Roets, FrancoisTheron, NatalieWingfield, Michael J.Dreyer, Leanne Laurette2012-04-132012-04-132012-01F. Roets, N. Theron, M.J. Wingfield & L.L. Dreyer, Biotic and abiotic constraints that facilitate host exclusivity of Gondwanamyces and Ophiostoma on Protea, Fungal Biology, vol. 116, no. 1, pp. 49-61 (2012), doi:10.1016/j.funbio.2011.09.008.1878-6146 (print)1878-6162 (online)10.1016/j.funbio.2011.09.008http://hdl.handle.net/2263/18555Estimations of global fungal diversity are hampered by a limited understanding of the forces that dictate host exclusivity in saprobic microfungi. To consider this problem for Gondwanamyces and Ophiostoma found in the flower heads of Protea in South Africa, we determined the role of various factors thought to influence their host exclusivity. Results showed that various biotic and abiotic factors influence the growth and survival of these fungi in vitro. Monitoring temperature and relative humidity (RH) fluctuations within infructescences in vivo revealed considerable microclimatic differences between different Protea spp. Fungal growth and survival at different RH levels experienced in the field suggested that this factor does not play a major role in host exclusivity of these fungi. Maximum temperatures within infructescences and host preferences of the vectors of Gondwanamyces and Ophiostoma appear to play a substantial part in determining colonisation of Protea in general. However, these factors did not explain host exclusivity of specific fungal species towards particular Protea hosts. In contrast, differential growth of fungal species on media containing macerated tissue of Protea showed that Gondwanamyces and Ophiostoma grow best on tissue from their natural hosts. Thus, host chemistry plays a role in host exclusivity of these fungi, although some species grew vigorously on tissue of Protea spp. with which they are not naturally associated. A combination of host chemistry and temperature partially explains host exclusivity, but the relationship for these factors on the tested saprobic microfungi and their hosts is clearly complex and most likely includes combinations of various biotic and abiotic factors including those emerging from this study.en© 2011 The British Mycological Society. Published by Elsevier Ltd. All rights reserved. Notice : this is the author’s version of a work that was accepted for publication in Fungal Biology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Fungal Biology, vol. 116, issue 1, January 2012, doi:10.1016/j.funbio.2011.09.008GondwanamycesHost chemistryOphiostoma -- Host plantsCryptobiosisHost-fungus relationshipsPlants -- Effect of mycotoxins onProteaceae -- Diseases and pestsPostprint Article