Screening And Preliminary Analyzing Resistance Related Transcription Factors Of Wheat That Are Induced By Powdery Mildew

Wheat is one of the most important staple food crops of the world, feeding about 40% of the world population. However, wheat production and quality have been under threat from increasing powdery mildew. As an important kind of gene expression regulatory protein, transcription factor control gene expression level through interaction with specific sequences of promoter. Some transcription factors play an important role of regulation the expression of defense response genes. Therefore, analysis expression profile of transcription factor in wheat respond to powdery mildew disease-, has very important scientific value and practical significance, this contribute new knowledge to our understanding of the molecular mechanism of wheat-powdery mildew pathosystem.Some MYB and bZIP transcription factors in plants have been evidenced to play important roles in regulating defense response to various pathogens. Our intention is to identify defense-related MYB and bZIP transcription factor genes using the following strategy:By searching the full-length cDNA libraries constructed by Doctor Zhao Guang Yao and the wheat EST databases of NCBI and TIGR, we get 10 cDNA sequences. Using BLASTX and DNAMAN, we predicted protein sequences, scaned those sequences on PROS1TE and Pfam, and analized the structure of protein sequences. This experiment investigated gene expression patterns of 4 MYB and 6 bZIP transcription factor genes within 24 hours induced by the powdery mildew by using real-time qPCR. The main results are as follows:1,Predicting the protein structure through PROS1TE and Pfam database, the results are as follows:(a)Four proteins belong to MYB transcription factor. TaMYB23 and TaMYBpd2 belong to R2R3-MYB subgroup with R2 and R3 repeat fragments, TaMYBpd6 belongs to R1R2R3-MYB subgroup, TaMYB107 has MYB-like domain. In addition, TaMYB23 has a nuclear localization signal (10-38) and a transcriptional activation domain (390-400)at the upstream and downstream of protein sequence respectively; upstream of TaMYBpd6 has a transcriptional activation domain at the position of 22-31, and a nuclear localization signal at the position of 458-469 in protein sequence.(b)Six proteins belong to bZIP transcription factor. Besides TabZIP73 the other five members also have some other structural domain:G-box binding protein MFMR had been predicted in the protein structures of TabZIP15 and TabZIPpd16, G-box binding protein MFMR in the protein structure of TabZIPpd16 is rich of pralines, the content is 15.2%. Different transcriptional activation features are found in TabZIP57, TabZIP15 and TabZIPpdl7; however, TabZIP73, TabZIPpdlO and TabZIPpdl6 have no typical transcriptional activation domain; One nuclear localization signal is found in TabZIPpd10.2,Real-time qPCR made the following results:(a) After inoculation of powdery mildew fungus, transcripts of TaMYBpd6, TaMYB23, TaMYBpd2, TaMYB107, TabZIP15, TabZIP57and TabZIPpd17 increasingly accumulated both in resistant and susceptible materials whthin 24 hours. However, expression characterization of TabZIP15 and TabZIPpd17 is consistent between disease-resistant and susceptible materials, without obvious difference, so these 3 genes may be not related to disease resistance; the expression of TaMYB107 in susceptible materials is higher than that of resistant ones, and may be related to disease susceptibility. But TaMYBpd2 could expressed continuously after induced by powdery mildew, gene expression level in disease-resistant materials is significantly higher than that of susceptible ones; Expression of TaMYBpd6 is restrained in normal growth condition, but is activated after induced by powdery mildew; Expression of TaMYB23 is earlier in disease-resistant materials than in susceptible after inoculation powdery mildew, which may have interactions with Pm13 and TaMYB23. Expression level of TabZIP57 in disease-resistant materials is 2 times of that in the other contrast ones. Therefore, TaMYBpd2, TaMYBpd6, TaMYB23 and TabZIP57may be related to disease resistance.(b) TabZIPpdl6 and TabZIP73 were induced to express only in resistant materials, not in susceptible ones. However, the expression of TabZIP73 is earlier when inoculation than no inoculation in resistant materials, and the expression in susceptible materials is higher than that of resistant ones. So expression characterization of TabZIP73 is much complex and need further study. Expression of TabZIPpdl 6 showed obvious difference between disease-resistant and susceptible materials, and may be related to disease resistance.(c) The expression of TabZIPpd10 has no obvious differences in different treatments and materials, which could be constitutive expression, but the expression in resistant materials is higher than that of susceptible ones, even if not induce expression, TabZIPpd10 may be related to disease resistance. Expression of TabZIP57 is restrained both in resistant and in susceptible materials inoculated, it may be down-regulated expression, and be not related to disease resistance.