Forestry and Natural Resources, College of the Redwoods, Eureka, CA, 95501, USA.
School of Forest Resources and Environmental Science, Michigan Technological University, Houghton, MI, 49931, USA.
Plant Cell Environ. 2018 Mar;41(3):504-516. doi: 10.1111/pce.13098. Epub 2017 Dec 11.
We investigated the occurrence of and mechanisms responsible for acclimation of fine-root respiration of mature sugar maple (Acer saccharum) after 3+ years of experimental soil warming (+4 to 5 °C) in a factorial combination with soil moisture addition. Potential mechanisms for thermal respiratory acclimation included changes in enzymatic capacity, as indicated by root N concentration; substrate limitation, assessed by examining nonstructural carbohydrates and effects of exogenous sugar additions; and adenylate control, examined as responses of root respiration to a respiratory uncoupling agent. Partial acclimation of fine-root respiration occurred in response to soil warming, causing specific root respiration to increase to a much lesser degree (14% to 26%) than would be expected for a 4 to 5 °C temperature increase (approximately 55%). Acclimation was greatest when ambient soil temperature was warmer or soil moisture availability was low. We found no evidence that enzyme or substrate limitation caused acclimation but did find evidence supporting adenylate control. The uncoupling agent caused a 1.4 times greater stimulation of respiration in roots from warmed soil. Sugar maple fine-root respiration in warmed soil was at least partially constrained by adenylate use, helping constrain respiration to that needed to support work being performed by the roots.
我们研究了成熟糖枫（Acer saccharum）根系呼吸在经过 3 年以上的实验性土壤增温（+4 至+5°C）与土壤湿度增加的综合处理后适应的发生和机制。热呼吸适应的潜在机制包括酶活性的变化，通过根氮浓度来表示；底物限制，通过检查非结构性碳水化合物和外源糖添加的影响来评估；以及腺嘌呤控制，通过检查根系呼吸对呼吸解偶联剂的反应来评估。细根呼吸对土壤增温的部分适应导致比预期的 4 至 5°C 温度升高（约 55%）时的特定根呼吸增加小得多（14%至 26%）。当环境土壤温度较高或土壤水分供应较低时，适应最大。我们没有发现酶或底物限制导致适应的证据，但确实发现了支持腺嘌呤控制的证据。解偶联剂导致增温土壤中根系呼吸的刺激增加了 1.4 倍。变暖土壤中的糖枫细根呼吸至少部分受到腺嘌呤利用的限制，有助于将呼吸限制在根系进行的工作所需的范围内。
