Wen Zhihui, White Philip J, Shen Jianbo, Lambers Hans
College of Resources and Environmental Sciences, National Academy of Agriculture Green Development, Key Laboratory of Plant-Soil Interactions, Ministry of Education, China Agricultural University, 100193, Beijing, China.
Ecological Science Group, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK.
New Phytol. 2022 Feb;233(4):1620-1635. doi: 10.1111/nph.17854. Epub 2021 Dec 4.
The concept of a root economics space (RES) is increasingly adopted to explore root trait variation and belowground resource-acquisition strategies. Much progress has been made on interactions of root morphology and mycorrhizal symbioses. However, root exudation, with a significant carbon (C) cost (c. 5-21% of total photosynthetically fixed C) to enhance resource acquisition, remains a missing link in this RES. Here, we argue that incorporating root exudation into the structure of RES is key to a holistic understanding of soil nutrient acquisition. We highlight the different functional roles of root exudates in soil phosphorus (P) and nitrogen (N) acquisition. Thereafter, we synthesize emerging evidence that illustrates how root exudation interacts with root morphology and mycorrhizal symbioses at the level of species and individual plant and argue contrasting patterns in species evolved in P-impoverished vs N-limited environments. Finally, we propose a new conceptual framework, integrating three groups of root functional traits to better capture the complexity of belowground resource-acquisition strategies. Such a deeper understanding of the integrated and dynamic interactions of root morphology, root exudation, and mycorrhizal symbioses will provide valuable insights into the mechanisms underlying species coexistence and how to explore belowground interactions for sustainable managed systems.
根系经济空间（RES）的概念越来越多地被用于探索根系性状变异和地下资源获取策略。在根系形态与菌根共生的相互作用方面已经取得了很大进展。然而，根系分泌物以显著的碳（C）成本（约占总光合固定碳的5-21%）来增强资源获取，在这个RES中仍然是一个缺失环节。在这里，我们认为将根系分泌物纳入RES结构是全面理解土壤养分获取的关键。我们强调了根系分泌物在土壤磷（P）和氮（N）获取中的不同功能作用。此后，我们综合了新出现的证据，这些证据说明了根系分泌物在物种和个体植物水平上如何与根系形态和菌根共生相互作用，并讨论了在磷贫瘠与氮限制环境中进化的物种的不同模式。最后，我们提出了一个新的概念框架，整合了三组根系功能性状，以更好地把握地下资源获取策略的复杂性。对根系形态、根系分泌物和菌根共生的综合动态相互作用的更深入理解，将为物种共存的潜在机制以及如何探索地下相互作用以实现可持续管理系统提供有价值的见解。
