Stuart Emiko K, Plett Krista L
Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia.
Front Plant Sci. 2020 Jan 14;10:1658. doi: 10.3389/fpls.2019.01658. eCollection 2019.
Symbiosis with ectomycorrhizal (ECM) fungi is an advantageous partnership for trees in nutrient-limited environments. Ectomycorrhizal fungi colonize the roots of their hosts and improve their access to nutrients, usually nitrogen (N) and, in exchange, trees deliver a significant portion of their photosynthetic carbon (C) to the fungi. This nutrient exchange affects key soil processes and nutrient cycling, as well as plant health, and is therefore central to forest ecosystem functioning. Due to their ecological importance, there is a need to more accurately understand ECM fungal mediated C and N movement within forest ecosystems such that we can better model and predict their role in soil processes both now and under future climate scenarios. There are a number of hurdles that we must overcome, however, before this is achievable such as understanding how the evolutionary history of ECM fungi and their inter- and intra- species variability affect their function. Further, there is currently no generally accepted universal mechanism that appears to govern the flux of nutrients between fungal and plant partners. Here, we consider the current state of knowledge on N acquisition and transport by ECM fungi and how C and N exchange may be related or affected by environmental conditions such as N availability. We emphasize the role that modern genomic analysis, molecular biology techniques and more comprehensive and standardized experimental designs may have in bringing cohesion to the numerous ecological studies in this area and assist us in better understanding this important symbiosis. These approaches will help to build unified models of nutrient exchange and develop diagnostic tools to study these fungi at various scales and environments.
在养分有限的环境中，与外生菌根（ECM）真菌共生对树木而言是一种有利的伙伴关系。外生菌根真菌定殖于宿主植物的根系，帮助宿主获取养分，通常是氮（N），作为交换，树木将其光合作用产生的很大一部分碳（C）输送给真菌。这种养分交换影响着关键的土壤过程和养分循环，以及植物健康，因此对于森林生态系统的功能至关重要。由于它们在生态方面的重要性，有必要更准确地了解外生菌根真菌介导的碳和氮在森林生态系统中的移动情况，以便我们能够更好地模拟和预测它们目前以及在未来气候情景下在土壤过程中的作用。然而，在实现这一目标之前，我们必须克服许多障碍，比如了解外生菌根真菌的进化历史以及它们种间和种内的变异性如何影响其功能。此外，目前还没有一个被普遍接受的通用机制来调控真菌与植物伙伴之间的养分通量。在这里，我们考虑外生菌根真菌获取和运输氮的现有知识状况，以及碳和氮的交换如何与诸如氮有效性等环境条件相关或受其影响。我们强调现代基因组分析、分子生物学技术以及更全面和标准化的实验设计在整合该领域众多生态学研究方面可能发挥的作用，并帮助我们更好地理解这种重要的共生关系。这些方法将有助于建立养分交换的统一模型，并开发诊断工具，以便在不同尺度和环境下研究这些真菌。
