顽拗性黄皮种子脱水过程中活性氧清除酶活性的变化

以正常性种子花生为对照，研究了顽拗性黄皮种子脱水过程中活性氧清除酶、膜脂过氧化作用以及电解质渗漏率的变化。随着含水量的下降，黄皮胚的电解质渗漏率和膜脂过氧化产物丙二醛(MDA)含量均显著增加；当黄皮胚含水量下降至40％后，SOD活性开始急剧下降，而POD和CAT活性在胚含水量下降过程中呈现出缓慢下降的趋势。花生胚在含水量从45％降至14％的过程中，电解质渗漏率没有明显增加，MDA含量只有少量增加；当含水量降至14％后，电解质渗漏率出现少量增加。花生胚脱水初期，活性氧清除酶活性明显增加，并在整个脱水过程中维持较高的水平。以上结果表明顽拗性种子黄皮的脱水敏感性与活性氧清除酶相对活性变化有关。脱水引起黄皮胚活性氧清除酶活性降低，活性氧清除能力下降，膜脂过氧化作用加强，膜透性增大。黄皮胚的膜系统可能是脱水伤害的靶位之一。

Changes in Activity of Reactive-oxygen-scavenging Enzymes in Recalci-trant Wampee (Clausena lansium) Seeds During Desiccation

The activity of reactive oxygen scavenging enzymes, membrane lipid peroxidation and electrolyte leakage in embryos of wampee seeds during desiccation were measured in order to investigate the physiology of desiccation sensitivity in recalcitrant seeds. Experimental results indicated that electrolyte leakage markedly increased with decreased moisture content in wampee embryos. Membrane lipid peroxidation, as quantified by measurement of malondialdehyde (MDA) content, was also increased as a result of desiccation. As the embryos were dried to a moisture content of 40%, the activity of superoxide dismutase (SOD) decreased rapidly. Peroxidase (POD) and catalase (CAT) activities decreased slowly during embryo desiccation. The electrolyte leakage of peanut seeds (control) did not rise significantly until embryos were dried to 14% moisture content. During the process of water loss from 45% to 14%, MDA content in peanut embryos increased only slightly. Activities of scavenging enzymes in peanut embryos increased markedly in an early stage of desiccation, and were maintained at a high level during the entire process of desiccation. Based on these results, it could be concluded that desiccation sensitivity of wampee seeds was related to changes in activities of scavenging enzymes.