Sooty leaf spot-a new fungal disease of sorghum caused by Paraphaeosphaeria sorghi sp. nov

A leaf spot disease-herein named sooty leaf spot of sorghum (Sorghum bicolor)-was observed in Vicosa, Minas Gerais, Brazil. A pycnidial fungus producing fuliginous conidial masses was regularly found associated with sooty spots on leaf blades and sheaths. The fungus was isolated in pure culture from specimens collected at two localities. The examination of morphological features combined with molecular analysis of the internal transcribed spacer (ITS) region of rDNA, large subunit ribosomal ribonucleic acid (LSU rDNA) and beta-tubulin region (BenA) clearly demonstrated that the two isolates were grouped in a single clade, separate from other Paraphaeosphaeria species, a new taxon. Inoculations of both isolates of the new species on maize, sugarcane and sorghum plants led to disease development only on sorghum; therefore, Koch's postulates were fulfilled for this fungus-host association. Here, we describe the new species Paraphaeosphaeria sorghi sp. nov. as a novel fungus causing leaf spot of S. bicolor in Brazil and worldwide and represent an addition to the long list of fungal diseases of sorghum.