Haplotype variation and phylogeography of Rhizoctonia solani AG1-IA strains based on rDNA5.8S-ITS and beta -actin gene sequence analyses.

摘要

The haplotype variation and phylogeography of Rhizoctonia solani AG1-IA strains were estimated using rDNA5.8S-ITS and beta -actin gene sequences. Two haplotypes of ITS sequences were revealed, designated as ITSa and ITSb. Thirty-four SNPs from the beta -actin gene, which displayed more allele discriminations than rDNA-ITS, were identified. The SNPs were used to classify R. solani into 12 haplotypes, designated as H1-H12. Most SNPs occurred at the third codon position and resulted as silent mutations. Three SNPs occurred at the first codon position and one SNP occurred at the second position, which these four SNPs causing non-synonymous mutations. According to the translational amino acid sequences, the 12 nucleotide-inferred haplotypes were further classified into 5 groups, designated as ITRL, VARI, VARL, VTRI, and VAMI. Analysis of the geographical distribution of 12 haplotypes, showed that H1 and H9 were widely distributed in all studied locations and existed simultaneously in the strains collected in most areas. The results lead to the speculation that H1 and H9 could be the founder haplotypes of beta -actin gene, and other haplotypes might be derived from them.