Biogeochemistry of Agroecosystems, Department of Crop Science, Georg August University of Göttingen, Göttingen, Germany.
College of Agronomy and Biotechnology, China Agricultural University, Beijing, China.
Plant Cell Environ. 2022 Oct;45(10):3122-3133. doi: 10.1111/pce.14413. Epub 2022 Aug 16.
Consequences of interactions between ectomycorrhizal fungi (EcMF) and non-mycorrhizal rhizosphere fungi (NMRF) for plant carbon (C) allocation belowground and nutrient cycling in soil remain unknown. To address this topic, we performed a mesocosm study with Norway spruce seedlings [Picea abies (L.) H. Karst] inoculated with EcMF, NMRF, or a mixture of both (MIX). CO pulse labelling of spruce was applied to trace and visualize the C incorporation into roots, rhizohyphosphere and hyphosphere. Activities and localization of enzymes involved in the C, nitrogen (N) and phosphorus (P) cycling were visualized using zymography. Spruce seedlings inoculated with EcMF and NMRF allocated more C to soils (EcMF: 10.7%; NMRF: 3.5% of total recovered C) compared to uninoculated control seedlings. The C activity in the hyphosphere was highest for EcMF and lowest for NMRF. In the presence of both, NMRF and EcMF (MIX), the C activity was 64% lower compared with EcMF inoculation alone. This suggests a suppressed C allocation via EcMF likely due to the competition between EcMF and NMRF for N and P. Furthermore, we observed 57% and 49% higher chitinase and leucine-aminopeptidase activities in the rhizohyphosphere of EcMF compared to the uninoculated control, respectively. In contrast, β-glucosidase activity (14.3 nmol cm h ) was highest in NMRF likely because NMRF consumed rhizodeposits efficiently. This was further supported by that enzyme stoichiometry in soil with EcMF shifted to a higher investment of nutrient acquisition enzymes (e.g., chitinase, leucine-aminopeptidase, acid phosphatase) compared to NMRF inoculation, where investment in β-glucosidase increased. In conclusion, the alleviation of EcMF from C limitation promotes higher activities of enzymes involved in the N and P cycle to cover the nutrient demand of EcMF and host seedlings. In contrast, C limitation of NMRF probably led to a shift in investment towards higher activities of enzymes involved in the C cycle.
外生菌根真菌 (EcMF) 和非菌根根际真菌 (NMRF) 之间的相互作用如何影响植物地下碳 (C) 分配和土壤养分循环尚不清楚。为了解决这个问题，我们进行了一个云杉苗[欧洲云杉 (Picea abies (L.) H. Karst)]的中尺度研究，这些苗被接种了 EcMF、NMRF 或两者的混合物 (MIX)。通过对云杉进行 CO 脉冲标记，追踪并可视化 C 掺入根、根-菌根区和菌根区的情况。利用同工酶法可视化参与 C、氮 (N) 和磷 (P) 循环的酶的活性和定位。与未接种对照苗相比，接种了 EcMF 和 NMRF 的云杉苗将更多的 C 分配到土壤中 (EcMF：总回收 C 的 10.7%；NMRF：3.5%)。EcMF 的菌根区的 C 活性最高，NMRF 的最低。当同时存在 NMRF 和 EcMF (MIX) 时，与单独接种 EcMF 相比，C 活性降低了 64%。这表明由于 EcMF 和 NMRF 对 N 和 P 的竞争，可能通过 EcMF 抑制了 C 的分配。此外，我们观察到与未接种对照相比，EcMF 中的几丁质酶和亮氨酸氨肽酶活性分别高出 57%和 49%。相比之下，β-葡萄糖苷酶活性 (14.3 nmol cm h) 在 NMRF 中最高，可能是因为 NMRF 有效地消耗了根分泌物。这进一步表明，与接种 NMRF 相比，EcMF 土壤中酶的化学计量学转向了更高的养分获取酶 (如几丁质酶、亮氨酸氨肽酶、酸性磷酸酶) 的投资，而接种 NMRF 时，β-葡萄糖苷酶的投资增加。总之，EcMF 从 C 限制中得到缓解，促进了参与 N 和 P 循环的酶的更高活性，以满足 EcMF 和宿主苗的养分需求。相比之下，NMRF 的 C 限制可能导致对参与 C 循环的酶的更高活性的投资发生转变。
