State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Yangling 712100, China.
Department of Agroecology, University of Bayreuth, Bayreuth 95440, Germany.
Plant Physiol. 2021 Nov 3;187(3):1519-1533. doi: 10.1093/plphys/kiab328.
Arbuscular mycorrhizal fungi (AMF) regulate soil nutrient cycling, directly supplying a host plant with nitrogen (N). AMF can also affect the outcome of interspecific interactions, but a mechanistic understanding of how soil N availability affects AMF-mediated interspecific relationships is currently lacking. We selected one dominant (Bothriochloa ischaemum; C4 grass) and one subordinate (Lespedeza davurica; legume) species in a natural grassland climax community to investigate the mechanism by which AMF influence interspecific interaction (mixed and monoculture) under three levels of N addition (0, low, and high N addition). Under the non-N addition treatment, AMF preferentially supplied N to the roots of B. ischaemum at the expense of N uptake by L. davurica, resulting in inhibited AMF benefits for L. davurica shoot growth. Under the low N addition treatment, interspecific interaction via AMF promoted L. davurica growth. Compared to the non-N addition treatment, N addition largely mitigated the effects, both positive (for B. ischaemum) and negative (for L. davurica), of AMF-mediated interspecific interaction on plant N uptake via AMF. When soil N availability severely limited plant growth, preferential N supply to the C4 grass by AMF was important for maintaining the abundance of the dominant species. When the N limitation for plant growth was alleviated by N addition, the interaction between AMF and soil microorganisms improved nutrient availability for the legume by stimulating activity of the enzyme responsible for soil organic matter mineralization, which is important for maintaining the abundance of the subordinate species. These data could influence strategies for maintaining biodiversity.
丛枝菌根真菌 (AMF) 调节土壤养分循环，直接为宿主植物提供氮 (N)。AMF 还可以影响种间相互作用的结果，但目前缺乏关于土壤 N 有效性如何影响 AMF 介导的种间关系的机制理解。我们选择了天然草地演替群落中的一种优势种（双穗雀稗；C4 草）和一种亚优势种（胡枝子；豆科），在三种氮添加水平（0、低氮和高氮添加）下，研究 AMF 如何影响种间相互作用（混合和单种培养）的机制。在非氮添加处理下，AMF 优先向 B. ischaemum 的根系供应 N，而抑制 L. davurica 对 N 的吸收，导致 AMF 对 L. davurica 地上生长的促进作用受到抑制。在低氮添加处理下，通过 AMF 的种间相互作用促进了 L. davurica 的生长。与非氮添加处理相比，氮添加在很大程度上减轻了 AMF 介导的种间相互作用对植物通过 AMF 吸收 N 的正（对 B. ischaemum）负（对 L. davurica）影响。当土壤 N 有效性严重限制植物生长时，AMF 优先向 C4 草供应 N 对于维持优势种的丰度很重要。当氮添加缓解了植物生长的氮限制时，AMF 与土壤微生物之间的相互作用通过刺激负责土壤有机质矿化的酶的活性来提高养分的有效性，这对于维持亚优势种的丰度很重要。这些数据可能会影响维持生物多样性的策略。
