Análise de RNA-SEQ e RNA de interferência em formigas cortadeiras Atta sexdens

Abstract

Leaf-cutting ant Atta sexdens, also known as ‘saúva-limão’, are social insects considered important agricultural pests in Brazil. It is owing to its natural habit of cutting out fresh plant material for feeding its own symbiont fungus living inside the colony. Many researches have sought ways to control ant population by using methods less harmful to the environment and human beings. However, the most employed method has still been via application of toxic baits and other chemical insecticides widely known as dangerous. For the generation of effective technologies and products for the pest management, it is required to understand the ecological, biological, chemical and molecular aspects involving the species behavior. Taking it into account, the functional genomics era, also known as transcriptomics, comes as a valuable molecular and cellular biology research area of great relevance to overcome information gaps and to contribute to the resolution of several biological issues not understood yet. Accordingly, after obtaining the specific molecular resources from the species of interest, the transcriptomic profile analysis may be useful for identifying expressed genes in specific conditions and/or tissues, elucidating the dynamic of metabolic pathways and cooperating on the better understanding of the leaf-cutting ant lifestyle. Furthermore, such resources will be helpful in the search for target-directed molecular strategies for insect pest control. Currently, a growing biotechnological area which has been receiving more attention within the pest control sector is the RNA interference-mediated mechanism (RNAi). In this mechanism, double-stranded RNA (dsRNA) molecules homologous to target genes are provided to insects through body injection or feeding on a diet, or even through dsRNA-expressing transgenic plants, in order to induce the post-transcriptional gene silencing selectively and in a sequence-specific manner. In this context, the present work brings novel information about the transcriptomic profile of the leaf-cutting ant A. sexdens, revealing the presence of enzymes participating in the core RNAi machinery, besides opening doors for the prospection of potential target genes to be silenced in the species. Moreover, RNAi bioassays with worker ants targeting orthologous genes previously silenced in other species showed that the cell's response mechanism likely triggered the RNAi pathway activation, decreasing the mRNA levels of some target genes and inducing the insect mortality after exposure of ants fed on dsRNA-containing diets.