ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia.
Natural Resources Institute, Agriculture, Health and Environment Department, University of Greenwich, Kent, UK.
Plant Cell Environ. 2021 Jul;44(7):2090-2101. doi: 10.1111/pce.14018. Epub 2021 Feb 15.
Mitochondrial respiration (R) is central to plant physiology and responds dynamically to daily short-term temperature changes. In the longer-term, changes in energy demand and membrane fluidity can decrease leaf R at a common temperature and increase the temperature at which leaf R peaks (T ). However, leaf R functionality is more susceptible to short-term heatwaves. Catalysis increases with rising leaf temperature, driving faster metabolism and leaf R demand, despite declines in photosynthesis restricting assimilate supply and growth. Proteins denature as temperatures increase further, adding to maintenance costs. Excessive heat also inactivates respiratory enzymes, with a concomitant limitation on the capacity of the R system. These competing push-and-pull factors are responsible for the diminishing acceleration in leaf R rate as temperature rises. Under extreme heat, membranes become overly fluid, and enzymes such as the cytochrome c oxidase are impaired. Such changes can lead to over-reduction of the energy system culminating in reactive oxygen species production. This ultimately leads to the total breakdown of leaf R, setting the limit of leaf survival. Understanding the heat stress responses of leaf R is imperative, given the continued rise in frequency and intensity of heatwaves and the importance of R for plant fitness and survival.
线粒体呼吸（R）是植物生理学的核心，它会对日常短期的温度变化做出动态响应。从长期来看，能量需求和膜流动性的变化会降低在共同温度下的叶片 R，并增加叶片 R 峰值出现的温度（T）。然而，叶片 R 的功能更容易受到短期热浪的影响。随着叶片温度的升高，催化作用会增强，尽管光合作用会限制同化产物的供应和生长，从而导致代谢和叶片 R 需求更快，但这会增加呼吸作用的负担。随着温度的进一步升高，蛋白质会变性，增加维持成本。此外，呼吸酶也会因过热而失活，从而限制了 R 系统的能力。这些相互竞争的推拉力因素导致叶片 R 速率随温度升高而逐渐减缓。在极端高温下，膜变得过于流动，细胞色素 c 氧化酶等酶也会受到损害。这些变化会导致能量系统过度还原，最终导致活性氧物质的产生。这最终会导致叶片 R 的完全崩溃，从而设定叶片存活的极限。鉴于热浪的频率和强度持续增加，以及 R 对植物适应力和生存的重要性，了解叶片 R 的耐热应激反应至关重要。
