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The Effect of Greenhouse Whitefly on Secondary Metabolism of Glabrous Cucumber

Author: WangTao
Tutor: CaoChenXing
School: Shandong Agricultural University
Course: Olericulture
Keywords: Glabrous cucumber Greenhouse whitefly Resistance to pest PAL PPO POD Secondary metabolites
CLC: S436.421
Type: Master's thesis
Year: 2011
Downloads: 81
Quote: 2
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Abstract

Greenhouse whitefly(Trialeurodes vapotariorum) is a serious pest to cucumber in the world. With the rapid development of modern facility agriculture, more favorable conditions for reproduction of greenhouse whitefly was created, the damage appeared generally in northern China and was very seirous in some areas. There are rare researches on the resistance to whitefly and its resistance mechanism is unknown until now. The glabrous cucumber is a mutants of normal cucumber, it has the characteristic of ability of whitefly-resistance by field observation in field experiment. In this paper, with the rare mutant of cucumber, effects of secondary metabolites and related metabolic enzymes in glabrous cucumber and normal cucumber after greenhouse whitefly damaged was studied, the basis for the study on the defense response of cucumber after grennhouse whitefly fed and the insect-resistant mechanisms was provided. The main results were as follows:1 Glabrous cucumber could inhibit the growth of greenhouse whitefly, it had more strongly resistance to greenhouse whitefly reproduction than normal cucumber. Glabrous cucumber had the resistance to whitefly obviously and was the rare new materials for resistance to the insect.2 After greenhouse whitefly damage, the secondary metabolism enzyme activities and content of secondary metabolites in glabrous cucumber rapadly increased and transported, they actively cooperated to resist whitefly. The POD activity and its increment in glabrous cucumber were significantly higher than those of normal cucumber, PAL and PPO activity increased differently, but increments were higher than normal cucumber and the peaks of three types of enzyme activity in glabrous cucumber were ahead of normal cucumber. Thus the changes of PAL, PPO and POD activity in glabrous cucumber were closely related to ability of the anti-whitefly, and PAL, PPO and POD can be used as physiological indicators.3 The contents of lignin, tannins, total phenol and flavonoids in leaves of two types of cucumber increased to varying degrees,after greenhouse whitefly infestated. The contents of four substances in cucumber seedlings were increased firstly and then decreased, but they showed the bimodal curve in adult period, the contents of four substances decreased after inoculation for one day, then increased rapidly, the increments of glabrous cucumber were significantly higher than those of normal cucumber, the contents of four substances increased again, because nymph appeared and inoculated.Therefore, the changes of lignin, tannins, total phenol and flavonoids contents were closely associated with the resistance to whitefly. 4 The increases of three enzyme activity were in favor of the synthesis of secondary metabolites and the expression of resistance to greenhouse whitefly in glabrous cucumber, while the activities of three enzymes highly expressed in different leaves. POD activity in the first leaves of cucumber seedlings and in the down leaves of adult period was the highest, PAL、PPO activity in the third leaves of cucumber seedling and in up down leaves of adult period was the highest, content of tannin and lignin was higher in old leaves, content of total phenol and flavonoids was higher in the new leaves. It illustrated interaction relationships in the enzymes and the leaves. It also confirmed that plant leaves had signal response、transmission and interaction,which is a self-protection complex response system mechanism. The differences of secondary metabolites in glabrous cucumber leaves were a closely relationship with the resistance to whitefly.5 After greenhouse whitefly infestating the leaves, the changes of PAL, PPO, POD activity and the contents of tannin, lignin, total phenol and flavonoids in injured leaves and uninjured leaves were consistent, but the increments and the reductions in different leaves were significantly different. It was the performance of the overall resistance of the plant, which provided a scientific basis for sampling.

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CLC: > Agricultural Sciences > Plant Protection > Pest and Disease Control > Horticultural Crops Pest and Disease Control > Vegetable pests > Melons, pests and diseases > Cucumber pests and diseases
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