黄瓜对B型和Q型烟粉虱取食的不同生理生化反应

Differential Physiological and Biochemical Responses of Cucumber to the Feeding by Bemisia tabaci B and Q Biotypes

【目的】烟粉虱(Bemisia tabaci)B生物型(中东-小亚细亚1种)和Q生物型(地中海种)是农业生产上的重要害虫,杀虫剂的滥用造成害虫产生抗药性,并危害到生态安全与人类健康,因此,制定安全有效的防控措施十分必要。利用植物抗性是害虫综合治理的重要方面,论文旨在探讨黄瓜植株被B型、Q型烟粉虱取食后营养和防御相关酶系的反应差异,阐明黄瓜植株应对烟粉虱取食防御反应的生理生化机制,为利用植物抗性防控不同烟粉虱生物型提供依据。【方法】以实验室长期培养的B型、Q型烟粉虱和黄瓜博杰1号品种为供试材料,在黄瓜植株4片真叶期分别接B型、Q型烟粉虱成虫200头,同时分别以不接虫的黄瓜植株为对照,在烟粉虱持续取食1、3、5、7、9 d后,分别测定黄瓜叶片中营养物质(可溶性糖和可溶性蛋白质)含量、多酚含量、防御物质合成相关酶活性以及保护酶活性。【结果】在整个实验期内,B型烟粉虱取食3 d后,黄瓜叶片中可溶性糖和蛋白含量均显著高于对照植株,而Q型烟粉虱取食1 d后,黄瓜叶片内可溶性糖和蛋白质含量均比对照植株显著下降。黄瓜叶片中多酚含量及其合成关键酶苯丙氨酸解氨酶(PAL)活性在两种生物型烟粉虱取食后均升高,但对Q型烟粉虱取食更敏感,即活性更高。B型烟粉虱取食后引起黄瓜叶片中超氧化物歧化酶(SOD)和过氧化氢酶(CAT)酶活性均升高、过氧化物酶(POD)酶活性下降;而Q型烟粉虱取食后则引起SOD活性升高、POD和CAT酶活性下降。【结论】烟粉虱B型和Q型取食诱导黄瓜的营养物质含量、防御酶或保护酶活性发生不同变化。B型、Q型烟粉虱取食均能诱导黄瓜植株防御物质多酚的合成,导致叶片内多酚含量升高;但二者对黄瓜营养物质及保护酶的活性诱导存在差异,B型烟粉虱诱导黄瓜营养物质增加,Q型取食导致营养物质下降,而黄瓜防御物质在Q型烟粉虱取食后活性更强。两种烟粉虱生物型在寄主适应性上存在差异,在制定防治策略上,应该因不同烟粉虱生物型或不同寄主植物而有所不同。

[ Objective ] B （Middle East-Asia Minor 1） and Q （Mediterranean） biotypes, two cryptic species of Bernisia tabaci species complex, are important agricultural pests. Extensive applications of insecticides for control of the pests have resulted in pesticide resistance in the whiteflies, have endangered ecological safety and human health. Implementation of safe pest management strategy is therefore becoming very important and urgent. Utilization of plant defense is one of the important components in integrated pest management. The objective of this study is to investigate the differential responses of nutrients and defensive enzymes in cucumber induced by the feeding of B. tabaci B and Q biotypes and thereby to elucidate the physiological and biochemical mechanism underlying defence responses of cucumber to B. tabaci. [ Method ] Adults of B. tabaci B and Q biotypes and cucumber plants （var. Bojie-I） from the laboratory cultures were used for the experiments. The cucumber plants at four-leaf stage were respectively used to feed 200 adults ofB. tabaci B and Q biotypes, with healthy plants as controls, and the contents of nutrients （soluble sugar and soluble protein） and polyphenolic contents, activity of phenylalanine ammonialyase （PAL）, the enzyme of defensive substance biosynthesis, and activity of protective enzymes in cucumber were determined after continuously feeding for 1, 3, 5, 7 and 9 days by B and Q biotypes ofB. tabaci. [Result] Within the experimental period, the contents of soluble sugar and protein in cucumber increased after 3 d by B. tabaci B biotype, but decreased after 1 d by B. tabaci Q biotype, compared to those in controls. The contents of polyphenols and activity of PAL, the key enzyme in its biosynthesis pathway, increased after infested both by B and Q biotypes, with higher activities to Q biotype feeding. The activity of superoxide dismutase （SOD） and catalase （CAT） increased and the activity of peroxidase （POD） decreased after feeding by B biotype, while the activities of SOD increased and the activity of POD and CAT decreased after feeding by Q biotype. [Conclusion] Differential changes of nutrients and defensive enzymes in cucumber after the feeding ofB. tabaci B and Q biotypes were found in the present study. Both B and Q biotypes ofB. tabaci were able to induce the synthesis of defensive substance polyphenols, and increased the content of polyphenols in cucumber; but there were differences in inducing the contents of nutrients and the activities of protective enzymes, i.e., more nutrients in cucumber by B biotype feeding, while higher activities of defensive enzymes by Q biotype feeding. Those different changes in induced physiological and biochemical responses in plants to the herbivore may result from the difference in host plant adaptability between B and Q biotypes of B. tabaci. These results provide a basis for pest management strategies, especially for utilization of plant defense as the main control tactic, so as to target different biotypes ofB. tabaci on different host plants.