Induction of the activities of antioxidative enzymes and the levels of malondialdehyde in cucumber seedlings as a consequence of Bemisia tabaci (Hemiptera: Aleyrodidae) infestation

Abstract

The activities of antioxidative enzymes and the concentration of malondialdehyde were assayed in cucumber leaves (Cucumis sativus L.) 0, 6, 12, 24, 48, 72, and 96 h after the cucumber seedlings were infested by Bemisia tabaci (Gennadius). The results indicated that the activities of antioxidative enzymes were increased after herbivore infestation, including superoxide dismutase (SOD), and peroxidase (POD), and the levels of malondialdehyde (MDA), which is a product of membrane lipid peroxidation in the leaves. The enzymes and MDA showed peaks of different activity levels at 24 and 48 h after the infestation. SOD activity reached the highest peak, 10.4% higher than control, at 24 h, POD activity reached the highest peak, 213.2% higher than control, at 6 h, catalase (CAT) activity was not statistically significant compared with the control, and MDA content reached the highest peak, 59.9% higher than control, at 48 h. The results suggested that the enhanced activities of antioxidative enzymes and MDA content may contribute to bioprotection of cucumber plants against B. tabaci infestation.

Herbivore- and Elicitor- Induced Resistance in Groundnut to Asian armyworm,Spodoptera litura(Fab.) (Lepidoptera: Noctuidae)

“…5,6 Polyphenol oxidase is an important secondary metabolism enzyme, whose role in bio-protection of plants against insects has been well established. [17][18][19] Pretreatment with JA prior to the insect infestation showed greater induction of both POD and PPO activities in groundnut plants followed by JA + and SIN + JA throughout the test period as compared with NCAc 343 and TMV 2.…”

Mechanisms of plant defense against insect herbivores

“…The PPOs are metallo-enzymes that catalyze the oxidation of monophenols and o-diphenols to quinones, which are highly reactive intermediate compounds that readily polymerize, and react with nucleophilic side chain of amino acids and crosslink proteins, thereby reducing the availability of such proteins, and affect the nutritional quality of the food. 34,83 Under acidic conditions, quinones form semiquinone radicals that in turn give rise to ROS, while under basic conditions; quinines react with cellular nucleophiles. 34 Quinines are more toxic to plant herbivores than the original phenols.…”

“…5,6,55 Production of phenoxy and other oxidative radicals by the PODs in association with phenols directly deter the feeding by insects and/or produces toxins that reduce the plant digestibility, which in turn leads to nutrient deficiency in insects with drastic effects on their growth and development. 57,83 In addition, PODs have been reported to have direct toxicity in guts of herbivores. 78 PODs have been purified and characterized from many plants where they were induced in response to insect attack.…”

“…4,5,125 JA is derived from linolenic acid through octadecanoid pathway and accumulates upon wounding and herbivory in plant tissues. 83 Chewing of plant parts by insects causes the dioxygenation of linoleic acid (18:2) and linolenic acid (18:3) by specific LOXs at C9 or C13 to form (9S)-or (13S)-hydroperoxy-octadecadi(tri)enoic acids, which are converted into 12-oxophytodienoic acid (12-OPDA) by allene oxide synthase and allene oxide cyclase. OPDA is transferred to the peroxisome, where it is reduced by OPDA reductase 3 (OPR3), forming JA.…”

The role of rice aldo/keto reductases in the detoxification of reactive carbonyls and their use to create stress resistant transgenic plants

“…-1 in Arabidopsis (Weber et al 2004), between 10-16 nmol (g fresh weight) -1 in cucumber (Zhang et al 2008) and 40-250 nmol (g fresh weight) -1 for olive leaves and pea leaves (Iturbe-Ormaetxe et al 1998, Sofo et al 2004). In the case of cucumber the range is dependent whether it is non-stressed condition (10 nmol) or pathogen infestation (up to 16 nmol).…”