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Characterization of a chitin synthase encoding gene and effect of diflubenzuron in soybean aphid Aphis glycines

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Chitin synthases are critical enzymes for synthesis of chitin and thus for subsequent growth and development in insects. We have identified and characterized a chitin synthase gene (CHS) from cDNA of Aphis glycines, the soybean aphid, a serious pest of soybean. The full-length cDNA of CHS in A. glycines (AyCHS) was 5802 bp long with an open reading frame of 4704 bp that encoded for a 1567 amino acid residues protein. The AyCHS protein had a molecular mass of 180.05 kDa and its amino acid sequence contained all the signature motifs (EDR, QRRRW and TWGTR) of chitin synthases. Real-time PCR analysis revealed that AyCHS was expressed in all major tissues (gut, fat body and integument), however, it had the highest expression in integument (~3.5 fold compared to gut). Interestingly, the expression of AyCHS in developing embryos was nearly 7 fold higher compared to adult integument, which probably is a reflection of embryonic molts in hemimetabolus insects. Expression analysis in different developmental stages of A. glycines revealed that AyCHS was expressed in all stages but had the highest expression in second instar stage. Further, through leaf dip bioassays, we tested the effect of diflubenzuron(DFB, Dimilin®), a chitin-synthesis inhibitor, on A. glycines’ survival, fecundity and body weight. When fed with soybean leaves previously dipped in 50 ppm diflubenzuron solution, A. glycines nymphs suffered significantly higher mortality as compared to control. A. glycines nymphs feeding on diflubenzuron treated leaves also showed significantly enhanced expression (~1.7 fold) of AyCHS compared to nymphs on untreated leaves. The current study provides a platform to develop novel strategies to manage this pest using chitin-synthesis inhibitors and using RNAi by knocking down AyCHS expression.
Raman Bansal , M. A. Rouf Mian , Omprakash Mittapalli , Andy P. Michel
Aphis glycines , Glycine max , RNA interference , adults , amino acid sequences , bioassays , body weight , chitin , chitin synthase , complementary DNA , diflubenzuron , digestive system , embryo (animal) , enzyme inhibitors , fat body , fecundity , gene expression , genes , insect control , insect pests , instars , integument , leaves , molecular weight , molting , mortality , nymphs , open reading frames , quantitative polymerase chain reaction , soybeans
International journal of biological sciences 2012 v.8 no.10
Journal Articles, USDA Authors, Peer-Reviewed
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