work is to clone the key genes inolved in the abiotic stress responses in plants and to understand their underlying mechanisms.With the completion of the Arabidopsis genome and the release of gene expression microarray analysis data,reverse genetics has become an important tool for understanding gene function.Expression of the LWT2 gene encoding an unkown protein was found to be induced by low temperature anddrought stresses.However,it is unclear whether the LWT2 gene plays important roles in the regulation of the responses of Arabidopsis plants to low temperature and drought stresses.To elucidate the function of the LWT2 gene,one T-DNA insertion loss-of-function mutant lwt2-1 was obtained from the Arabidopsis Biological Resource Center.In this study,the responses of the lwt2-1 mutant to low temperature and drought stresses were investigated.The main results are as follows:1.Under different low temperature stresses,survival rates of the lwt2-1 mutant plants were higher than those of the wild type,and the electrolyte leakage of the lwt2-1 mutant was lower than the wild type,suggesting that the injury of the lwt2-1 mutant to low temperature stress in cellular level is lower than to the wild type,and that the lwt2-1 mutant is more resistant to low temperature stress than the wild type.2.Analysis of gene expression revealed that enhanced resistance of the lwt2-1 mutant to low temperature stress was related to increased expression levels of CBF1 and CBF genes and their targeting genes,suggesting that the LWT2 gene might regulate the low temperature stress response by modulating a CBF1 /CBF3-mediated signaling transduction pathway.3.Under different drought stresses,survival rates of the lwt2-1 mutant plants were significantly higher than those of the wild type,and the lwt2-1 mutant was more resistant to the osmotic stress,indicating that the lwt2-1 mutant is resistant to drought stress.4.Analysis of gene expression showed that the enhanced tolerance of the lwt2-1 mutant to drought Stress was related to enhanced expression levels of the genes related with drought stress,suggesting that the LWT2 gene might regulate the drought stress response by modulating a CBF1/CBF3-mediated signaling transduction pathway.5.There were no siginificant differences in the accumulation levels of total soluble sugars and praline beween the wild type and the lwt2-1 mutant under cold and drought stresses,suggesting that enhanced resistance of the lwt2-1 mutant to low temperature and drought stresses might not related to the accumulation of total soluble sugars and praline.6.Genetic analysis and complementation experiment confirmed that the recessive loss-of-function mutation of LWT2 was the cause of the low temperature/drought stress-resistant phenotype.Taken together,all these results suggest the LWT2 gene plays important roles in the regulation of low temperature and drought stress responses.