Background & aims

Mycorrhizal fungi are well known to enhance nutrient acquisition through hyphal foraging beyond the root depletion zone. However, plant species vary widely in the degree to which they rely on mycorrhizal fungi for nutrient acquisition. Species which rely more on mycorrhizal colonization are expected to perform poorly in soils with lower density/availability of mycorrhizal partners. Mycorrhizal fungal density/availability is expected to be influenced by the mycorrhizal guild of dominant plant neighbors. However, little is known how the local density/availability of mycorrhizal partners may affect fungal colonization, root morphological traits and plant growth.

Methods

We inoculated seedlings of ectomycorrhizal (ECM) and arbuscular mycorrhizal (AM) tree species with soils from ECM-dominated forests or AM-dominated open fields. We evaluated seedling mycorrhizal colonization, root morphology and growth in response to these inocula.

Results

Both AM species (Acer rubrum L. and Ulmus americana L.) had higher AM colonization rates when inoculated with AM-dominated open field soils. However, only Acer grew better and invested less in autonomous root-based foraging, when inoculated with AM-dominated soils. Responses of ECM species to soil inocula were more nuanced. Both species remained unresponsive to inoculation treatment. Populus tremuloides Michx. ECM colonization was higher when inoculated with ECM-dominated soils, while neither root morphology nor mycorrhizal colonization responded to inoculum origin for Quercus rubra L.

Conclusion

Our results show that local variation in mycorrhizal fungal abundance does not necessarily lead to an integrated adjustment of autonomous foraging traits. In addition, we found that the variation in root colonization degree of seedlings from different species was not always accompanied with an increase of seedling performance.

中文翻译：

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来自丛枝和外生菌根为主的地点的土壤接种物对温带落叶林 4 种树苗的根系形态和生长的影响有限

 背景和目标

众所周知，菌根真菌可以通过菌丝在根耗尽区之外觅食来增强营养获取。然而，植物物种在依赖菌根真菌获取营养的程度上差异很大。预计更多依赖菌根定植的物种在菌根伴侣密度/可用性较低的土壤中表现不佳。预计菌根真菌密度/可用性将受到主要植物邻居的菌根公会的影响。然而，鲜为人知的是菌根伴侣的局部密度/可用性如何影响真菌定植、根形态特征和植物生长。

 方法

我们用来自 ECM 为主的森林或 AM 为主的开阔田地的土壤接种了外生菌根 （ECM） 和丛枝菌根 （AM） 树种的幼苗。我们评估了幼苗菌根定植、根形态和生长对这些接种物的响应。

 结果

当接种以 AM 为主的露地土壤时，两种 AM 物种 （Acer rubrum L. 和 Ulmus americana L.） 都具有较高的 AM 定植率。然而，只有 Acer 在接种 AM 为主的土壤时生长得更好，并且在基于根的自主觅食方面投入较少。ECM 物种对土壤接种物的反应更为微妙。两个物种对接种处理仍然无反应。Populus tremuloides （杨树）米奇克斯。当接种 ECM 为主的土壤时，ECM 定植较高，而根形态和菌根定植均未响应 Quercus rubra L 的接种来源。

 结论

我们的结果表明，菌根真菌丰度的局部变化不一定会导致自主觅食性状的综合调整。此外，我们发现不同物种幼苗根系定植程度的变化并不总是伴随着幼苗性能的增加。