The Sensitivity Of Population Of Blumeria Graminis F.sp．tritici Isolates To Temperature In 2009 And Cloning And Analysis Of The Sequence Of HSP Gene

The sensitivity of 129 isolates of wheat powdery mildew (Blumeria graminis f.sp.tritici) sampled from 7 sites was tested by detached leaf segment method. The results revealed that the mean ET50 of all isolates tested was 22.72℃. The highest and the lowest ET50 of isolates were 24.48℃and 19.88℃respectively. ET50 values of 41.09% isolates were between 23℃and 24℃which represented nearly half of the isolates.There were a certain difference for isolates sensitivity to temperature among different provinces or cites, and there was a significant negative correlation between the sensitivity of pathogen population and the longitude or latitude. The results showed that the mean value of the termination threshold of 129 isolates tested was 26.65℃, also the latent period of the isolates which were relatively not sensitive to temperature was shorter at higher temperature, and the disease severity was higher. The verification of frequency distribution of the isolates with different sensitivity to temperatures has revealed that the pathogen population in natural environment has been effected by the selection pressure of temperature.We extracted RNA of wheat powdery mildew with high sensitivity, medium sensitivity and low sensitivity to temperature using Trizol reagent and reversely transcribe RNA to cDNA by the Reverse Transcription Kit of invitrogen, then amplified cDNA by a pair of degenerate primers to obtain its core sequence.A pair of gene specific primers GSP1and GSP2 were designed by the core sequence. The 3'and 5'terminal sequence of cDNA were cloned by the RACE technology and analysed by the DNAStar software. We extracted DNA of wheat powdery mildew with three sorts of sensitivity to temperature, and amplifed the full length of core region of DNA using three pairs of specific primers designed according to the full length of cDNA.lastly. According to the result of sequencing we deduced the sequence of HSP gene.The result showed that the size of cloned full length cDNA of HSP gene of wheat powdery mildew was about 2600bp The ORF of the cDNA lay between 35th and 1400th nucleus acid. The full length of ORF was about 1365bp,encoding 455 amino acid and the length of non-encoding regions of both ends was 35bp and 1061bp The size of full length of partial DNA core region was about 350bp.With the Blast of HSP70 gene of parital fungus,we concluded that the sequence of HSP70 gene of wheat powdery mildew with three sorts of sensitivity to temperature had the closest genetic relationship with Podospora Anserina,but had a farther genetic relationship with Aspergillus oryzae,Trichophyton rubrum and Neosartorya fischeri. The result will lay basis for furtherly comparing the mechanism of adaptability of different kinds of wheat powdery mildew to temperature.