Biological Oceanography Division, CSIR-National Institute of Oceanography, Goa, 403004, India.
School of Biotechnology, Jawaharlal Nehru University, 110067, New Delhi, India.
Sci Rep. 2017 Nov 27;7(1):16430. doi: 10.1038/s41598-017-15994-2.
The survival of wetland plant species largely relies on physiological adaptations essential for submergence and desiccation. Intertidal seaweeds, unlike terrestrial plants, have unique adaptations to submergence and can also sustain desiccation arising from tidal rhythms. This study determined the differential metabolic regulations in the inter-tidal seaweed species Ulva lactuca against the submergence and desiccation. During desiccation, the relative water content of the algal thalli declined with concomitant increase in reactive oxygen species (ROS) and lipid peroxidation. Nevertheless, the trends reversed during recovery on re-submergence and attained homeostasis. Metabolite profiling of U. lactuca revealed desiccation induced balance in energy reserve utilization by adjusting carbohydrate metabolism and switch over to ammonia metabolism. Upon re-submergence, thalli showed an increase in fermentative metabolites, pyruvate-alanine conversion, and the GABA shunt. Prolonged submergence induced substrate level phosphorylation mediated sugar biosynthesis while continuing the alternative carbon flux through fermentative metabolism, an increase in osmoprotectants glycine and betaine, sulfur bearing compounds cysteine and hypotaurine, and phenolic compound coniferaldehyde. The determined metabolic regulations in U. lactuca for submergence tolerance provide insights into potential evolutionarily conserved protective mechanisms across the green lineage and also highlights the possible role of sulfur oxoforms as strong free radical scavengers.
湿地植物物种的生存在很大程度上依赖于对淹没和干燥至关重要的生理适应。与陆生植物不同，潮间带海藻具有对淹没的独特适应能力，也能承受因潮汐节律而产生的干燥。本研究确定了潮间带海藻物种浒苔对淹没和干燥的差异代谢调节。在干燥过程中，藻体的相对含水量随着活性氧 (ROS) 和脂质过氧化的增加而下降。然而，在重新淹没后的恢复过程中，这些趋势发生逆转并达到了平衡。浒苔的代谢物分析显示，干燥通过调整碳水化合物代谢和转向氨代谢来诱导能量储备利用的平衡。重新淹没后，藻体表现出发酵代谢物的增加、丙酮酸-丙氨酸转化和 GABA 支路。长时间的淹没诱导底物水平磷酸化介导的糖生物合成，同时通过发酵代谢继续进行替代碳通量，增加了甘氨酸和甜菜碱等渗透保护剂、含硫化合物半胱氨酸和次牛磺酸以及酚类化合物松柏醛。浒苔对淹没耐受性的确定代谢调节为整个绿色谱系中潜在的进化保守保护机制提供了深入了解，还强调了硫氧化形式作为强自由基清除剂的可能作用。
