Genetic diversity and population structure of Rhizoctonia solani AG-1 IA, the causal agent of rice sheath blight, in South China

AbstractThe genetic diversity and population structure among 72 rice-infecting isolates of Rhizoctonia solani AG-1 IA, collected from 12 counties (subpopulations) of Guangdong, Guangxi and Hainan provinces (populations) in south China, were investigated using nine inter-simple sequence repeat (ISSR) markers. A total of 116 bands were amplified, with a majority of amplified fragments ranging from 500 bp to 2500 bp in size, of which 110 (94.8%) were polymorphic. Seventy-two isolates were grouped into six major clusters at 73% genetic similarity coefficient by the unweighted pair group method with arithmetic mean (UPGMA) with Dice’s distance matrices. The genetic diversity was high [percentage of polymorphic bands (P %) = 94.83%; Shannon’s diversity index (I) = 0.3175; Nei’s diversity (h) = 0.2034] at the population level, but low within populations [P % = 53.38%; Shannon’s diversity index (I) = 0.2734; Nei’s diversity (h) = 0.1811]. The mean coefficient of gene differentiation (Gst) was 0.165, indicating th...