College of Horticulture and Gardening, Yangtze University, Jingzhou, 434025, Hubei, China.
School of Biological Sciences, University of Western Australia, Perth, Western Australia, 6009, Australia.
Microb Ecol. 2023 Aug;86(2):1023-1034. doi: 10.1007/s00248-022-02153-y. Epub 2022 Dec 6.
Soil water stress (WS) affects the decomposition of soil organic carbon (SOC) and carbon (C) emissions. Glomalin, released by arbuscular mycorrhizal fungi into soil that has been defined as glomalin-related soil protein (GRSP), is an important pool of SOC, with hydrophobic characteristics. We hypothesized that mycorrhizal fungi have a positive effect on SOC pools under soil WS for C sequestration in GRSP secreted by extraradical mycorrhizal hyphae. A microsystem was used to establish a root chamber (co-existence of roots and extraradical mycorrhizal hyphae) and a hyphal chamber (the presence of extraradical mycorrhizal hyphae) to study changes in plant growth, leaf water potential, soil aggregate stability, SOC, GRSP, C concentrations in GRSP (C), and the contribution of C to SOC after inoculating Rhizophagus intraradices with trifoliate orange (Poncirus trifoliata) in the root chamber under adequate water (AW) and WS. Inoculation with R. intraradices alleviated negative effects on leaf water potential and plant growth after 7 weeks of WS. Soil WS decreased SOC and mean weight diameter (MWD), while AMF inoculation led to an increase in SOC and MWD in both chambers, with the most prominent increase in the hyphal chamber under WS. The C concentration in easily extractable GRSP (EE-GRSP) and difficultly extractable GRSP (DE-GRSP) was 7.32 - 12.57 and 24.90 - 32.60 mg C/g GRSP, respectively. WS reduced C, while AMF mitigated the reduction. Extraradical mycorrhizal hyphae increased GRSP production and C, along with a more prominent increase in DE-GRSP under WS than under AW. Extraradical mycorrhizal hyphae increased the contribution of C to SOC only under WS. C and C were significantly positively correlated with SOC and MWD. It is concluded that extraradical mycorrhizal hyphae prominently promoted C sequestration of recalcitrant DE-GRSP under soil WS, thus contributing more organic C accumulation and preservation in aggregates and soil C pool.
土壤水分胁迫（WS）会影响土壤有机碳（SOC）的分解和碳（C）排放。球囊霉素相关土壤蛋白（GRSP）是由丛枝菌根真菌（AMF）释放到土壤中的一种重要的 SOC 库，具有疏水性。我们假设，在土壤 WS 下，外生菌根菌丝会分泌 GRSP 以固定 C，这对 SOC 库有积极影响。我们使用微系统建立了一个根室（根系和外生菌根菌丝共存）和一个菌丝室（仅存在外生菌根菌丝），以研究在充足水分（AW）和 WS 条件下接种三叶橙（Poncirus trifoliata）根室内的植物生长、叶片水势、土壤团聚体稳定性、SOC、GRSP、GRSP 中 C 浓度（C）以及 C 对 SOC 的贡献的变化。接种 R. intraradices 可缓解 WS 后 7 周对叶片水势和植物生长的负面影响。WS 降低了 SOC 和平均重量直径（MWD），而 AMF 接种增加了 SOC 和 MWD，在 WS 下菌丝室内增加更为明显。易提取 GRSP（EE-GRSP）和难提取 GRSP（DE-GRSP）中的 C 浓度分别为 7.32-12.57 和 24.90-32.60mg C/g GRSP。WS 降低了 C，而 AMF 减轻了这种降低。外生菌根菌丝增加了 GRSP 的产生和 C，在 WS 下比在 AW 下 DE-GRSP 的增加更为明显。只有在 WS 下，外生菌根菌丝才会增加 C 对 SOC 的贡献。C 和 C 与 SOC 和 MWD 呈显著正相关。结论是，外生菌根菌丝在土壤 WS 下显著促进了难分解的 DE-GRSP 的碳固定，从而增加了团聚体和土壤 C 库中更多的有机碳积累和保存。
