Biologycal Characteristics And Genetic Diversity Of Pathogen From Wheat Sharp Eyespot And Corn Sheath Blight In HeBei Province

Wheat sharp eyespot and Corn sheath blight were one serious disease caused byRhizoctonia. This kind of disease was occurred often in the wheat and corn growing area inChina. Wheat sharp eyespot and Corn sheath blight was getting more severe in rescentyears in HeiBei province. The yield and quality of wheat and corn are decreased clearlydue to Rhizoctonia infection. Diseased samples were collected from ten counties or citiesin Hebei. The objective was to understand on the population structure and genetic diversityof the pathogen in Hebei. The results will set up a theory foundation for establishing theintegrated management measures of wheat sharp eyespot and corn sheath blight.1. One hundred and thirty isolates of wheat sharp eyespot and twenty-one isolates ofcorn sheath blight collected from Hebei province were identified with morphologicalcharacteristics. The result showed that the wheat sharp eyespot was caused by binuclearRhizoctonia and the corn sheath blight was caused by polynuclear Rhizoctonia in Hebeiprovince. The fittest pH is 6 of Rhizoctonia, and the growth of mycelial on PDA is thequickest, the second is on maize media, the last is on water-agar. Fe³⁺,Zn²⁺,Pb²⁺,Mg²⁺,Mn²⁺,Hg²⁺ have some certain influence on the growing of mycelial.2. All Rhizoctonia isolates from the samples of wheat sharp eyespot and corn sheathblight in Hebei were tested for anastomosis group. The result showed that pathogen ofwheat sharp eyespot belonged to anastomosis group CAG-1, AG2 and WAG, of themCAG-1 with frequency of 95.16% was major anastomosis group. The pathogen of cornsheath blight belonged to anastomosis group AG-1-IA, AG-1-IC, AG-2, AG-5 and CAG-1,in which AG-1-IA and AG-5 with frequency of 44.44% and 33.33% were majoranastomosis group.3. The pathogenicity of some typical isolates was valuated by artificialcross-inoculation. The results showed that the virulence of Rhizoctonia on original hostwas higher than on the other host, the virulence of anastomosis group CAG-1 of binuclearon wheat was higher than it on maize, the virulence of polynuclear on maize was higherthan it on wheat. The result also showed that the virulence of isolates from different areawas different, but there was no significant difference among the pathogenicity of isolates.4. An efficient AFLP DNA fingerprinting protocol for Rhizoctonia was modified. Theimprovement of protocol could facilitate the research on the genotyic diversity, constructing genetic maps of the pathogen.5. Thirty Rhizoctonia isolates of wheat sharp eyespot and twenty Rhizoctonia isolatesof corn sheath blight were amplified with three AFLP primer combinations. A tatal of 144AFLP bands were amplified of binuclear Rhizoctonia, and 105 were polymorphic bands.The rate of polymorphism bands was 72.91%. 150 DNA bands (fingerprints) wereobserved of polynuclear Rhizoctonia, and 145 out of 150 DNA bands were polymorphicones. The rate of polymorphism bands was 90.0%. The result based on the cluster analyseindicated that DNA polymorphism of Rhizoctonia was correlated with genetic variation ofanastomosis group. The DNA polymorphism was not correlated with geographical locationand the pathogenicity of the isolate.