High Genetic Diversity and Obvious Population Differentiation of Exserohilum turcicum from Maize in China Revealed by SSR Markers

Exserohilum turcicum is the causal agent of northern corn leaf blight, an important disease of maize in China. To investigate the genetic diversity and population structure of this pathogen, 90 isolates from three provinces in China were analyzed using simple sequence repeat markers. Nei’s gene diversity values across the three geographical populations ranged from 0.439 to 0.536, with a mean of 0.499. Phylogenetic analysis indicated that all isolates were clustered into five genetic groups, each predominantly associated with a specific geographic population. Population structure analysis revealed that the dominant genetic clusters was obviously different in the three populations. Molecular variance analysis demonstrated that 21.57% and 78.43% of the total variation were distributed among and within the three populations, respectively. Fixation indices between the three populations varied from 0.081 to 0.165, with an average of 0.134. These findings reveal high genetic diversity and obvious population differentiation of E. turcicum from maize in China.