Endo Hikaru, Moriyama Hikari, Okumura Yutaka
Faculty of Fisheries, Kagoshima University, Kagoshima 890-0056, Japan.
United Graduate School of Agricultural Sciences, Kagoshima University, Kagoshima 890-0056, Japan.
Antioxidants (Basel). 2023 Feb 2;12(2):357. doi: 10.3390/antiox12020357.
Plants and brown algae avoid photoinhibition (decline in photosystem II efficiency, /) caused by excess light energy and oxidative stress through several photoprotective mechanisms, such as antioxidant xanthophyll production and heat dissipation. The heat dissipation can be measured as non-photochemical quenching (NPQ) and is strongly driven by de-epoxidation of xanthophyll cycle pigments (XCP). Although NPQ is known to increase under high light acclimation and nutrient-deficient conditions, a few studies have investigated the combined effects of the conditions on both NPQ and associated xanthophyll-to-chlorophyll (Chl) a ratio. The present study investigated the photosynthetic parameters of the brown alga acclimated to three irradiance levels combined with three nutrient levels. Elevated irradiance decreased / but increased NPQ, XCP/Chl ratio, and fucoxanthin/Chl ratio, suggesting the photoprotective role of antioxidant fucoxanthin in brown algae. Reduced nutrient availability increased NPQ but had no effect on the other variables, including XCP/Chl ratio and its de-epoxidation state. The results indicate that NPQ can be used as a sensitive stress marker for nutrient deficiency, but cannot be used to estimate XCP pool size and state.
植物和褐藻通过多种光保护机制避免光抑制（光系统II效率下降），这种光抑制是由过量光能和氧化应激引起的，例如抗氧化叶黄素的产生和热耗散。热耗散可以通过非光化学猝灭（NPQ）来衡量，并且受到叶黄素循环色素（XCP）脱环氧化的强烈驱动。尽管已知NPQ在高光适应和营养缺乏条件下会增加，但很少有研究调查这些条件对NPQ和相关叶黄素与叶绿素（Chl）a比值的综合影响。本研究调查了适应三种光照强度与三种营养水平组合的褐藻的光合参数。光照强度升高会降低/但会增加NPQ、XCP/Chl比值和岩藻黄质/Chl比值，这表明抗氧化岩藻黄质在褐藻中具有光保护作用。营养可用性降低会增加NPQ，但对其他变量没有影响，包括XCP/Chl比值及其脱环氧化状态。结果表明，NPQ可以用作营养缺乏的敏感应激标志物，但不能用于估计XCP库大小和状态。
