Characterization of Exserohilum isolates associated with northern corn leaf blight in Brazil

The control of corn diseases, such as leaf blights caused by fungi of the genus Exserohilum, has been the object of much research. Studies on the genetic diversity and pathogenicity of isolates are essential for developing more effective control strategies. This study aimed to identify and characterize Exserohilum isolates associated with leaf blight in corn fields in different regions of Brazil and evaluate the pathogenicity of these isolates. Symptomatic corn leaves were collected from different regions of Brazil. The fungi were isolated in the PDA medium, and the colonies were morphologically characterized. The DNA of the isolates was extracted and used to sequence the ITS and GAPDH regions. The obtained sequences were used for phylogenetic analysis from sequences of 27 other isolates already sequenced and registered in a molecular database. The pathogenicity of isolates representing each region was tested in the popcorn line susceptible to leaf blight (L55). Nine Exserohilum isolates were collected in three regions of Brazil. The phylogenetic analysis allowed the identification of two Exserohilum species: eight E. turcicum and one E. rostratum i. The lesions caused by E. rostratum were shorter in length and had a lighter colour compared to those caused by E. turcicum on the leaves. The five tested isolates showed high pathogenicity when inoculated into the susceptible popcorn line.