为了探讨海藻糖在大型藻类抗逆中的作用及其机制，实验利用生理生化分析、高效液相色谱-串联质谱(LC-MS/MS)、荧光定量PCR (qRT-PCR)方法分析了外源海藻糖对高温胁迫下大型海藻龙须菜生长、抗逆相关物质和酶活性、植物激素及相关基因表达的影响。结果发现，外源添加10 mmol/L海藻糖使龙须菜的相对生长速率和脯氨酸含量分别升高0.34倍(3 d)和0.30倍(24 h)，叶绿素荧光参数、超氧化物歧化酶和海藻糖-6-磷酸合成酶活性升高，但丙二醛含量和脂氧合酶(LOX)活性降低。同时，海藻糖激活了龙须菜中水杨酸代谢关键酶——异分支酸合成酶的活性及其基因表达，促进了水杨酸的积累(2.05倍)。此外，海藻糖可以使热激蛋白70基因表达稳定升高、lox2基因表达下调(12 h)。可见，外源海藻糖可以通过清除活性氧自由基，降低膜脂过氧化，促进渗透保护物质和抗逆植物激素水杨酸的积累等来促进高温下龙须菜的生长。本研究证明了海藻糖在龙须菜抗高温胁迫中具有重要作用，为龙须菜的抗逆育种工作提供了参考。

Gracilariopsis lemaneiformis is a kind of cultivated seaweed with the second highest production in China, which is mainly used to feed abalone and extract agar, but its yield and cultivated period are limited due to the high temperature of the summer in the southern coast. As a signaling molecule, non-reducing disaccharide trehalose plays an important role in enduring high temperature, drought and other adverse stresses. To explore the role and mechanism of trehalose in the stress resistance of G. lemaneiformis, this paper investigated the effects of exogenous trehalose on the growth, stress resistance-related substances, metabolic enzymes, endogenous salicylic acid and related genes under high temperature stress using physiological and biochemical test, HPLC-MS/MS and real-time fluorescent quantitative PCR (qRT-PCR). The results showed that application of 10 mmol/L trehalose promoted the algal growth and proline content of G. lemaneiformis with 0.34-fold (3 d) and 0.30-fold increases(24 h) compared to the control, respectively. Meanwhile, trehalose significantly activated the chlorophyll fluorescence parameters and the activities of superoxide dismutase and trehalose-6-phosphate synthase, but malonaldehyde content and lipoxidase (LOX) activity were reduced. Moreover, trehalose significantly stimulated the activity and gene expression of isochorismate synthase, the key enzyme in salicylic acid biosynthesis, and the accumulation of salicylic acid (2.05-fold). Finally, supplementation with trehalose could maintain the stable increase of the gene expression level of heat shock protein 70, while the lox2 gene expression was downregulated at 12 h. All of these results revealed that trehalose could promote algal growth through scavenging the reactive oxygen species, alleviating the lipid peroxidation of the cell membrane, enhancing the accumulation of osmolytes and phytohormones and so on. This study verifies that exogenous trehalose plays a vital role in resisting high temperature, which will provide a reference for future breeding efforts to improve the stress resistance of G. lemaneiformis.

Q 786；S 968.43

国家重点研发计划(2018YFD0901502)；宁波市重大科技创新项目(2019B10009)；宁波市重大科技攻关项目(2021Z114, 2022Z172)