Abstract

In this study, the genetic diversity and structure of 90 monosporidia mating-type isolates of Sporisorium scitamineum collected from China were comprehensively evaluated based on the DNA extracted from mating-type haploid sporidias using inter-simple sequence repeat (ISSR) polymorphism molecular marker technique. Fifteen selected ISSR primers produced 162 amplified DNA fragments, of which 115 (71.0%) were polymorphic. Polymorphic information content (PIC) values ranged from 0.12 to 0.92 with an average of 0.82, indicating that a moderate degree of genetic diversity exists among these 90 monosporidia mating-type isolates of S. scitamineum collected from China. Genetic differentiation coefficient (G_st) was calculated to be 0.320, indicating that the total genetic variation between populations was 32%, while 68% of the total genetic variation was from within populations. Meanwhile, gene flow (N_m) was 1.063, indicating lower rate of gene flow between populations. Based on the ISSR marker data set, the results of clustering by the unweighted pair group method of arithmetic average and principal component analysis were similar and could divide these 90 S. scitamineum isolates into two main groups. The isolates collected from the same province tend to cluster in the same main groups. This study shows that the genetic differentiation of these 90 monosporidia mating-type isolates of S. scitamineum was highly correlated with the ecological environment of collection sites, and the heterogeneity of ecological environment was the main driving force for the differentiation of S. scitamineum.

Key words: Sugarcane, Sporisorium scitamineum, mating-type haploid sporidia, inter-simple sequence repeat, genetic diversity.