| Based on the results of random amplified polymorphism DNA (RAPD) ,20 polymorphic DNA primers out of 120 arbitrary decamer primers were used for RAPD assay of mating type of Setospaeria turcica. 10 Isolates were evidently seperated into 2 RAPD groups (RGs) based on mating type. The experimental results showed there were higher correlation between the mating type based on RAPD analysis and the RAPD analysis could be as a new and exact identifying method for mating type of Setospaeria turcica .Furthermore, 26 reproducible polymorphic DNA primers were used for RAPD assay of physiological races of Setospaeria turcica. The results showed that genegic similarity coefficiences of 20 isolates used varied from 0.4762 to 0.8856. Among them,higher homogeneity and lower difference existed between the isolates belonging to race 0 and that belonging to race 1. Based on the amplification results, the 20 isolates used were clustered into 2 RAPD groups (RGs).Group RG1, included 5 isolates of race 0 and 4 isolates of race 1. Group RG2, included 1 isolate of race 1 and the other 10 isolates belonging to race 13, 3, IN, 12, 3N, 23 and 2N, respectively. The results indicated that race 0 was genetically similar to racel and greater divergence of other races. Further analysis revealed that RAPD sub-groups were (RSGs) related to the geographic regions to a certain extent.The optimal RAPD reaction system was established. In the total volume of 25uL, there were 2.0U Taq DNA polymerase, 2.0mM Mg2+, 200uMdNTP, 30ng arbitrary primer, luL l0XPCRbuffer and 30ng template DNA. Amplification was performed by the following program:3 minutes at 94,40 cycles of Iminute at 94, Iminute at 37 , 2minutes at 72, and a final extention of 6minutes at 72 .The mating type of 37 isolates of Setospaeria turcica collected from Hebei LiaoningN Heilongjiang provinces and so on in 2001 was examined in Sach medium. The experimental results indicated that three kinds of mating type were found. 24 isolates were mating type A and their frequency was 64.9%. 10 isolates were mating type a and the frequency was 27.0%. 2 isolates were examined to be compatible with both matingtype A and a, which was named as mating type Aa. Mating type Aa of Setosphaeria turcica is first reported.Perfect stage of Setosphaeria turcica indicated that temperature was a key and the optiomal condition was 25, pH=7.0 and with light.There were no significant differences between mating type A and a in infection efficiency, lesion size, sporulation and fitness index, but they were distinctly different in latent period.Crude toxin of mating type A and a was analyzed with High Performance Capillary Elecrophoresis (HPCE) technique. There were great diversities in spectrum between them, the similar spectrum existed in the same mating type. Moving time of the two spectrum belonging to the two mating types was significantly different. It was possible that they were special spectrum of the mating type A and mating type a, respectively. HPCE was probable an assistant method for identifying mating type.The physiological race of Setosphaeria turcica was identified among 37 isolates collected from different areas of China in 2001 on com which contained different resistant genes. The results showed that there existed both race 0 and race 1, besides, race 12, 23, 3N, 12N, 123N were also found among 37 isolates used. Race 123N which should be taken us into account was pathogenic to corn with any kind of resistant gene.
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