温度和光强对海带新品系“黄官2号”幼孢子体的生长和生理生化特性的影响

Effects of temperature and light intensity on the growth and physiological and biochemical characteristics of young sporophyte of a novel Saccharina japonica “Huangguan No.2”

关键词:  海带  温度  光照强度  生长  生化组分  叶绿素荧光参数

Key words:  Saccharina japonica  Temperature  Light intensity  Growth  Biochemical composition  Chlorophyll fluorescence parameter

摘要:

为探明“黄官2号”海带(Saccharina japonica)幼孢子体(3~4 cm)生长适宜的光、温条件及其生理生化机制，本研究开展“黄官2号”海带幼孢子体在不同光强和温度下相对生长速率(RGR)、叶绿素荧光参数、色素/蛋白含量、活性氧含量、抗氧化剂含量和抗氧化酶活性等生长和生理生化特性的相关研究。结果显示，RGR受光强、温度及二者交互作用影响显著，影响程度由大到小依次为温度、光强、二者交互作用。在10~13 ℃、60~90 μmol photons/(m2·s)条件下，“黄官2号”海带幼孢子体RGR较高，高温(16 ℃和19 ℃)组的RGR则在30 μmol photons/(m2·s)下较高。在同一温度下，随光强升高，海带幼孢子体的叶绿素a和类胡萝卜素含量逐渐下降，超氧化物歧化酶(SOD)活性和抗坏血酸(AsA)含量呈上升趋势；在同一光强下，相对于10~13 ℃，高温组可溶性蛋白含量减少，丙二醛和过氧化氢含量显著升高，抗氧化酶(SOD、谷胱甘肽过氧化物酶、抗坏血酸过氧化物)活性和抗氧化物质(AsA和类胡萝卜素)含量均较高。高温和高光[120 μmol photons/(m2·s)]组的光系统Ⅱ最大量子产量(Fv/Fm)均显著降低，表明藻体在高温高光胁迫下光能转换效率降低。而高光组的调节性能量耗散的量子产量显著增大，且快速光曲线初始斜率(α)显著降低，表明“黄官2号”幼孢子体的光保护系统对高光胁迫产生了积极响应，并通过降低光能利用效率降低了对光能的吸收，从而减少光损伤。高光、高温组的关键抗氧化酶活性和抗氧化物质含量均显著升高，表明“黄官2号”海带幼孢子体的抗氧化系统均对高光、高温逆境产生了积极响应以降低活性氧损害。低光[10 μmol photons/(m2·s)]组的Fv/Fm、α、光系统Ⅱ实际量子产量和叶绿素a含量均显著升高，表明“黄官2号”海带幼孢子体在弱光环境下的光能转换效率和光能利用效率均显著提升，从而增加对光能的吸收。上述对“黄官2号”海带幼孢子体在温度和光强条件下的生理、生态适应性研究为其海上栽培技术的优化提供了理论依据。

Abstract:

The study aimed to investigate the optimal light and temperature conditions, and physiological and biochemical mechanisms for the growth of young sporophytes (3–4 cm) of "Huangguan No.2". We conducted corresponding studies on the growth and physiological and biochemical conditions of young sporophytes under different light intensities and temperatures, including the relative growth rate (RGR), fluorescence parameter of chlorophyll, contents of pigments/proteins, reactive oxygen, antioxidants, and activity of antioxidant enzymes. The results showed that RGR was significantly affected by light, temperature, and their interaction. The degree of influence from large to small is temperature, light intensity and their interaction. They exhibited the highest RGR at 10–13 ℃ and 60–90 μmol photons/(m2·s), whereas the RGR of the high temperature (16 ℃ and 19 ℃) group was highest at 30 μmol photons/(m2·s). At the same temperature, the chlorophyll-a and carotenoid contents of young sporophytes decreased with increasing light intensity. Additionally, the SOD activities and ascorbic acid (AsA) contents tended to increase. Under the same light intensity, compared to 10–13 ℃, the contents of soluble protein decreased in the high temperature group; whereas the contents of MDA and H2O2 significantly increased. Additionally, the SOD, GSH-Px, and APX activities and antioxidant (AsA and carotenoids) contents were all higher. The maximum photochemical efficiency of photosystem Ⅱ (Fv/Fm) was significantly lower in the high temperature and high light [(120 μmol photons/(m2·s)] groups, indicating that the light energy conversion efficiency of the alga was reduced under high temperature and high light stress. In the high light group, the quantum yield of regulated non-photochemical energy loss in photosystem Ⅱ [Y(NPQ)] increased significantly and the initial slope (α) of the fast light curve decreased significantly. This suggests that the photoprotective system of young sporophytes of "Huangguan No.2" responded positively to the high light stress and reduced the absorption of light energy by lowering the efficiency of light energy utilization to reduce the photodamage. The activities of key antioxidant enzymes and the antioxidant contents in the high light and high temperature groups were significantly higher, indicating that the antioxidant systems of young sporophytes responded positively to high light and high temperature stresses to minimize the damage caused by reactive oxygen species. Under low light [10 μmol photons/(m2·s)] group, Fv/Fm, α, actual quantum yield of photosystem Ⅱ [Y(Ⅱ)], the chlorophyll-a contents significantly increased. This indicates that the light energy conversion efficiency and light energy utilization efficiency significantly increased in the low light environment, which led to an increase in the absorption of light energy. These results on the physiological and ecological adaptations of young sporophytes under the conditions of temperature and light intensity can provide a theoretical basis for further optimizing the light and temperature parameters of young sporophytes of "Huangguan No.2" during intermediate culture of young sporelings.