Abstract
Due to the importance of chitinolytic enzymes for insect, nematode and fungal growth, they are receiving attention concerning their development as biopesticides or chemical defense proteins in transgenic plants and as microbial biocontrol agents. Targeting chitin associated with the extracellular matrices or cell wall by insect chitinases may be an effective approach for controlling pest insects and pathogenic fungi. The ability of chitinases to attack and digest chitin in the peritrophic matrix or exoskeleton raises the possibility to use them as insect control method. In this study, an insect chitinase cDNA from cotton leaf worm (Spodoptera littoralis) has been synthesized. Transgenic maize plant system was used to improve its tolerance against insects. Insect chitinase transcripts and proteins were expressed in transgenic maize plants. The functional integrity and expression of chitinase in progenies of the transgenic plants were confirmed by insect bioassays. The bioassays using transgenic corn plants against corn borer (Sesamia cretica) revealed that ~50% of the insects reared on transgenic corn plants died, suggesting that transgenic maize plants have enhanced resistance against S. cretica.
Highlights
Due to the importance of chitinolytic enzymes for insect, nematode and fungal growth, they are receiving attention concerning their development as biopesticides or chemical defense proteins in transgenic plants and as microbial biocontrol agents
Synthesis and sequencing of a cDNA encoding an insect chitinase from cotton leaf worm: For cloning the insect chitinase cDNA, RT-PCR was performed using one pair of specific primers based on Spodoptera frugiperda[25] chitinase gene (ChF1and ChR1) and total RNA isolated from the integuments of third instar larvae as described in the Materials and Methods section
Transgenic plants expressing an insect chitinase gene have shown enhanced resistance to insect feeding in many studies
Summary
Due to the importance of chitinolytic enzymes for insect, nematode and fungal growth, they are receiving attention concerning their development as biopesticides or chemical defense proteins in transgenic plants and as microbial biocontrol agents. Chitinases are being used to perturb structures containing chitin such as cuticle and peritrophic matrix (PM) that are essential for growth, development and survival of insects[7,8]. Chitinases are among a group of proteins that insects use to digest the structural polysaccharide chitin in www.nature.com/scientificreports/. Their exoskeletons and gut linings during the molting process[14]. Larvae of C. fumiferana died more rapidly when exposed to chitinase–Bt mixtures than when exposed to the enzyme or bacterium alone[20,21] These studies have shown that insect chitinases, which belong to family 18 glycosylhydrolases, are good alternative for insect control
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