外源茉莉酸对桑天牛成虫取食及桑枝内抗虫次生物质含量和防御酶活性的影响

Effects of Exogenous Jasmonic Acid on Feeding Area of Apriona germari Adult,Content of Anti-insect Secondary Metabolite and Activity of Defense Enzymes in Mulberry Branches

茉莉酸作为信号分子在提高植物抗虫性方面起着重要作用。通过取食选择试验调查分别经3种浓度茉莉酸处理不同时间的桑枝被桑天牛成虫取食的面积差异,在此基础上测定分析茉莉酸处理桑枝内具有抗虫活性的次生物质含量及防御酶活性动态变化。用10、100、1 000μmol/L茉莉酸处理24 h或48 h后,桑枝被桑天牛成虫取食的面积与对照组无显著差异;处理72 h后,仅1 000μmol/L茉莉酸处理组桑枝被桑天牛成虫取食的面积明显低于对照组。Sperman等级相关性分析表明,茉莉酸浓度与桑天牛成虫的取食面积呈极显著负相关。用1 000μmol/L茉莉酸处理4~72 h,桑枝内多酚氧化酶(PPO)活性均明显高于对照,且在48 h时达到最大值;脂氧合酶(LOX)活性仅在处理8 h时显著提高;胰蛋白酶抑制剂(TI)活性和单宁含量随着处理时间的延长逐渐提高,但仅在72 h时显著高于对照组;1 000μmol/L茉莉酸处理可提高桑枝内总酚含量,在处理48 h时达到显著程度,但在72 h又降低至与对照组相当的水平。研究结果表明,1 000μmol/L茉莉酸处理桑枝具有阻碍桑天牛成虫取食的效果,并可诱导桑枝内抗虫次生物质含量及防御酶活性显著提高。

Jasmonic acid （JA）, a defense signaling molecule, plays an important role in improving plant resistance against insects. Feeding choice test was employed to investigate the differences in the feeding area of Apriona germari adult on mulberry branches at different time points after treatment with three concentrations of JA. In addition, the dynam- ic changes of secondary metabolite content and defense enzyme activity in mulberry branches were measured after JA treatment. The feeding area of A. germari adult on mulberry branches, which were treated with 10, 100 and 1 000 μmol/L JA for 24 and 48 h respectively, was not significantly different with that in control group. The feeding area of A. germari adult on mulberry branches treated with 1 000 iJmol/L JA for 72 h was significantly lower than that of the control. By Spearman＇s rank correlation analysis, a signifi- cant negative correlation between JA concentration and the feeding area of A. germari adult was found. Within 4 h to 72 h after treated with 1 000 μmol/L JA, the activities of polyphenol oxidase （PPO） in mulberry branches was signifi- cantly higher than that of the control, and reached the highest value at 48 h after treatment. The activity of lipoxygenase （LOX） in mulberry branches was significantly higher than that of the control only at 8 h after treatment. The trypsin inhibi- tor （TI） activity and tannin content in mutberry branches were gradually increased with treatment duration. However, they were significantly higher than those of the control only at 72 h after JA treatment. The content of total phenols in mulberry branches was increased after 1 000 μmol/L JA treatment. It was significantly higher than that of the control at 48 h after treatment, while decreased to the control level at 72 h after treatment. The results showed that 1 000 μmol/L JA was able to induce mulberry branches to display a significant antifeedant activity against A. germari adult and significant elevation of secondary metabolite content and defense enzyme activity.