Genetic diversity of rice Rhizoctonia strains in North Vietnam and Myanmar

抄録

Representative isolates of 25 Rhizoctonia solani AG1-IA, associated with rice sheath blight were examined for rep-PCR fingerprinting variations and sequence variations in the ITS-5.8S rDNA region in North Vietnam. Forty four isolates of R. solani, 30 isolates of R. oryzae and 29 isolates of R. oryzae-sativae were isolated from the diseased samples collected from three different regions of Myanmar. Assay of rep-PCR was subjected to the two primers evaluations, ERIC2 and BOXA1R, respectively. Moreover, sequences of these isolates were aligned with other known R. solani sequences from the NCBI and GenBank and distance and parsimony analysis were used to obtain population structures. Clonal population of R. solani AG-1 IA, causal agent of rice sheath blight, were presented at the two distinct groups (Rep-Vet1 and Rep-Vet2) based on the fingerprinting dendrogram with the similarity coefficient score at 75% differentiations. Geographical relationships of the clonal population such as the two distinct groups were not presented. However, these two subgroups including clonal populations of Rep-Vet1 and Rep-Vet2 were divided into different clade separated from known AG1-IA subgroups based on sequencing analysis. Vietnam AG1-IA Isolates collected from Red River Delta presented not correlation of geographical distribution but dispersals in the collection area by analyzing of their clonal population structures. Moreover, two types of R. solani AG1, two types of R. oryzae, and three types of R. oryzae-sativae of Myanmar isolates were differentiated by rep-PCR. The results obtained from rDNA-ITS sequence analysis also revealed the presence of genetically diverse populations of R. solani, R. oryzae and R. oryzae-sativae in Myanmar.