Facultad de Agronomía, IFEVA, Universidad de Buenos Aires, CONICET, -Buenos Aires, Argentina.
School of Agriculture and Environment, Faculty of Science, The University of Western Australia, Crawley, Western Australia, Australia.
Plant Biol (Stuttg). 2023 Oct;25(6):842-847. doi: 10.1111/plb.13558. Epub 2023 Jul 12.
The movement of gases within plants is crucial for species that live in flood-prone areas with limited soil oxygen. These plants adapt to hypoxia/anoxia not by using oxygen more efficiently, but by ensuring a steady oxygen supply to their cells. Wetland plants typically form gas-filled spaces (aerenchyma) in their tissues, providing a low-resistance pathway for gas movement between shoots and roots, especially when the shoots are above water, and the roots are submerged. Oxygen movement in plant roots is mainly through diffusion. However, in certain species, such as emergent and floating-leaved plants, pressurized flows can also facilitate the movement of gases within their stems and rhizomes. Three types of pressurized (convective) flows have been identified: humidity-induced pressurization (positive pressure), thermal osmosis (positive pressure with air flow against the heat gradient), and venturi-induced suction (negative pressure) caused by wind passing over broken culms. A clear diel variation in pressurized flows exists, with higher pressures and flows during the day and negligible pressures and flows during the night. This article discusses some key aspects of these mechanisms for oxygen movement.
植物内部气体的流动对于生活在洪水泛滥、土壤含氧量有限地区的物种至关重要。这些植物不是通过更有效地利用氧气来适应缺氧/无氧环境，而是通过确保细胞有稳定的氧气供应。湿地植物通常在组织中形成充满气体的空间（气腔），为茎和根之间的气体流动提供低阻力途径，特别是当茎部高于水面而根部被淹没时。氧气在植物根部的移动主要通过扩散。然而，在某些物种中，如挺水植物和浮叶植物，加压流也可以促进其茎和根茎内部气体的流动。已经确定了三种加压（对流）流：湿度诱导加压（正压）、热渗透（与热梯度相反的空气流的正压）和文丘里抽吸（由于风经过破碎的茎秆而产生的负压）。加压流存在明显的昼夜变化，白天压力和流量较高，夜间压力和流量可忽略不计。本文讨论了这些氧气运动机制的一些关键方面。
