模拟酸雨对毛竹叶片抗氧化酶活性及释放绿叶挥发物的影响

为了探讨酸雨胁迫与毛竹(Phyllostachys pubescens)绿叶挥发物(green leaf volatiles, GLVs)释放规律以及抗氧化酶活性的关系, 通过盆栽试验, 采用不同pH值(5.6、4.0、2.5)的模拟酸雨对毛竹三年生实生苗进行处理, 研究酸雨对毛竹叶片可溶性蛋白质含量、丙二醛(MDA)含量和抗氧化酶活性的影响, 并采用热脱附/气相色谱/质谱联用技术对毛竹释放的GLVs成分和含量进行分析。结果表明: 酸雨胁迫下毛竹叶片MDA含量明显增加, pH 2.5模拟酸雨胁迫处理45天毛竹叶片MDA含量与对照相比增加了43.0% (p < 0.01); pH 4.0处理MDA含量增加缓慢, 处理75天时MDA含量比对照增加了0.36倍(p < 0.01)。pH 4.0和pH 2.5模拟酸雨胁迫处理45天时, 毛竹叶片可溶性蛋白质含量极显著增加, 与对照相比分别增加了32.0%和65.0% (p < 0.01)。在酸雨胁迫下, 毛竹叶片超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)的响应时间存在一定差异, 表现为互相协调, pH 2.5模拟酸雨胁迫处理SOD活性和POD活性分别在45天和60天时达到最大值, 分别为对照的1.67倍和1.31倍(p < 0.01), 随后降低。pH 4.0和pH 2.5模拟酸雨胁迫处理, 毛竹叶片GLVs含量比对照分别增加26.4%和132.9% (p < 0.01), 新增GLVs为 (E)-2-辛烯醛、2-乙基己醛、(E)-2-己烯醛和(E)-2-壬烯醛。研究表明: 酸雨胁迫条件下, 毛竹可以通过调节保护酶活性、可溶性蛋白质含量和释放GLVs来提高适应环境的能力。

Effects of simulated acid rain on the activity of antioxidant enzyme and the emission of induced green leaf volatiles in Phyllostachys pubescens

Aims In order to understand the effects of acid rain on Phyllostachys pubescens seedlings, we analyzed the composition and content of green leaf volatiles (GLVs) and the activity of antioxidant enzyme in 3-year-old seedlings of P. pubescens under simulated acid rain stress (i.e. at pH values of 5.6, 4.0 and 2.5). We aim to elucidate the adaptation mechanisms of P. pubescens leaves to acid rain stress from aspects of GLVs emission and their biochemical characteristics.Methods The composition and content of GLVs were analyzed under near-natural conditions using the thermal desorption system/gas chromatography/mass spectrometer technique (TDS-GC-MS), and the content of soluble protein and malondialdehyde (MDA), activity of antioxidant enzymes in the leaves of P. pubescens seedlings were measured under different acid rain treatments.Important findings Results showed that the MDA content did not respond to the pH 5.6 treatment in P. pubescens. The content of MDA was elevated in treatments of pH 4.0 and pH 2.5 after 75 days and 45 days, respectively (p < 0.01). The content of soluble protein in P. pubescens leaves was significantly influenced by acid rain; under the treatments of pH 4.0 and pH 2.5, the content of soluble protein was 32% and 65%, respectively, of the controls (p < 0.01). In the pH 5.6 treatment, the content of soluble protein was only slightly increased. There were differences in the timing of responses to acid rain stress among the activity of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), reflecting possibly a coordinative reaction of those antioxidant enzymes to stress. Compared with the control, GLVs were increased by 26.4% and 132.9% (p < 0.01), respectively, under the treatments of pH 4.0 and pH 2.5. (E)-2-nonenal, 2-ethyl-hexanal, 2-hexenal and (E)-2-nonenal were newly found GLVs under the acid rain stress. The results indicated that P. pubescens could enhance its ability to resist acid rain stress by adjusting its activities of antioxidant enzymes, improving contents of soluble protein and releasing GLVs.