Anastomosis Group Identification Of Rhizoctonia Isolates From Turfgrass In Several Areas Of China And Screening Of Antagonistic Trichoderma Strains

Turfgrasses are more and more impotant in the urban afforestation, and now the disease of turfgrasses caused by Rhizoctonia spp is a common and important disease. In this study, we indentified the anastomosis group obtained from turfgrass in Qingdao, Taian, Dongying of Shandong Province, Shanghai and Guangzhou of Guangdong Province. Also we selected a high efficient antagonistic Trichoderma isolate to the the major anastomosis group of turfgrass Rhizoctonia. The results gained are summarized as following :1.Fourty-eight isolates were obtained from turfgrasses in several areas of China (including Qingdao, Taian, Dongying, Shanghai and Guangzhou). Anastomosis group indentification showed that the isolates belonged to multinucleat Rhizoctonia WAG-Z,AG1-IA,AG4-HG-I and binucleate Rhizoctonia AG-A,AG-P,AG-L.Of these, WAG-Z was the major anastomosis group(70.83% of total isolates),AG-A was the second anastomosis group ( 14.59% of total isolates) , AG1-IA was the third(8.34% of total isolates), there were all one strain of AG4-HG-I,AG-P and AG-L(2.08% of total isolates). AG-P,AG-L and AG-A were isolated for the first time from turfgrass in China.2.Putting the mycelium on the slide after DAPI, obsorbed under the microscope. The results showed that there were multinucleate and binucleate of the nucleus of the mycelium cell of Rhizoctonia from turfgrass. There were 5-11 nucleus of AG1-IA and 3-10 nucleus of AG4-HG-I. The nucleus of WAG-Z were complex, and the main was multinucleat Rhizoctonia. AG-P, AG-L and AG-A were binucleate Rhizoctonia.3.Phylogenetic analysis among isolates belonging to different AGs was studied based upon 5.8S rDNA-ITS sequences. The results obtained from nuclear and mitochondrial sequence analyses were similar. The sequence alignment of 5.8S rDNA-ITS revealed that the isolates of the same AGs had a high sequence similarity.The isolates of the different AGs had a low sequence similarity. So using 5.8sDNA-ITS sequence analysis was a effective method of the AGs identification.4.There were 8 biocontrol characters of 10 Trichoderma isolates (including growth, inhibitionrate, amount of sporulation, tolerate to low temperature, tolerate to high temperature, tolerate to acid, tolerate to alkaline and Tolerate to Carbendazim).They were evaluated and analyzed by Grey related degree.The results showed that the biggest Grey related degree was T05-037, the second one was T05-066 and the third was T05-048. The biocontrol characters of these three isolates were approximative to the reference. T05-037 was the best among these isolates.5.Using morphology analysis, we identified that isolate T05-037 that we selected in this study was Trichoderma viride. We studied the inhibition percentage of T05-037 to different anastomosis group by cultivated on the plate. The results showed that the isolate T05-037 is effectivity to the 4 isolates that belonged to different anastomosis group.The inhibitionrate to WAG-Z is the biggest. So we can conclude that T05-037 is potential to prevente the disease of turfgrass caused by Rhizoctonia spp.