Regulatory mechanisms underlying the maintenance of homeostasis in Pyropia haitanensis under hypersaline stress conditions
Regulatory mechanisms underlying the maintenance of homeostasis in Pyropia haitanensis under hypersaline stress conditions
复制标题
高盐胁迫条件下坛紫菜维持稳态的调控机制
DOI：
10.1016/j.scitotenv.2019.01.214
复制
发表时间：
2019-04-20
影响因子：
9.8
通讯作者：
Xie, Chaotian
中科院分区：
文献类型：
--
作者：
Wang, Wenlei;Xu, Yan;Xie, Chaotian
潮间带大型藻类对高盐胁迫条件具有很强的抵抗力。然而，其潜在机制仍不清楚。本研究以坛紫菜为材料，通过对坛紫菜在100%（HSS_100）和110%（HSS_110）两种高盐胁迫条件下的生理和转录变化的分析，探讨坛紫菜对高盐胁迫的响应机制。我们观察到Py.坛紫菜对HSS_100和HSS_110胁迫的响应主要涉及渗透调节、离子稳态和对次生胁迫的适应三个方面。首先，Py的保水性。通过在HSS_100条件下增加棒曲霉素的产量来维持Haitanensis的细胞壁果胶，而在HSS_110条件下需要通过增加果胶甲基酯酶抑制剂的丰度来保护细胞壁果胶免于水解。与此同时，Py。在HSS_100条件下，由于无机离子（K+、Na+、Cl-）和有机渗透调节物质（甘氨酸甜菜碱和海藻糖）的协同积累，坛紫菜实现了稳定而快速的渗透调节，而在HSS_110条件下则没有。第二，Py。与HSS_110条件相比，坛紫菜在HSS_100条件下保持了更高的K+/Na+比，这主要是通过将Na+输出到质外体而不是将其划分到液泡中，以及增强K+的吸收和保留。然而，K+/Na+稳态在短期暴露于HSS_110条件期间没有被完全破坏。最后是Py。在HSS_110条件下，Haitanensis的抗氧化系统清除了更多的ROS，合成了更多的热休克蛋白，尽管菌体在短期暴露于HSS_110条件下可能已经能够维持一定的氧化还原平衡。这些差异可以解释为什么Py。海坛紫菜能适应HSS_100环境而不是HSS_110环境，以及为什么暴露于HSS_110环境的菌体在转移到正常海水后能恢复。因此，本文提出的数据可能阐明的机制，使Pyropia物种容忍的突然和周期性的变化，盐度典型的潮间带系统。(C)2019爱思唯尔B. V.保留所有权利。
Intertidal macroalgae are highly resistant to hypersaline stress conditions. However, the underlying mechanism remains unknown. In the present study, the mechanism behind Pyropia haitanensis responses to two hypersaline stress conditions [100% (HSS_100) and 110% (HSS_110)] was investigated via analyses of physiological and transcriptomic changes. We observed that the differences between the responses of Py. haitanensis to HSS_100 and HSS_110 conditions involved the following three aspects: osmotic regulation, ionic homeostasis, and adjustment to secondary stresses. First, the water retention of Py. haitanensis was maintained through increased expansin production under HSS_100 conditions, while cell wall pectin needed to be protected from hydrolysis via the increased abundance of a pectin methylesterase inhibitor under HSS_110 conditions. Meanwhile, Py. haitanensis achieved stable and rapid osmotic adjustments because of the coordinated accumulation of inorganic ions (K+, Na+, and Cl-) and organic osmolytes (glycine betaine and trehalose) under HSS_100 conditions, but not under HSS_110 conditions. Second, Py. haitanensis maintained a higher K+/Na+ ratio under HSS_100 conditions than under HSS_110 conditions, mainly via the export of Na+ into the apoplast rather than compartmentalizing it into the vacuoles, and the enhanced uptake and retention of K+. However, K+/Na+ homeostasis was not completely disrupted during a short-term exposure to HSS_110 conditions. Finally, the Py. haitanensis antioxidant system scavenged more ROS and synthesized more heat shock proteins under HSS_100 conditions than under HSS_110 conditions, although thalli may have been able to maintain a certain redox balance during a short-term exposure to HSS_110 conditions. These differences may explain why Py. haitanensis can adapt to HSS_100 conditions rather than HSS_110 conditions, and also why the thalli exposed to HSS_110 conditions can recover after being transferred to normal seawater. Thus, the data presented herein may elucidate the mechanisms enabling Pyropia species to tolerate the sudden and periodic changes in salinity typical of intertidal systems. (C) 2019 Elsevier B.V. All rights reserved.