Slot Martijn, Kitajima Kaoru
Department of Biology, University of Florida, Gainesville, FL 32611, USA.
Funct Plant Biol. 2015 Jun;42(6):579-588. doi: 10.1071/FP14329.
Plant respiration plays a critical role in the C balance of plants. Respiration is highly temperature sensitive and small temperature-induced increases in whole-plant respiration could change the C balance of plants that operate close to their light-compensation points from positive to negative. Nonstructural carbohydrates are thought to play an important role in controlling respiration and its temperature sensitivity, but this role has not been studied at the whole-plant level. We measured respiration of whole Ardisia crenata Sims. seedlings and tested the hypothesis that darkness-induced C starvation would decrease the temperature sensitivity of whole-plant respiration. Compared with control plants, sugar and starch concentrations in darkened plants declined over time in all organs. Similarly, whole-plant respiration decreased. However, the temperature sensitivity of whole-plant respiration, expressed as the proportional increase in respiration per 10°C warming (Q10), increased with progressive C starvation. We hypothesise that growth respiration was suppressed in darkened plants and that whole-plant respiration represented maintenance respiration almost exclusively, which is more temperature sensitive. Alternatively, changes in the respiratory substrate during C starvation or increased involvement of alternative oxidase pathway respiration may explain the increase in Q10. Carbohydrates are important for respiration but it appears that even in C-starved A. crenata plants, carbohydrate availability does not limit respiration during short-term warming.
植物呼吸作用在植物的碳平衡中起着关键作用。呼吸作用对温度高度敏感，全株呼吸作用因温度小幅升高而产生的变化，可能会使接近光补偿点运行的植物的碳平衡从正值变为负值。非结构性碳水化合物被认为在控制呼吸作用及其温度敏感性方面发挥着重要作用，但这一作用尚未在全株水平上进行研究。我们测量了朱砂根幼苗的全株呼吸作用，并检验了以下假设：黑暗诱导的碳饥饿会降低全株呼吸作用的温度敏感性。与对照植株相比，遮光处理植株所有器官中的糖和淀粉浓度均随时间下降。同样，全株呼吸作用也降低了。然而，全株呼吸作用的温度敏感性，以每升温10°C时呼吸作用的比例增加来表示（Q10），随着碳饥饿的加剧而增加。我们推测，遮光处理植株的生长呼吸作用受到抑制，全株呼吸作用几乎完全代表维持呼吸作用，而维持呼吸作用对温度更为敏感。另外，碳饥饿期间呼吸底物的变化或交替氧化酶途径呼吸作用参与度的增加，可能解释了Q10的升高。碳水化合物对呼吸作用很重要，但即便在碳饥饿的朱砂根植株中，短期内升温期间碳水化合物的可利用性似乎也不会限制呼吸作用。
