绿盲蝽危害对枣树叶片生化指标的影响

绿盲蝽已在棉区爆发成灾,并逐渐向枣树等北方果树转移危害,已对我国北方果树生产造成严重威胁。绿盲蝽刺吸危害后,能诱导植物产生一系列生化反应。通过生物化学方法研究绿盲蝽不同危害程度对枣树叶片生化指标的影响,探讨受害枣树叶片对绿盲蝽危害的应激反应的变化规律。结果表明,受害枣树叶片内可溶性糖含量随着危害程度的加重先升高,后降低;蛋白质含量随受害程度的加重而呈现降低趋势;游离氨基酸含量随受害程度的加重逐渐升高。受害后枣树叶片内3种防御性酶随受害程度的加重发生不同程度的变化,超氧化物歧化酶(Superoxide Dismutase,SOD)的活性随着危害程度的加重先升高后下降;过氧化物酶(Peroxidase,POD)的活性总体升高;不同受害程度枣树叶片内过氧化氢酶(Catalase,CAT)的活性之间以及它们与未受害枣树叶片内过氧化氢酶(CAT)的活性之间均未达到显著性差异水平。总之,随着绿盲蝽危害程度的加重,枣树叶片内可溶性糖、蛋白质、游离氨基酸含量以及防御性酶活性发生了不同程度的变化,枣树叶片内除过氧化氢酶(CAT)的活性变化外,可溶性糖、游离氨基酸和蛋白质的含量变化以及超氧化物歧化酶(SOD)和过氧化物酶(POD)的活性变化与绿盲蝽危害胁迫有明显的关系,说明枣树叶片对绿盲蝽的危害胁迫产生了应激反应,且叶片内除过氧化氢酶(CAT)外的其他生化指标与绿盲蝽的不同危害程度有一定的相关性。研究结果为理解枣树受绿盲蝽危害后的应激反应机制提供了材料,对绿盲蝽可持续治理具有重要指导意义。

Physiological indices of leaves of jujube (Zizyphus jujuba) damaged by Apolygus lucorum

Apolygus lucorum Meyer-D?r (Hemiptera: Miridae) is an important type of pest, damaging various agricultural and forest crops such as cotton, fruits, and weeds. A. lucorum feeds on young buds, leaves, and various other tissues of host plants with its piercing and sucking mouthparts, and it is an important secondary insect pest in agricultural production in China. With the extensive cultivation of Bt cotton since 1997 in China, the wide-spread use of this insect-resistant cultivar has drastically reduced the need for insecticides to control many key lepidopteran pests. However, this reduction in insecticide use has led to increased population densities of various mirids, among which A. lucorum is considered as the most important pest in cotton production in northern China. The large-scale cultivation of fruits in recent years has provided abundant food and appropriate hibernacle for A. lucorum. Consequently, it has gradually become a significant pest for fruit trees, especially jujube (Zizyphus jujuba), causing serious damage in orchards in northern China. After being damaged by A. lucorum, the young leaves of jujube (Zizyphus jujuba) showed many needle-like reddish-brown dots, which formed into irregular holes as the leaves grew. Growth of the floral buds ceased, and black spots appeared on the young fruit. Many studies have shown that pest damage induces plants to produce stress responses. Therefore, certain physiological indices in plants will change during the response to pest damage. To examine the responses of jujube leaves to insect damage, we conducted biochemical analyses to study changes in various physiological indices of jujube leaves damaged to different degrees by A. lucorum. The soluble sugar content first increased and then decreased, while the protein content decreased and free amino acids content increased with increasing severity of leaf damage. The activities of protective enzymes also changed with increasing severity of leaf damage. Superoxide dismutase (SOD) activity first increased and then decreased, while peroxidase (POD) activity increased. The catalase (CAT) activity was not significantly different between damaged and undamaged jujube leaves. In summary, jujube leaves damaged by A. lucorum showed changes in soluble sugar, protein, and free amino acids contents, and changes in the activities of defense enzymes. Except for CAT, the changes in soluble sugar and protein contents and SOD and POD activities were closely related to the severity of damage to jujube leaves caused by A. lucorum. This indicates that jujube leaves responded to damage caused by A. lucorum, and showed significant changes in physiological indices (except CAT) in response to damage caused by A. lucorum. The results of this study help to clarify the mechanisms of the stress responses of jujube to damage caused by A. lucorum, and will be useful for developing strategies to control this important insect pest.