Plant fungal relationships should vary with abiotic and biotic factors to minimise plant stress and are likely to vary seasonally and with age. We investigated how fungal colonisation, specifically arbuscular mycorrhizal fungi and dark septate fungal endophytes, would vary with species identity and season, and how these interactions change with ontogeny. Plant roots of adults and seedlings of 9 species were collected from heathland and coastal dune habitats along the Australian east coast in New South Wales. Roots were stained and investigated for arbuscular mycorrhizal fungi and dark septate endophyte structures to determine colonisation strength. Species identity was the most important factor driving colonisation strength, while low rainfall and heatwaves were associated with declining arbuscular mycorrhizal fungi colonisation in the warmest sampling period. AMF colonisation may be supressed by plants under heat and water stress as a way of avoiding loss of limited photosynthates. Dark septate endophyte colonisation was more common in this time period and may assist with the stress of the warmer, drier conditions. Colonisation by arbuscular mycorrhizal fungi differed with age but in unpredictable ways and, along with dark septate endophytes, was evident even in plants that are considered non-mycorrhizal, although more extensive in known mycorrhizal species. The lack of arbuscular mycorrhizal fungi colonisation and the increase in dark septate endophyte colonisation during the most stressful period suggest an uncoupling mechanism in the symbiotic relationship which needs further investigation.

中文翻译：

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不同年龄的澳大利亚本土植物中真菌定植的季节性模式

植物真菌的关系应随非生物和生物因素而变化，以最大程度地减少植物胁迫，并可能随季节和年龄而变化。我们调查了真菌定植，特别是丛枝菌根真菌和深色分隔真菌内生菌如何随物种的身份和季节而变化，以及这些相互作用如何随个体发生而变化。从新南威尔士州澳大利亚东海岸的欧石南丛生地和沿海沙丘生境中采集成年植物的根和9种树苗。根被染色并研究丛枝菌根真菌和深色分隔的内生菌结构以确定定植强度。物种身份是驱动殖民化强度的最重要因素，在最温暖的采样期内，低降雨和热浪与丛枝菌根真菌的定殖减少有关。为了避免有限的光合产物的损失，植物在热和水分胁迫下可以抑制AMF的定殖。在此时间段内，深色分隔的内生菌定植更为普遍，并且可能有助于温暖，干燥条件下的压力。丛枝菌根真菌的定植随年龄而变化，但以不可预测的方式发生，并且与深色的隔生内生菌一起即使在被认为是非菌根的植物中也很明显，尽管在已知的菌根物种中更为广泛。