红树植物淹水胁迫响应研究进展

Mechanisms of mangroves waterlogging resistance

潮汐淹水是红树植物面临的主要环境胁迫之一,也是导致目前红树林造林成活率低的一个关键因子。由于长期适应于水淹生境,红树植物发育出一套适应于潮间带生长的抗淹水机制。综述了与红树植物相关的抗淹水胁迫响应机制,包括了形态结构、生长、水分和光合作用、膜脂过氧化系统和根系脱氢酶系统、内源激素和胁迫多胺等5个方面。提出应用人工潮汐系统研究红树植物的淹水抗性机理是确定不同种类红树植物的耐淹水能力的有效手段。并指出生长的研究是淹水胁迫响应研究的基础,而与分子手段相结合的激素水平的研究将在红树植物抗性胁迫研究中得到重视。

Tidal waterlogging is one of the most important stresses to mangroves. The duration of waterlogging is a limiting factor for the survival of mangrove seedlings. On adapting to waterlogging in the intertidal zones, mangroves have developed a set of mechanisms of waterlogging resistance, such as the growth of aerial roots and air space in the roots, special photosynthesis rates and nutrient circle. Scientists have shown great interesting in mangroves waterlogging resistance. The present paper reviews five aspects of the mechanisms of mangroves in responses to waterlogging, which are morphological and anatomical factors, growth, water use efficiency and photosynthesis, activities of alcohol dehydrogenase and enzymes processing reactive oxygen species, and plant growth regulators. Aerial roots and aerenchyma in cortex are important for mangroves＇ resistance to waterlogging, by allowing oxygen to be replenished. Under tidal flooding, oxygen transported in the aerenchyma can maintain the oxygen demand of the roots. Like other stress, under waterlogging conditions the growth of mangroves falls, the photosynthetic rate declines, and leaves pigment contents change. In addition, the activities of enzymes processing reactive oxygen species and of dehydrogenase change. These physiological and photosynthetic responses of mangroves facilitate their tolerance to waterlogging. The plant growth regulator abscisic acid is also greatly induced by waterlogging. However, no reports about the relationship between content of ethylene or polyamine and waterlogging in mangroves have been reported. To investigate waterlogging resistance mechanisms of mangroves, artificial tidal equipment is useful. It simplifies the conditions, and simulates different kinds of tidal cycles, including different durations of waterlogging. We find it necessary to study further the growth of mangroves to waterlogging, because it is the base for plant resistance research. Similarly, studies on plant hormone combined with molecular techniques will be of great interest in research on mangroves waterlogging. Further studies should be focused on the molecular mechanisms of hormone changes in mangroves during waterlogging. Studies on the mechanisms of mangroves waterlogging resistance will provide theoretical guidance for mangroves rehabilitation.