| Title: | Pseudoflowers produced by Fusarium xyrophilum on yellow-eyed grass (Xyris spp.) in Guyana: A novel floral mimicry system? |
| Author(s): | Laraba I; McCormick SP; Vaughan MM; Proctor RH; Busman M; Appell M; O'Donnell K; Felker FC; Catherine Aime M; Wurdack KJ; |
| Address: | "Mycotoxin Prevention and Applied Microbiology Research Unit, National Center for Agricultural Utilization Research, Agricultural Research Service, US Department of Agriculture, Peoria, IL 61604-3999, USA. Electronic address: imane.laraba@usda.gov. Mycotoxin Prevention and Applied Microbiology Research Unit, National Center for Agricultural Utilization Research, Agricultural Research Service, US Department of Agriculture, Peoria, IL 61604-3999, USA. Functional Food Research Unit, National Center for Agricultural Utilization Research, Agricultural Research Service, US Department of Agriculture, Peoria, IL 61604-3999, USA. Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907-2054, USA. Department of Botany, National Museum of Natural History, Smithsonian Institution, Washington, DC 20013-2012, USA" |
| DOI: | 10.1016/j.fgb.2020.103466 |
| ISSN/ISBN: | 1096-0937 (Electronic) 1087-1845 (Linking) |
| Abstract: | "Pseudoflower formation is arguably the rarest outcome of a plant-fungus interaction. Here we report on a novel putative floral mimicry system in which the pseudoflowers are composed entirely of fungal tissues in contrast to modified leaves documented in previous mimicry systems. Pseudoflowers on two perennial Xyris species (yellow-eyed grass, X. setigera and X. surinamensis) collected from savannas in Guyana were produced by Fusarium xyrophilum, a novel Fusarium species. These pseudoflowers mimic Xyris flowers in gross morphology and are ultraviolet reflective. Axenic cultures of F. xyrophilum produced two pigments that had fluorescence emission maxima in light ranges that trichromatic insects are sensitive to and volatiles known to attract insect pollinators. One of the volatiles emitted by F. xyrophilum cultures (i.e., 2-ethylhexanol) was also detected in the head space of X. laxifolia var. iridifolia flowers, a perennial species native to the New World. Results of microscopic and PCR analyses, combined with examination of gross morphology of the pseudoflowers, provide evidence that the fungus had established a systemic infection in both Xyris species, sterilized them and formed fungal pseudoflowers containing both mating type idiomorphs. Fusarium xyrophilum cultures also produced the auxin indole-3-acetic acid (IAA) and the cytokinin isopentenyl adenosine (iPR). Field observations revealed that pseudoflowers and Xyris flowers were both visited by bees. Together, the results suggest that F. xyrophilum pseudoflowers are a novel floral mimicry system that attracts insect pollinators, via visual and olfactory cues, into vectoring its conidia, which might facilitate outcrossing of this putatively heterothallic fungus and infection of previously uninfected plants" |
| Keywords: | *Biological Mimicry Flowers/*anatomy & histology/growth & development Fusarium/genetics/*growth & development Guyana Plant Leaves/genetics/growth & development/microbiology Poaceae/*anatomy & histology/genetics Pollination/genetics Seeds/genetics/growth &; |
| Notes: | "MedlineLaraba, Imane McCormick, Susan P Vaughan, Martha M Proctor, Robert H Busman, Mark Appell, Michael O'Donnell, Kerry Felker, Frederick C Catherine Aime, M Wurdack, Kenneth J eng Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. 2020/09/22 Fungal Genet Biol. 2020 Nov; 144:103466. doi: 10.1016/j.fgb.2020.103466. Epub 2020 Sep 19" |
