《植物生理学报》 2014, 50(10): 1555-1562

外源水杨酸对镉胁迫下甜瓜幼苗生长、光合作用和活性氧代谢的缓解效应

张永平¹, 范红伟², 杨少军¹, 陈幼源^1,*

¹上海市农业科学院园艺研究所, 上海市设施园艺技术重点实验室, 上海201403; ²上海市农业技术推广服务中心, 上海201103

通信作者：陈幼源；E-mail: yy12@saas.sh.cn；Tel: 021-52630133

摘　要：

以甜瓜耐镉品种‘哈密绿’和镉敏感品种‘秀绿’为试验材料, 在人工气候箱内采用基质栽培法, 研究了外源水杨酸(SA)处理对镉(Cd)胁迫下甜瓜幼苗生长、光合作用和活性氧代谢的缓解效应。结果显示: 与对照(CK)比较, Cd处理显著抑制了甜瓜幼苗的生长和光合作用, 降低了叶绿素含量, 抗氧化酶活性、脯氨酸(Pro)含量、丙二醛(MDA)含量和超氧阴离子(O₂ ¯• )产生速率增加; 在Cd胁迫下, SA处理可以有效促进甜瓜幼苗的生长, 增加了叶绿素含量、净光合速率(P_n)、气孔导度(G_s)、蒸腾速率(T_r)、气孔限制值(L_s)和水分利用效率(WUE), 降低了胞间CO₂浓度(C_i); 提高了超氧化物歧化酶(SOD)、过氧化酶酶(POD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX), 增强植株抗氧化能力, 使Pro和可溶性蛋白含量升高, MDA含量和O₂ ¯•产生速率下降, 能有效抑制镉胁迫引起的膜脂过氧化伤害; 镉敏感品种‘秀绿’变化幅度大于耐镉品种‘哈密绿’。研究结果说明, SA有利于甜瓜幼苗在Cd胁迫下活性氧代谢的提高和对光能的捕获与转换, 促进了甜瓜幼苗的生长, 降低Cd胁迫对甜瓜幼苗的抑制作用, 且对镉敏感品种‘秀绿’效果大于耐镉品种‘哈密绿’。

关键词：外源水杨酸; 甜瓜; 镉胁迫; 光合作用; 活性氧代谢

收稿：2014-04-18   修定：2014-08-18

资助：上海市西甜瓜产业体系项目、上海市科技成果转化项目(123919N1800)和上海市闵行区科技项目(2012MH102)。

Alleviating Effects of Exogenous Salicylic Acid on Growth, Photosynthesis and Reactive Oxygen Metabolism in Melon Seedlings under Cadmium Stress

ZHANG Yong-Ping¹, FAN Hong-Wei², YANG Shao-Jun¹, CHEN You-Yuan^1,*

¹Shanghai Key Laboratory of Protected Horticultural Technology, Horticultural Research Institute, Shanghai Academy of Agricultural Sciences, Shanghai 201403, China; ²Shanghai Agriculture Technology Extension and Service Center, Shanghai 201103, China

Corresponding author: CHEN You-Yuan; E-mail: yy12@saas.sh.cn; Tel: 021-52630133

Abstract:

The experiment was carried out by ‘Hamilü’ (cadmium-tolerant) and ‘Xiulü’ (cadmium-sensitive) in climate chambers and substrates to investigate the alleviating effects of exogenous salicylic acid (SA) on melon seedlings for growth, photosynthesis and reactive oxygen metabolism under cadmium stress. The results showed that under Cd stress, melon-seedling growth, photosynthesis and chlorophyll contents were decreased, the antioxidant enzyme activities, proline, MDA content and O₂ ¯• producing rate were increased. SA could increase melon-seedling growth, chlorophyll contents, net photosynthetic rate (P_n) , stomatal conductance (G_s), transpiration rate (T_r), stomatal limitation (L_s) and water use efficiency (WUE), while reduce intercellular carbon dioxide concentration (C_i) under cadmium stress. SA also raised leaf the activity of superoxid dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX), proline and soluble protein content, reduced MDA content and O₂ ¯• producing rate, suppressed the membrane lipid peroxidation under cadmium stress. Under cadmium stress condition, we not only found that SA caused enhancement in photosynthesis and antioxidant enzyme activity of two melon genotypes, but also found that the enhancement of cadmium-sensitive ‘Xiulü’ was higher than cadmium-tolerant ‘Hamilü’. Obviously, SA was favorable for the seedlings to increase the growth and reactive oxygen metabolism, capture and converse solar energy, thus improving melon growth and abating the inhibitory effects of cadmium stress on melon, These findings suggested that ameliorative effect of SA on melon seedlings with cadmium stress was effective, especially for cadmium -sensitive genotypes.

Key words: exogenous salicylic acid; melon; cadmium stress; photosynthesis; reactive oxygen metabolism