Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, No. 201 Jiufeng 1 Road, East Lake High-Tech Development Zone, Wuhan 430074, P.R. China.
College of Science, Tibet University, No. 10 Zangda East Road, Chengguan District, Lhasa 850000, P.R. China.
Tree Physiol. 2023 Nov 13;43(11):1903-1916. doi: 10.1093/treephys/tpad098.
Carbon (C) allocation plays an important role in plant adaptation to water and nutrient stresses. However, the effects of drought and nutrient deficiencies on the allocation of recently fixed C in the plant-soil-microbe system remain largely unknown. Herein, we studied the response of C allocation of Sophora moorcroftiana (an indigenous pioneer shrub in Tibet) to drought, nitrogen (N) deficiency and phosphorus (P) deficiency using a microcosm experiment. The 13CO2 continuous labeling was used to trace C allocation in the plant-soil-microbe system. We found that drought significantly reduced plant 13C, but it increased 13C accumulation in soil. The decreased plant 13C under drought was attributed to the decrease of 13C in stem and root rather than that in leaf. The excess 13C fraction in the microbial biomass (MB13C) was reduced by N deficiency, but it was not affected by the combination of drought and N deficiency, indicating that drought weakened the effects of N deficiency on MB13C. By contrast, MB13C increased under the combination of drought and P deficiency, suggesting that drought enhanced the effects of P deficiency on MB13C. Drought and nutrient deficiencies regulated the belowground 13C allocation. Specifically, drought and P deficiency increased the allocation of 13C to root and N deficiency regulated the allocation of 13C to microbial biomass C and dissolved organic C in soil. Notably, soil 13C decreased with increasing plant 13C, while MB13C first decreased and then increased with increasing plant 13C. Overall, our study demonstrated that drought and nutrient deficiencies interactively affected C allocation in a plant-soil-microbe system and provided insights into C allocation strategies in response to multiple resource (water and nutrient) stresses under environmental changes.
碳（C）分配在植物适应水和养分胁迫方面起着重要作用。然而，干旱和养分缺乏对植物-土壤-微生物系统中最近固定的 C 分配的影响在很大程度上尚不清楚。在此，我们通过微宇宙实验研究了干旱、氮（N）缺乏和磷（P）缺乏对西藏本土先锋灌木苦参（Sophora moorcroftiana）C 分配的响应。使用 13CO2 连续标记追踪植物-土壤-微生物系统中的 C 分配。我们发现干旱显著降低了植物的 13C，但增加了土壤中的 13C 积累。干旱下植物 13C 的减少归因于茎和根中 13C 的减少，而不是叶中 13C 的减少。N 缺乏会降低微生物生物量（MB13C）中的过量 13C 分数，但干旱和 N 缺乏的组合不会影响它，表明干旱削弱了 N 缺乏对 MB13C 的影响。相比之下，干旱和 P 缺乏的组合会增加 MB13C，表明干旱增强了 P 缺乏对 MB13C 的影响。干旱和养分缺乏调节了地下 13C 分配。具体来说，干旱和 P 缺乏增加了 13C 向根的分配，而 N 缺乏调节了 13C 向微生物生物量 C 和土壤中溶解有机碳的分配。值得注意的是，土壤 13C 随植物 13C 的增加而减少，而 MB13C 先减少后增加。总体而言，我们的研究表明，干旱和养分缺乏在植物-土壤-微生物系统中相互作用地影响 C 分配，并为在环境变化下应对多种资源（水和养分）胁迫的 C 分配策略提供了见解。
