Expression Chitinase gene and analysis of synergism between toxins of Bacillus thuringiensis in the control of Spodoptera frugiperda

Abstract

Chitinases (EC 3.2.1.14) are enzymes that degrade chitin, the second most abundant organic compound in nature, present in many organisms such as bacteria, fungi, plants and insects. In the search for alternative methods to control agricultural pests in order to reduce problems caused by the use of pesticides to the environment, humans and declining crop yields, the chitinases have been used successfully in combination with insecticides Vip and Cry proteins , produced by gram-positive bacterium Bacillus thuringiensis. The chitinase acts by increasing the insecticidal activity by perforating the peritrophic membrane of the midgut larvae and thus increasing the accessibility of these proteins to the receptors in the membranes of epithelial cells in pathogen. The use of bioenseticidas made to the base B. thuringiensis has shown satisfactory results against insects order Lepidoptera as such Spodoptera frugiperda (Smith, 1797) also known as the fall armyworm, which is the major pest of corn in Brazil. The present work aims to isolation, sequencing and gene expression of chitinase (chi) of an isolate of B. thuringiensis, and analysis of possible synergism between the chitinolytic activity and VIP3 proteins Cry1 and the control of Spodoptera frugiperda, and can then determine if the isolates will be effective as an bioinsecticide, or a source of genes for constructing maize plants pirâmidadas, over a transgene, decreasing the chances of insects becoming resistant.