Sclerotium rolfsii lectin exerts insecticidal activity on Spodoptera litura larvae by binding to membrane proteins of midgut epithelial cells and triggering caspase-3-dependent apoptosis

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• 作者：Vishwanathreddy H. ; Ganapati G. Bhat ; Shashikala R. Inamdar ; Ravindra K. Gudihal ; Bale M. Swamy
• 关键词：Toxicity ; Sclerotium rolfsii lectin (SRL) ; Spodoptera litura ; Gal/GalNAc-specific fungal lectin ; Apoptosis ; DNA fragmentation
• 刊名：Toxicon
• 出版年：February, 2014
• 年：2014
• 卷：78
• 期：Complete
• 页码：47-57
• 全文大小：1594 K

文摘

The insect pest Spodoptera litura is considered a major threat to many economically important food and commercial crops. The present study establishes the toxic effects of Sclerotium rolfsii lectin (SRL) against S. litura larvae fed an artificial diet containing the purified lectin. The toxicity of SRL, as determined by feeding assays using different concentrations of the lectin, showed marginal effects on larval growth but a remarkable mortality rate of 68.52聽卤聽8.48% at the highest lectin concentration, 0.06% (600聽渭g/g), with an LC₅₀ value of 430聽渭g/g of artificial diet. SRL is resistant to proteolysis by larval gut proteases even after 24-h聽incubation. Histochemical studies and western blot analyses of lectin binding revealed the interaction of the lectin with specific membrane glycoproteins on epithelial cells of the midgut. Identification of SRL-interacting midgut membrane proteins using lectin affinity chromatography and ESI-Q-TOF analysis revealed the involvement of these proteins in immunomodulatory responses in insects. Active caspase-3-like activity and DNA fragmentation observed in the midgut epithelial cells of larvae fed a lectin-containing diet supported the mechanism of apoptosis-induced death. These findings suggested that SRL can be a valuable tool in plant biotechnology for developing insect-resistant transgenic crops.