余敏　杜照奎　王丽佳　祝庆

摘要：為探讨外源一氧化氮（NO）提高红树植物抗低温的生理机制，以秋茄（Kandelia obovata）为试验材料，对其施加不同浓度（0、0.1、0.5、1.0和1.5 mmol/L）的外源NO供体（SNP），并进行4 ℃低温处理，研究外源NO对低温胁迫下秋茄幼苗叶片的相对电导率、丙二醛（MDA）含量、抗氧化酶活性和渗透调节物质含量的影响。结果表明，SNP处理降低了秋茄幼苗叶片相对电导率和MDA含量，提高了叶片超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）和抗坏血酸过氧化物酶（APX）的活性以及可溶性蛋白质、可溶性糖和游离脯氨酸的含量，从而降低了低温胁迫对秋茄幼苗的伤害，以0.5 mmol/L SNP处理效果最佳。低温胁迫下，适宜浓度的外源NO通过提高抗氧化酶活性，促进渗透调节物质的合成，降低膜透性和膜脂过氧化水平，保护了细胞膜结构的稳定性，从而提高秋茄幼苗抗低温胁迫的能力。

关键词：红树植物；秋茄（Kandelia obovata）；低温；外源硝普钠；抗氧化酶；渗透调节物质

中图分类号：Q949.761.7；Q945.78 文献标识码：A 文章编号：0439-8114（2017）03-0490-04

DOI：10.14088/j.cnki.issn0439-8114.2017.03.024

Physiological Mechanism of Exogenous Nitric Oxide on Alleviating Low Temperature Stress of Kandelia obovata

YU Mina，DU Zhao-kuia，b，c，WANG Li-jiaa，ZHU Qinga

（a.School of Life Sciences； b.Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and Conservation；c.Institute of Ecology， Taizhou University， Taizhou 318000， Zhejiang， China）

Abstract： Aiming to explore the physiological mechanism of exogenous NO donor sodium nitroprusside（SNP） improving the ability of low temperature endurance of mangrove，Kandelia obobata seedlings were chosen as experimental materials，different concentrations of sodium nitroprusside（SNP）（0，0.1，0.5，1.0 and 1.5 mmol/L） was employed as exogenous nitric oxide（NO） donor to study the effects of different concentrations of exogenous NO on the plant relative electrical conductivity，MDA content，the activities of antioxidative enzymes and the contents of osmotic adjustment substance of K. obovata seedlings under 4 ℃ low-temperature stress. The results showed that，the treatment of SNP could reduce the relative electrical conductivity and content of MDA； increase the activities of SOD，POD，CAT and APX， and the content soluble protein， soluble sugar and free praline of the seedlings under low-temperature stress to reduce the damage caused by chilling. It was also found that the cold resistance effect of treatment with 0.5 mmol/L SNP was the best. It indicated that the exogenous NO with proper concentration could enhance the K. obovata seedlings adaptability for low temperature stress through improving the activities of antioxidative enzymes， increasing the osmotic adjustment substance contents， to reduce membrane lipid peroxidation and protecting the stability of cell membrane structure.

Key words： mangrove； Kandelia obovata； low temperature； exogenous sodium nitroprusside； antioxidative enzyme； osmotic adjustment substance

红树林处于热带、亚热带海洋和陆地过渡区，是一种低纬度海岸带地区特殊的湿地生态系统，具有调节环境气候、维护生态的多样性、防浪稳固海岸、抵抗自然灾害、降解环境污染、为人类提供多样的生物资源等多功能[1]。秋茄（Kandelia obovata）是红树科秋茄属植物，也是在中国分布最广泛的红树林种类[2]，多见于中国东南沿海地区，如海南、广西、广东、台湾、福建和浙江等地。鉴于秋茄重要的生态功能和价值，人们一直致力于其向高纬度地区引种。秋茄虽是众多红树植物中耐寒性最强的种类，但高纬度地区冬季极端低温天气会使得秋茄遭受到冻害，甚至引起植株的死亡。……