Multilocus analysis reveals phylogenetic placement of novel ERI fungi within Magnaporthaceae and Phaeosphaeriaceae of Ascomycota
P. L. VINES (1), M. Tomaso-Peterson (1), T. W. Allen (2), F. Hoffmann (1). (1) Mississippi State Univ, Mississippi State, MS, U.S.A.; (2) Delta Research and Extension Center, Stoneville, MS, U.S.A.
Ultradwarf bermudagrasses, in the low latitudinal region of the United States, often exhibit symptoms of decline during late summer and early fall months. Root systems appear diminutive, brittle, and discolored and are frequently colonized with dark, runner hyphae that are characteristic of ectotrophic root-infecting (ERI) fungi. Currently, spring dead spot (<i>Ophiosphaerella </i>spp.) and bermudagrass decline (<i>Gaeumannomyces graminis </i>var. <i>graminis</i>) are the only recognized diseases of ultradwarf bermudagrasses caused by ERI fungi. Observations from this study led to the theory that additional ERI fungi are accountable for compromised ultradwarf bermudagrass roots. Due to laborious and inconclusive identification efforts associated with traditional diagnostic techniques, molecular-based strategies were employed to test the hypothesis. Multilocus sequence analysis was performed on representative Mississippi State University (MSU)-ERI isolates and related taxa. Phylograms were erected using combined consensuses from maximum parsimony, maximum likelihood, and Bayesian inference analyses. These assessments indicate that MSU-ERI isolates share common ancestry with the known ultradwarf bermudagrass pathogens, <i>Gaeumannomyces graminis </i>var. <i>graminis</i> and <i>Ophiosphaerella </i>spp. In addition, evolutionary analyses define relatedness between MSU-ERI isolates and <i>Magnaporthiopsis</i> spp., indicating the discovery of novel fungi associated with decline of ultradwarf bermudagrasses.
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