Department of Conservation Ecology and Entomology, Stellenbosch University, Private Bag X1, Stellenbosch, 7600, South Africa.
Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Stellenbosch, 7600, South Africa.
Antonie Van Leeuwenhoek. 2022 Jun;115(6):761-771. doi: 10.1007/s10482-022-01732-w. Epub 2022 Apr 7.
Fungi in the genera Knoxdaviesia and Sporothrix dominate fungal communities within Protea flowerheads and seed cones (infructescences). Despite apparently similar ecologies, they show strong host recurrence and often occupy the same individual infructescence. Differences in host chemistry explain their host consistency, but the factors that allow co-occupancy of multiple species within individual infructescences are unknown. Sporothrix splendens and K. proteae often grow on different senescent tissue types within infructescences of their P. repens host, indicating that substrate-related differences aid their co-occupancy. Sporothrix phasma and K. capensis grow on the same tissues of P. neriifolia suggesting neutral competitive abilities. Here we test the hypothesis that differences in host-tissues dictate competitive abilities of these fungi and explain their co-occupancy of this spatially restricted niche. Media were prepared from infructescence bases, bracts, seeds, or pollen presenters of P. neriifolia and P. repens. As expected, K. capensis was unable to grow on seeds whilst S. phasma could. As hypothesised, K. capensis and S. phasma had equal competitive abilities on pollen presenters, appearing to explain their co-occupancy of this resource. Growth of K. proteae was significantly enhanced on pollen presenters while that of S. splendens was the same as the control. Knoxdavesia proteae grew significantly faster than S. splendens on all tissue types. Despite this, S. splendens was a superior competitor on all tissue types. For K. proteae to co-occupy infructescences with S. splendens for extended periods, it likely needs to colonize pollen presenters before the arrival of S. splendens.
真菌属 Knoxdaviesia 和 Sporothrix 在普洛蒂亚花头和种子锥体（果实）内的真菌群落中占主导地位。尽管它们的生态环境显然相似，但它们表现出强烈的宿主重现性，并且经常占据同一个体的果实。宿主化学成分的差异解释了它们的宿主一致性，但允许多个物种在单个果实中共同占据的因素尚不清楚。Sporothrix splendens 和 K. proteae 经常在其 P. repens 宿主果实的不同衰老组织类型上生长，这表明与基质相关的差异有助于它们的共同占据。Sporothrix phasma 和 K. capensis 生长在 P. neriifolia 的相同组织上，表明它们具有中性竞争能力。在这里，我们检验了这样一个假设，即宿主组织的差异决定了这些真菌的竞争能力，并解释了它们在这个空间受限的生态位中的共同占据。从 P. neriifolia 和 P. repens 的果实基部、苞片、种子或花粉呈现器制备培养基。正如预期的那样，K. capensis 无法在种子上生长，而 S. phasma 可以。正如假设的那样，K. capensis 和 S. phasma 在花粉呈现器上具有相等的竞争能力，这似乎解释了它们对这种资源的共同占据。K. proteae 在花粉呈现器上的生长显著增强，而 S. splendens 的生长与对照相同。Knoxdavesia proteae 在所有组织类型上的生长速度都明显快于 S. splendens。尽管如此，S. splendens 在所有组织类型上都是一个更好的竞争者。为了让 K. proteae 与 S. splendens 长期共同占据果实，它可能需要在 S. splendens 到达之前殖民花粉呈现器。
