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Suppression of Bipolaris spp. by the saprophytic fungus Cladosporium pseudocladosporioides

Ashish Adhikari: Department of Plant Pathology, University of Florida

<div><em>Bipolaris</em> species are important plant pathogens that cause leaf spots, blight, crown rot and melting out diseases of primarily grass hosts. <em>Cladosporium</em> is a fungal genus which has a primarily saprophytic lifestyle, but some species have been reported to have antagonistic effects to biotrophic fungi, including rust pathogens. Recently, we co-isolated <em>Bipolaris</em> and <em>Cladosporium</em> from necrotic lesions on native and invasive understory grasses in Indiana forests. Initial observations suggested that the <em>Cladosporium</em> isolates were parasitic to <em>Bipolaris</em> conidia and appeared to reduce the likelihood of successful <em>Bipolaris</em> isolation. Multi-locus sequencing identified <em>Cladiosporium</em> isolates as <em>C. pseudocladosporioides</em>. We examined the antagonistic effect of <em>C. pseudocladosporioides </em>on <em>Bipolaris</em> in media assays. Hyphae of <em>C. pseudocladosporioides</em> were able to invade and outcompete <em>Bipolaris</em> colonies. We characterized the interaction between these fungi using light microscopy to look for evidence of pathogenesis. We propose that <em>C.</em> <em>pseudocladospoiroides</em> may mediate the interaction between <em>Bipolaris </em>pathogens and grass hosts.</div>