RESUMO
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.
Assuntos
Quitinases/genética , Resistência à Doença/genética , Proteínas de Insetos/genética , Doenças das Plantas/genética , Spodoptera/genética , Zea mays/genética , Animais , Western Blotting , Quitinases/metabolismo , Gossypium/parasitologia , Interações Hospedeiro-Parasita , Proteínas de Insetos/metabolismo , Insetos/fisiologia , Mariposas/fisiologia , Controle Biológico de Vetores/métodos , Doenças das Plantas/parasitologia , Folhas de Planta/parasitologia , Plantas Geneticamente Modificadas , Reprodutibilidade dos Testes , Spodoptera/enzimologia , Spodoptera/fisiologia , Zea mays/parasitologiaRESUMO
BACKGROUND: Wheat is considered the most important cereal crop all over the world. The wheat weevil Sitophilus granarius is a serious insect pests in much of the wheat growing area worldwide and is responsible for significant loss of yield. Avidin proteins has been proposed to function as plant defense agents against insect pests. RESULTS: A synthetic avidin gene was introduced into spring wheat (Triticum aestivum L.) cv. Giza 168 using a biolistic bombardment protocol. The presence and expression of the transgene in six selected T0 transgenic wheat lines were confirmed at the molecular level. Accumulation of avidin protein was detected in transgenic plants compared to non-transgenic plants. Avidin transgene was stably integrated, transcribed and translated as indicated by Southern blot, ELISA, and dot blot analyses, with a high level of expression in transgenic wheat seeds. However, no expression was detected in untransformed wheat seeds. Functional integrity of avidin was confirmed by insect bioassay. The results of bioassay using transgenic wheat plants challenged with wheat weevil revealed 100 % mortality of the insects reared on transgenic plants after 21 days. CONCLUSION: Transgenic wheat plants had improved resistance to Sitophilus granarius.
