Promoter Function Analysis Of An Abiotic-Stress Tolerance TaFRA Gene Cluster

The response of plants to stress is very complex, and it involves a series of signal transductions and a large number of genes. As a cis-acting element, promoter plays an important role in the specific spatial and temporal expression. So, studying on the driving activity of promoter is essential for stress tolerance breeding.In previous studies, a new gene related to abiotic stress was cloned and identified, which is named TaFRA (F-box Protein Related to Abiotic stress). Three copies tandemly existed in wheat and high similarities were found among them, but their promoters were different more. So in order to understand the genes function and differentiation, three promoters (Pro_TaFRAl, Pro_TaFRA2 and Pro_TaFRA3) of the TaFRA gene were isolated and fused to vector with the GUS as reporter, and were introduced into rice mediated by Agrobacterium, respectively. In addition, the most difference between the promoters of TaFRA2 and TaFRA3 is a MITE inserted in TaFRA2’s promoter, so Pro-DEL-MITE (MITE deleted from TaFRA2) and GUS fusion vector was also introduced into rice to analyze the effection of MITE to promoter activity. Several positive rice lines with three promoter and GUS were obtained. In the present study, both histochemical staining of GUS and Real-time PCR were used to analyze the three promoters’tissue speciality, and discover different expression patterns under abiotic stress, including low temperature, NaCl, PEG and ABA treatments. The ultimate goal is to understand the division of labor for the gene cluster members through the methods of histochemical staining of GUS and Real-time PCR. The major progresses were as follows:1) Under the normal growing conditions, Pro TaFRA1 can’t drive GUS gene expression in root but expressed in leaf in each stage, i.e. tillering stage, flowering stage, filling stage and maturing stage, and also the mature seed. Comparing with the other two promoters, in the plants with Pro_TaFRA1, the relative expression level of GUS varied more largerly under low temperature, PEG and ABA treatments. Under low temperature and NaC1 treatments, the induction activity of Pro_TaFRA1 is relatively slow.2) Under the normal growing conditions, Pro_TaFRA2 can drive GUS gene expression in all organs except root in different growth periods. And it plays a complementary role relative to the other two promoters. Under the abiotic stress conditions, the change range of relative expression of GUS drived by Pro_TaFRA2 is small, and it presents early expression.3) Under the normal growing conditions, Pro_TaFRA3 has the characteristic of constitutive promoter, its tissue specificity isn’t obvious and the expression of quantity during different periods is various. Under abiotic stress, the change of relative expression keeps a higher level, and its relative expression of quantity could arrive to the maximum rapidly. Pro_TaFRA3 is obviously an early expression promoter.4) Whether under the normal growing conditions or abiotic stress, Pro_Del-MITE still has the ability to drive the GUS gene express, but its GUS staining activity level was much lower than that with the Pro_TaFRA2 containing the MITE sequence. It can be concluded that the MITE insertion plays an important role in enhancing the promoter’s activity.