Universidad Autónoma de Baja California, Instituto de Investigaciones Oceanológicas, 22830, Ensenada, Baja California, Mexico.
Universidad Autónoma de Baja California, Instituto de Investigaciones Oceanológicas, 22830, Ensenada, Baja California, Mexico.
Mar Environ Res. 2021 Dec;172:105501. doi: 10.1016/j.marenvres.2021.105501. Epub 2021 Oct 11.
Intertidal seagrasses are subjected to desiccation and direct solar radiation during low tides. It is assumed that the canopy structure can self-protect the underlying shoots during these events, although there is no evidence on a physiological basis. The physiological responses of the surfgrass Phyllospadix torreyi were examined when emerged during low tide, on i) shoots overlaying the canopy, and ii) shoots sheltered within the canopy. Leaf water potential and water content decreased in external leaves after emersion, and the higher concentration of organic osmolytes reflected osmoregulation. Additionally, these shoots also exhibited a drastic reduction in carbohydrates after re-immersion, likely from cellular damage. Lipid peroxidation and antioxidant activity increments were also detected, while photosynthetic efficiency strongly diminished from direct exposure to solar radiation. Conversely, the sheltered shoots did not dehydrate and solely accumulated some oxidative stress, likely resulting from the warming of the canopy. In conclusion, the leaf canopy structure buffers physiological stress in the sheltered shoots, thus acting as a self-protective mechanism to cope with emersion.
潮间带海草在退潮时会经历干燥和直接的太阳辐射。虽然没有生理基础上的证据，但人们假设冠层结构可以在这些事件中自我保护下层的芽。当 surfgrass Phyllospadix torreyi 在退潮时露出水面时，研究了其生理反应，一是在冠层上的芽，二是在冠层内的芽。在露出水面后，外部叶片的叶水势和含水量下降，有机渗透物的高浓度反映了渗透调节。此外，这些芽在重新浸入水中后也会急剧减少碳水化合物，可能是由于细胞损伤。还检测到脂质过氧化和抗氧化活性的增加，而光合作用效率则因直接暴露在太阳辐射下而大大降低。相反，被遮蔽的芽不会脱水，只会积累一些氧化应激，可能是由于冠层变暖所致。总之，叶片冠层结构缓冲了遮蔽芽的生理压力，因此是一种应对暴露的自我保护机制。
