Study On Vegetative Compatibility Groups Of Curvularia Lunata

Curvularia lunata was considered as prevalent pathogens to cause corn Curvularia leaf spot disease. Now the disease can damage crops significantly and is becoming an increasingly major threat.Vegetative compatibility groups (VCGs) of 70 strains of C. lunata isolated from infected corn leaves collected from 39 different regions covering 11 provinces in China were assessed through complementation tests of nitrate-nonutilizing (nit) mutants. The objectives of this study were detection and diversity degree of vegetative compatibilitygroups in C. lunata population.5 strains were used from 70 tested strains of C. lunata to screen the more suitable media which generated nit mutants. These strains were cultured on water agar chlorate medium (WAC), potato sucrose agar medium (KPS), minimal medium amended with 0.16% L-asparagine(MMC), Czapek medium amended with 0.05% sodium nitrite (KNI), Czapek medium amended with 0.16% L-asparagine (KAS) (all containing 2.5% KClO₃), respectively. Colony growth of C. lunata was more restricted on WAC medium than other media. WAC medium was benefit to bring chlorate-resistant mutants. Strains which were induced on WAC and identified on Czapek or minimal medium (MM) can get four phenotypes of nit mutants which were nit1, NitM, nit3 and nitD. nit 1 and nit3 were primary. Strains induced on WAC and identified on Czapek-Dox agar medium (CDA) can generated three phenotypes of nit mutants which were nit 1,NitM,and nit3. nit1 and NitM were primary. The percentage of NitM mutants obtained from CDA was higher than that of other two medium. The results showed that combination of WAC and CDA medium was more effective for recovery of nit mutants of C. lunata.70 Strains induced on WAC and identified on CDA got 10,197 chlorate-resistant mutants. Of them, 2,207 nit mutants (21.64% of all tested chlorate-resistant mutants) were screened onto CDA. These nit mutants were divided into three phenotypes by their growth response to nitrate, nitrite, and hypoxanthine as the nitrogen sources. Among the nit mutants, 63.30% were characterized as nitl, 33.26% as NitM, and 3.44% as nit3. At least two nit phenotypes mutants were screened from each of the 70 tested strains, and 52 strains...