Submitted to: Mycologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/24/2012
Publication Date: 10/25/2012
Citation: Crouch, J., Tomaso-Peterson, M. 2012. Anthracnose disease of centipedegrass turf caused by Colletotrichum eremochloae, a new fungal species closely related to Colletotrichum sublineola. Mycologia. 104(5):1085-1096. Interpretive Summary: Each year fungi cause billions of dollars damage to agricultural crops and natural resources in the United States. Anthracnose diseases including those that attack lawn grasses are caused by a group of fungi with many different species. In this research it was shown that an anthracnose disease of centipede grass in the southern United States is caused by a previously undescribed fungus in that species complex. Sequences of DNA from recently collected specimens were compared with those obtained from old specimens back to 1916. These specimens were identified as a different fungus that is now known to occur only on cultivated sorghum and Johnson grass. The sequences from the old and recent centipede grass pathogen were shown to be alike. This suggests that the fungus on centipede grass was introduced from China with its host many years ago. The new fungal species and the lookalike species are both described and illustrated. This research will be used by plant pathologists and lawn grass breeders to identify this fungal pathogen and to breed lawn grass that is resistant to this disease.
Technical Abstract: Colletotrichum is a cosmopolitan anamorphic fungal genus responsible for anthracnose disease in hundreds of plant species worldwide, including members of the grass family Poaceae. Anthracnose disease of the widely planted, non-native, warm-season lawn grass, Eremochloa ophiuroides (centipedegrass), is commonly encountered in the southern United States, but the causal agent has never been identified. In this study, we use DNA sequence data from modern cultures and archival fungarium specimens to determine the identity of the fungus responsible for centipedegrass anthracnose disease, and provide experimental confirmation of pathogenicity. C. eremochloa sp. nov., a pathogen of centipedegrass, is proposed based on phylogenetic evidence from four sequence markers (Apn2, Mat1, Sod2 and ITS). C. eremochloa isolates from centipedegrass shared common morphology and phenotype with C. sublineola, a destructive pathogen of cultivated sorghum and johnsongrass (Sorghum vulgare, S. halepense). Molecular phylogenetic analysis identified C. eremochloa and C. sublineola as closely related sister taxa, but genealogical concordance supported the distinction of the two organisms as unique phylogenetic species. Fixed nucleotide differences between C. eremochloa and C. sublineola were observed from collections of these fungi spanning 105 years, including the 1904 lectotype specimen of C. sublineola. C. eremochloa was identified from a fungarium specimen of centipedegrass intercepted at the U.S. ports from a 1923 Chinese shipment; the multilocus sequence type of this specimen was identical to modern samples of the fungus. Thus, it appears that the fungus likely migrated to the U.S. not long after centipedegrass was first introduced to the U.S. in 1916 from China, where the grass is indigenous. C. eremochloa is described, and a new description of C. sublineola from the lectotype and proposed epitype are provided.