Fifty-five representative samples of Rhizoctonia solani isolates, which were collected and isolated from five different ecological regions in Sichuan Province, China, were purified and analyzed for the pathogenicity a...Fifty-five representative samples of Rhizoctonia solani isolates, which were collected and isolated from five different ecological regions in Sichuan Province, China, were purified and analyzed for the pathogenicity and molecular genetic variation. The hyphal fusion test revealed that almost all the isolates belonged to the AG-IIA group except the isolate D42. In addition, some of the isolates were ＇bridging isolates＇, which could fuse with several groups simultaneously. The pathogenicity analysis on in vitro leaves confirmed a significant pathogenicity variation in the tested isolates. The 55 isolates were then classified into 8 groups by further RAPD （randomly amplified polymorphic DNA） cluster analysis at the similarity coefficient of 0.941. The results suggest that under the certain ecological conditions in Sichuan Province, China, most of the R. solanistrains were genetically stable, but a few changed drastically.展开更多
The aims of this study are to determine the population genetic structure of Rhizoctonia solani,associated with potato,and to assess its resistance degree to pencycuron and thiabendazole fungicides.A total of 57 strain...The aims of this study are to determine the population genetic structure of Rhizoctonia solani,associated with potato,and to assess its resistance degree to pencycuron and thiabendazole fungicides.A total of 57 strains of R.Solani were isolated from different potato crop fields in Mexico,and were classified according to their anastomosis group(AG)using the polymerase chain reaction(PCR)and restriction fragment length polymorphism(RFLP)-based analysis.Then,the amplified fragments were digested with four different endonucleases(Mse I,Ava II,Mun I and Hinc II).The Repetitive Element Sequence-Based PCR(rep-PCR)technique was used to determine the genetic diversity in R.solani populations.Results obtained by PCR-RFLP showed that 81%of the isolates were identified as belonging to AG-3 group,14%to AG1-1B and 5%to AG-11 group.In response to fungicides inhibition,IC_(50)between 0.014-0.039 mg a.i./L for pencycuron,and 0.82 to 2.91 for thiabendazole were determined,This IC_(50)value showed that the resistance factor(RF)values ranged from 1.4 to 3.945 and 0.27 to 0.97,respectively;this tendency suggests that isolates are susceptible to thiabendazole.The AG groups showed a heterogeneous resistance to pencycuron and thiabendazole,being more tolerant to these fungicides AG1-1B and AG-11 groups.The genetic analysis shows a low genetic diversity among(P-value 0.3225)and within(P-value 0.3275)populations;this can indicate a clonal reproduction and little parasexual cycle among the analyzed isolations.展开更多
基金the National High- tech Research and Development Program of China (Grant No. 2003AA212030)the Foundation for Doctorial Research in the Southwest University of Science and Technology (Grant No. 07ZX0101)the Program for Changjiang Scholars and Innovative Research Team in University of China (PCSIRT)(Grant No. IRT0453)
文摘Fifty-five representative samples of Rhizoctonia solani isolates, which were collected and isolated from five different ecological regions in Sichuan Province, China, were purified and analyzed for the pathogenicity and molecular genetic variation. The hyphal fusion test revealed that almost all the isolates belonged to the AG-IIA group except the isolate D42. In addition, some of the isolates were ＇bridging isolates＇, which could fuse with several groups simultaneously. The pathogenicity analysis on in vitro leaves confirmed a significant pathogenicity variation in the tested isolates. The 55 isolates were then classified into 8 groups by further RAPD （randomly amplified polymorphic DNA） cluster analysis at the similarity coefficient of 0.941. The results suggest that under the certain ecological conditions in Sichuan Province, China, most of the R. solanistrains were genetically stable, but a few changed drastically.
文摘The aims of this study are to determine the population genetic structure of Rhizoctonia solani,associated with potato,and to assess its resistance degree to pencycuron and thiabendazole fungicides.A total of 57 strains of R.Solani were isolated from different potato crop fields in Mexico,and were classified according to their anastomosis group(AG)using the polymerase chain reaction(PCR)and restriction fragment length polymorphism(RFLP)-based analysis.Then,the amplified fragments were digested with four different endonucleases(Mse I,Ava II,Mun I and Hinc II).The Repetitive Element Sequence-Based PCR(rep-PCR)technique was used to determine the genetic diversity in R.solani populations.Results obtained by PCR-RFLP showed that 81%of the isolates were identified as belonging to AG-3 group,14%to AG1-1B and 5%to AG-11 group.In response to fungicides inhibition,IC_(50)between 0.014-0.039 mg a.i./L for pencycuron,and 0.82 to 2.91 for thiabendazole were determined,This IC_(50)value showed that the resistance factor(RF)values ranged from 1.4 to 3.945 and 0.27 to 0.97,respectively;this tendency suggests that isolates are susceptible to thiabendazole.The AG groups showed a heterogeneous resistance to pencycuron and thiabendazole,being more tolerant to these fungicides AG1-1B and AG-11 groups.The genetic analysis shows a low genetic diversity among(P-value 0.3225)and within(P-value 0.3275)populations;this can indicate a clonal reproduction and little parasexual cycle among the analyzed isolations.
