| Wheat(Triticum aestivum) stripe rust (Puccinia striiformis f. sp. Tritic) is an air-spreading virus in the world. It is a major threat to the wheat (Triticum aestivum)in China, especially in the south-west part of the country where the wheather condition is suitable for the breeding of the virus. Therefore, in order to protect wheat production, to study the effect of Puccinia to the wheat at physiology level as well as the interact between the virus and host and how the plant defeat this particular disease at molecular level is quite important for breeding new cultivated varieties which has long-term resistance to Puccinia.Two wheat lines, L693and L661, were chosen for this research. The effects of stripe rust on both lines’photosynthesis and fluorescence dynamics were compared, and the result showed that L693was more effective in net photosynthetic rate than L661through all the development stages after the tassel period. The photosynthetic rate of L661decreased dramatically in later period, while L693kept a relatively high rate. The same trend was found in stomatal conductance in later period. The same conclusion could be draw from chlorophyl fluorescence dynamics research, as L693showed a higher photosynthetic rate after the dip-dye. These results illustrated the L693had a potential resistance to stripe rust while L661did not. Therefore, it is a scientific and reasonable method to choose these two lines as matierials to build the SSH-cDNA libaraty of stripe rust.In order to research the molecular mechanism of stripe rust resistance as well as search the resistance gene and new molecular mark in wheat, an SSH cDNA libaraty was built through suppression subtractive hybridization technology. In the experiment, L693(the resistance line) was set as tester while L661(the susceptible line) the driver.112EST were obtained and then undertook a homology sequence alignment.28of them were found relating to photosynthesis. After electronic position and cloning,76of them were identified as multicopy genes,34were single copy genes or homology multicopy genes, and2with no homology sequence.The pair of primers to amplify the whole sequence was designed based on the draft genome sequence of Chinese spring from IWGSC, which was homologous with the band of resistance characteristics. After a successful amplification of the full-length sequence, the result showed that it contained an integrated promoter, five exons and a PlyA structure. The P value of the gene prediction of the four exons was up to0.999, which indicated a high probability that the sequence contains a gene structure. Afterwards, the teritiary structure of this sequence was predicted using the SWISS-MODEL online homology modeling. The predicted structure showed it contains two βαββαβ domains and LHC**C conserved regions at both βa conjuction, which has the ability of combinig heavy metals(such as Cu2+,Zn2+,Ag+). So far, the homology sequences of this target gene were found in XYZ, however, no research has been done to its function. This study has sucessfully cloned a potential Puccinia resistance gene which could possibly be a heavy-metal-binding protein. As no such protein has been found in earlier researches on the cloning of wheat resistance genes, this result need further study. |
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