A New Species of Fungus Symbiotic with the Morning Glory Ipomoea tricolor

Presenter/Authors(s)

Corinne Hazel, Daniel Panaccione

Abstract or Description

Ergot alkaloids are toxic chemicals produced exclusively by fungi and are important for their use in pharmaceuticals and their impacts on livestock. Ipomoea tricolor is a common plant species in the family Convolvulaceae (morning glory). Limited sequence data and HPLC analysis of ergot alkaloid presence in plant tissues show evidence of a fungal symbiont of I. tricolor despite no identified or externally visible fungus. Our goal is to isolate and describe this fungus. Observation of fungal hyphae on evacuated seed coats from I. tricolor and subsequent transfer onto malt extract agar resulted in cultures of the symbiont isolated from the plant. The fungus grew slowly as white hyphae and sometimes aggregated into synnema-like structures, both structures lacking any spores. Sequences of PCR products from this culture were most similar to the preliminary sequence data available for the symbiont. Using PCR and enzymatic digests, the same fungus was detected in I. tricolor hypocotyls and lower portions of the stem but not in roots, cotyledons, or leaves. Phylogenetic analyses of PCR products from fungal cultures indicated that the symbiont of I. tricolor was distinct from, but related to, the two described species of Periglandula previously observed in other species of morning glories. Based on these data and observations, we conclude that the symbiotic fungus of I. tricolor is a distinct species of Periglandula and propose the name Periglandula clandestina.