光强对极北海带幼苗生长和生化特性的影响

Effects of Light Intensities on the Growth and Biochemical Characteristics of Laminaria hyperborea Young Seedling

中文关键词: 极北海带  光强  生长  生化组分  抗氧化系统

英文关键词: Laminaria hyperborea  Light intensity  Growth  Biochemical composition  Antioxidant system

中文摘要:

      通过探讨极北海带(Laminaria hyperborea)幼苗在不同光强下的相对生长速率(RGR)及生化指标的变化规律，以期获得适宜极北海带幼苗生长的光照范围，并揭示其对光照胁迫的生化响应机制。结果显示，在40~80 μmol photons/(m2·s)光强下，极北海带幼苗的RGR较高，表明此光强范围对其生长较有利，而RGR与丙二醛(MDA)含量呈显著负相关关系，表明细胞膜脂的过氧化作用可能是导致极北海带幼苗RGR降低的原因之一。极北海带幼苗中超氧阴离子(SA)含量与MDA含量呈极显著正相关关系，而超氧化物歧化酶(SOD)及过氧化氢酶(CAT)的比活力与SA含量及MDA含量均呈负相关关系(其中，CAT比活力与SA含量的相关性达到显著水平)，且过氧化物酶(POD)与SOD的比活力呈极显著正相关关系，表明SOD、CAT及POD对于极北海带幼苗中活性氧的清除均发挥着重要的作用，且SOD与POD有明显的协同作用。高光和弱光逆境均不利于极北海带幼苗中可溶性蛋白的积累，且均造成藻体中MDA的积累，表明在光照胁迫下幼苗的总代谢水平降低，而活性氧水平升高。在高光下，幼苗可通过增加类胡萝卜素含量及显著提高SOD及POD的比活力来降低藻体内活性氧水平，从而减轻光氧化伤害。在弱光下，幼苗可通过增加体内叶绿素a的含量以高效地捕获有限光能，但藻体的抗氧化酶比活力显著下降，从而造成其活性氧代谢发生了严重失衡，进而导致其细胞膜脂过氧化程度的加重。上述结果可为极北海带的人工育苗及海上养殖提供参考。

英文摘要:

      Laminaria hyperborea is an important commercial seaweed, which has great potential for seaweed bed construction and artificial cultivation in China. To verify the suitable light for the growth of L. hyperborea young seedlings and clarify the biochemical response mechanism under light stress, the relative growth rate and biochemical responses under different light intensities were studied. Under these experimental conditions, the main conclusions are as follows: Light was beneficial for the growth of L. hyperborea young seedlings in the range of 40~80 μmol photons/(m2·s). The relative growth rate showed significant negative interrelation with the content of malondialdehyde (MDA), which indicates that membrane lipid peroxidation may be one of the reasons contributing to the low relative growth rate of L. hyperborea young seedlings. An extremely significant positive correlation was found between the content of superoxide anion (SA) and the content of MDA of L. hyperborea young seedlings. The specific activity of superoxide dismutase (SOD) and catalase (CAT) were negatively correlated with the content of SA and MDA, respectively. And the negative relationship between the specific activity of CAT and the content of SA was significant. Moreover, an extremely significant and positive correlation was found between specific activity of peroxidase (POD) and SOD. It can be inferred from the above correlation analysis results that SOD, CAT and POD play important roles in removing reactive oxygen species (ROS) and there is a significant synergy between SOD and POD in L. hyperborea young seedlings. The light stress environment was not conducive to the accumulation of soluble protein resulting in the accumulation of MDA in L. hyperborea young seedlings, which indicates that the total metabolic level was reduced and the ROS level was increased in this environment. The content of carotenoid and the specific activity of SOD and POD in L. hyperborea young seedlings will increase so that the ROS level can be reduced under high light stress, thus relieving light oxidative damage. The content of chlorophyll-a of L. hyperborea young seedlings will increase so that it can capture the limited light energy more effectively under low light stress. However, the antioxidant enzyme activity was significantly decreased as a result that led to a serious imbalance of ROS metabolism under low light stress, which resulted in more severe membrane lipid peroxidation damage. These results can provide the theoretical basis for the artificial breeding and cultivation of L. hyperborea in the future.