二斑叶螨为害对草莓叶片H2O2、MDA含量以及部分防御酶活性的影响

本文旨在探究二斑叶螨Tetranychus urticae为害对草莓Fragaria×ananassa Duch.叶片内过氧化氢（H2O2）、丙二醛（MDA）含量以及部分防御酶活性的影响。在草莓苗上接种不同数量（5~25头）的二斑叶螨，分别在接种后的24 h、48 h和72 h取样，分析草莓叶片内H2O2、MDA的含量以及部分防御酶的活性。结果显示，二斑叶螨为害的草莓叶片内H2O2和MDA的含量以及超氧化物歧化酶（SOD）的活性随着时间的延长而呈现先升后降的趋势，在二斑叶螨持续为害草莓叶片24 h、48 h和72 h时，受损草莓叶片中H2O2的含量均显著高于对照（P<0.05），不同密度二斑叶螨为害的草莓叶片中H2O2的含量均显著高于对照（P<0.05），但与取食时间关系不大。当为害时间达到48 h时，MDA的含量和SOD的活性均达到最高峰，此时它们均与二斑叶螨的密度密切相关。当二斑叶螨为25头/叶时，MDA的含量和SOD的活性分别约是对照的3.6倍和10倍。过氧化物酶（POD）和过氧化氢酶（CAT）的活性随时间延长不断升高，均在二斑叶螨为害72 h时达到最高峰。同时，二斑叶螨的为害时间和为害密度之间存在一定的交互作用。以上结果表明草莓叶片主要通过调节其体内H2O2和MDA的含量以及各种防御酶活性的变化，对二斑叶螨的为害产生应激反应。

Effects of Tetranychus urticae feeding on the H2O2, MDA content and some defensive enzyme activities in strawberry leaves

This paper aimd to explore the effects of Tetranychus urticae damage on the content of hydrogen peroxide (H2O2), malondialdehyde (MDA) and some defensive enzyme activities in strawberry leaves. Inoculate strawberry seedlings with different numbers (5~25) of T. urticae, and sample at 24 h, 48 h and 72 h after inoculation. The content of H2O2, MDA and the changes of some defensive enzyme activities in strawberry leaves were analyzed. The results showed that the content of H2O2 and MDA in the leaves of strawberries damaged by T. urticae and the activity of superoxide dismutase (SOD) showed a trend of first increasing and then decreasing with time. When T. urticae continued to damage strawberry leaves for 24 h, 48 h and 72 h, H2O2 content in the damaged strawberry leaves was significantly higher than control (P<0.05).The content of H2O2 in strawberry leaves damaged by different densities of T. urticae was significantly higher than control (P<0.05), but it had little relationship with feeding time. When the damage time reached 48 h, MDA content and SOD activity both reached the highest peaks. At this time, they were closely related to the density of T. urticae. When there were 25 spider mites per leaf, the content of MDA and the activity of SOD were about 3.6 times and 10 times than control, respectively. The activities of peroxidase (POD) and catalase (CAT) continued to increase with time, and both reached their peaks at 72 h after the damage of T. urticae. At the same time, there was a certain interaction between the damage time and damage density of T. urticae. The results indicated that strawberry leaves had a stress response to the damage of T. urticae by regulating the contents of H2O2 and MDA and the changes in the activities of various defense enzymes in their bodies.