Identification and Genetic Diversity of Formae Speciales of Setosphaeria turcica in China.

Setosphaeria turcica is an important pathogen that causes northern leaf blight of corn and sorghum. In total, 188 isolates were isolated from diseased leaves of maize and sorghum in China. However, differences in morphology were not apparent among S. turcica isolates derived from different hosts. The formae speciales were identified as S. turcica. f. sp. zeae and S. turcica. f. sp. sorghi. Universally primed polymerase chain reaction (UP-PCR) analysis led to the conclusion that genetic differences were present among these formae speciales and divided these isolates into five clades. The isolates of each clade belonged to the same forma specialis, and different formae speciales were assigned to different clades. The results of the present study demonstrated that pathogenic specialization of the S. turcica isolate correlated more closely with genetic diversity than geographical distribution. Therefore, combined with assays for pathogenicity, UP-PCR analysis yields an enhanced understanding of the formae speciales of S. turcica.