Whole-Genome Resequencing Reveals Significant Genetic Differentiation Between Populations from Maize and Sorghum and Candidate Effector Genes Related to Host Specificity.

is a devastating fungal pathogen that infects both maize and sorghum, leading to severe leaf diseases of the two crops. According to host specificity, pathogenic isolates of are divided into two formae speciales, namely f. sp. and f. sp. . To date, the molecular mechanism underlying the host specificity of is marginally known. In this study, the whole genomes of 60 isolates collected from both maize and sorghum were resequenced, which enabled identification of 233,022 single-nucleotide polymorphisms (SNPs) in total. Phylogenetic analysis indicated that all isolates are clustered into four genetic groups that have a close relationship with host source. This observation is validated by the result of principal component analysis. Analysis of population structure revealed that there is obvious genetic differentiation between two populations from maize and sorghum. Further analysis showed that 5,431 SNPs, including 612 nonsynonymous SNPs, are completely co-segregated with the host source. These nonsynonymous SNPs are located in 539 genes, among which 18 genes are predicted to encode secretory proteins, including six putative effector genes named , , , , , and . Sequence polymorphism analysis revealed various numbers of SNPs in the coding regions of these genes. These findings provide new insights into the molecular basis of host specificity in .