Isolation And Functional Analysis Of A Salt-stress Response Gene TaERF4of Wheat

Salt stress is widespread in the world and it has a serious impact on agricultural production. Saline soil accounts for2.1%of the total land area in China. Around10%of the cultivated land exists different degree of salinization phenomenon, and salinization phenomenon is still increasing. The salinization threatens China’s food production and food security.Common wheat is one of the most widely distributed and planted food crops in the world. Wheat is also one of the main food crops in China. In recent years with the rapid development of China’s economy, the rising of our living standard, the increasing demand for food, traditional breeding techniques can not satisfy people’s needs. The use of saline soil for agricultural production is helpful in solving these problems. The use of biological techniques to study the wheat’s genetic diversity of salt tolerance, to screen the salt stress response genes and to study genie function provide insights into molecular mechanisms of salt tolerance. These studies help to breed new varieties of salt resistance wheat so people can utilize saline soil more effectively to increase crop yield.A new variety Shanrong No.3has been generated in our lab via the somatic hybridization of common wheat Jinan177with Thinopyrum ponticum. Shanrong No.3had a significantly higher salt-resistance than its parent Jinan177. Cloning and analysising functions of Shanrong No.3wheat genes related to salt stress and drought stress, studying the molecular mechanism of salt tolerance, have important significance in breeding new varieties of food crops which can resist to salt or drought stress.In this study, we cloned TaERF4from the SR3cDNA library based on a screening of the expression patterns of SR3genes involved in the pathway during abiotic stress, and made a series of functional study. The full length of TaERF4cDNA is582bp. TaERF4encodes a protein of193amino acids with a typical AP2/EREBP conservative structure domain, an EAR motif and a nuclear localization signal sequence(NLS). EAR motif is essential for transcription repression(Ohta et al.,2001). The sub-cellular localization experimental results showed that the TaERF4protein was localized in the cell nucleus. RT-PCR analysis results indicated that TaERF4expression was up-regulated by the imposition of salinity in short time. With the gene transformed into yeast, the experimental results showed that the the protein products of TaERF4gene didn’t has activity of activating transcription in yeast expression system. It could be concluded that TaERF4protein was a transcription repressor. The over-expression of TaERF4in Arabidopsis increased sensitivity to salinity stress of the transgenic lines. But there was no obvious difference between the transgenic lines and the wild type Arabidopsis while they were treated with mannitol, ABA or H2O2. To further understand the the machanism of TαERF4, RT-PCR was performed to trace the expression of salt-responsive marker genes in the wildtype and TαERF4transgenic Arabidopsis. The results showed that the expression of AtNHX1, AtNHX2, AtRD29A in transgenic lines was significantly lower than the wild-type Arabidopsis. Relation between AtNHX1, AtNHX2and transportion of Na+had been found in previous studies. According to the experimental results, TaERF4might be involved in the ABA independent pathways of stress signal transduction.