| Two isolates belonging to opposite mating type, 01-12 and 01-15, were selected as parent isolates to induce ascospore production of Setosphaeria turcica, and 79 single ascospores were isolated. 79 crossing progenies belonging to which mating type were identified by sexual cross with parental isolates. 36 isolates belonged to 'a' mating type, and were the same as parent isolate 01-12, and 20 isolates belonged to 'A' mating type and were the same as parent isolate 01-15. But the ratio of two mating type deviated 1:1 apparently, as deduced that the mating character was decided by polygene site. Otherwise, 3 isolates were bisexual and 20 isolates were neuter.The experimental results had found that new isolates collected had greater mating ability than those isolates which subcultured for 3 years. In the favorite conditions that the quantity of FeCl3 was 0.02 mg per 1000 mL medium, the number of mature ascospores and the stability of asci occurrence were greatly increased. A simplified method for isolating monosacospores was also set up in this test.Progenies of 36 ascospores selected were used to study the genetic diversity of parent isolates and sexual crossing progenies of S. turcicum based on RAPD analysis. The results indicated that there were evident variation on genetic map between parent isolates and progenies isolates. There were total of 144 RAPD markers with 21 arbitrary primers, and 126 markers presented the diversity and the percentage was 87.5%. The similarity coefficient of diferrent strains was 0.6450~0.7914. Moreover, there were no definite rules as to whether markers in progenies were more similar to parents by similarity analysis, even though that within parents were more similar than between parent and progeny. It showed that the genetics of Setosphaeria turcica were very complex. Parent isolate 01-12 maybe had stonger genetic ability than parent isolate 01-15 in the course of sexual cross.The stabilized RAPD reaction system was established in this paper. In 25 Lreactions, there were 1 units of Taq DNA polymerase, 200 M of mixed dNTP, 2.5 L of 10 PCR buffer, 0.8 M of arbitrary primer and 50ng of genomic DNA, the rest volume filled with aseptic ddH2O. Amplification was performed by the following program: initial denaturation at 95 for 3 min followed by 40 cycles of denaturation at 94 for 1 min, annealing at 45 for 50 sec, extension at 72 for 2 min, and final extension at 72 for 5 min, kept at 4 at last.There were great diversity in the esterase isozyme map among parent isolates and progenies. The specific band in Rf=0.042 location was a distinctive marker for parents. A progeny occurred apparent mutation.Mycelia of S. turcica could be used to prepare the protoplast. The yield of protoplasts was significantly correlated with enzymes, osmotic stabilizer, temperature and treating time. The proper condition shown in this paper was that the ground mycelium of S. turcica was treated by mixed enzymes (10 mg/mL Cellulase and 10 mg/mL Snailase) for 72 hours at 28癈 after shocking cultrued in PD medium for 4 days, and the mixed enzymes had a better effect when they were dissolved with 0.8 mol / L mannitol osmotic stabilizer.
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