Functional differentiation of arbuscular mycorrhizal fungi in top- vs. subsoil: do subsoils harbor nutrient acquisition traits supportive for sustainable agriculture?

在传统管理的农业系统中，单一作物种植和资源利用效率低下，伴随着土壤退化和土壤生物多样性丧失，对稳定粮食生产构成挑战。需要制定可持续战略，以确保粮食生产不会（进一步）损害农业生态系统的健康和功能。丛枝菌根真菌（AMF）是作物中分布最广的共生体，因其对植物营养、提高作物抗病性和改善土壤稳定性的有益作用而受到越来越多的关注。然而，大多数关于AMF对作物生产效益的研究都集中在表土，即常规管理系统中的薄犁层。农业底土（即犁层以下的矿质土）中AMF对可持续农业的潜力很少研究。虽然AMF丰度从表层到底土逐渐减少，但研究表明，底土可以承载一组独特的AMF类群，这些类群在性状和功能上与表层AMF不同。该项目的主要目的是研究土壤表层和底土AMF群落在养分获取和分配策略方面的功能分化。该项目旨在回答以下问题：(1)底土中AMF群落是否具有与表土中AMF群落不同甚至更多样化的功能特征，以及(2)这些特征是否有利于可持续管理。DNA扩增子测序和与不同植物功能群相关的AMF群落的亚转录组分析将基于植物和真菌之间基于性状的伴侣选择的假设，首次评估地下AMF群落的功能多样性。为了进一步的功能表征，利用富15n化合物和微量元素在养分吸收过程中充当K类似物，评估了底土AMF群落对速效氮和钾的吸收和转移。利用双同位素标记（15N, 33P）有机质，研究了AMF地下群落对有机质中N和P的动员作用。利用13co2脉冲标记，分析作物对不同土壤AMF群落的碳分配。该项目将深入了解地下土壤作为功能多样的AMF群落水库的潜力，以及它们改善农业系统养分利用的潜力。因此，该项目将有助于明确适当的底土管理是否适合促进农业系统中AMF的功能多样性，甚至针对特定的功能性状，以帮助稳定粮食生产。

Monocropping and inefficient resource utilization, accompanied by soil degradation and soil biodiversity loss in conventionally managed agricultural systems, pose challenges to stable food production. Sustainable strategies are needed to ensure food production without (further) compromising the health and functionality of agroecosystems. Arbuscular mycorrhizal fungi (AMF) are the most widespread symbionts among crops and have received increasing attention for their beneficial effects on plant nutrition, promotion of crop resistance, and improving soil stability. Most studies on the benefits of AMF for crop production, however, have focused on AMF in the topsoil, i.e., the thin plow layer in conventionally managed systems. The potential of AMF in agricultural subsoils (i.e., the mineral soil below the plow layer) for sustainable agriculture is rarely studied. While the abundance of AMF decreases from top- to subsoil, it has been shown that subsoils can host a unique set of AMF taxa that are assumed to differ in traits and functionality from topsoil AMF. The main objective of this project is the functional differentiation of top- and subsoil AMF communities with respect to their nutrient acquisition and allocation strategies. The project aims to answer the question of (i) whether subsoils harbor AMF communities with functional traits that are distinct from, or even more diverse than, AMF communities in topsoil, and (ii) whether these traits can be beneficial for sustainable management. DNA amplicon sequencing and metatranscriptome analysis of AMF communities associated to plants of different plant functional groups will allow a first assessment of the functional diversity of subsoil AMF communities, based on the assumption of a trait-based partner selection between plants and fungi. For a further functional characterization, the uptake and transfer of readily available N and K by subsoil AMF communities is assessed using 15N-enriched compounds and trace elements that act as K analogs during nutrient uptake. The stimulation of N and P mobilization from organic matter by AMF subsoil communities is investigated using dual isotopic labeled (15N, 33P) organic matter. With 13CO2-pulse labeling, the carbon allocation of crop plants to different subsoil AMF communities will be analyzed. The project will provide insights into the potential of subsoils as reservoirs for functionally diverse AMF communities and their potential to improve nutrient utilization in agricultural systems. Thereby, the project will help to clarify whether an adequate subsoil management is suitable to promote functional diversity of AMF in agricultural systems, or even target specific functional traits, to help stabilize food production.