Transcriptome analysis of host-specific interactions in natural populations of the cotton bollworm (Helicoverpa armigera)

André Ricardo Oliveira Conson1, Natália Faraj Murad1, Rogerio Martins Gonçalves1, Karina Lucas Silva-Brand?o2, Fernando Luis Cônsoli3, Celso Omoto3, Marcelo Mendes Brandão1

1 Center of Molecular Biology and Genetic Engineering, University of Campinas, Campinas, Brazil
2 Federal university of ABC, Centre for Natural Sciences and Humanities, Santo André, Brazil
3 Department of Entomology and Acarology, College of Agriculture “Luiz de Queiroz”, University of são Paulo, Piracicaba, Brazil

One of the most important lepidopteran pests worldwide is the noctuid Helicoverpa armigera. The generalist feeding habit of the species is of great interest for agriculture since the cultivation of different annual crops may provide ideal conditions for survival and set of new populations. Since its introduction in South America, H. armigera has infested a wide range of hosts whereas knowledge about enzymes responsible for the digestive and detoxification processes are still scarce, specially under natural conditions. Thus, to develop efficient controlling methods of this pest, it is mandatory first to determine which genes are involved in its plant interactions and their expression levels. In the present study, H. armigera larvae from natural populations were sampled in order to investigate its transcriptome pattern toward different host plants. Larvae were sampled from soybean (Glycine max (L.) Merr), cotton (Gossypium hirsutum L.), bean (Phaseolus vulgaris (L.)), pearl millet (Pennisetum glaucum (L.)), maize (Zea mays L.) and grain sorghum (Sorghum bicolor (L) Moench). A transcriptome de novo assembly resulted in 132,378 transcripts, and 65,947 were successfully annotated. Host conditions in H. armigera revealed 43 differentially expressed transcripts. The largest number was obtained in comparison between soybean and bean, resulting in 27 down-regulated and seven up-regulated transcripts in soybean. A set of differentially expressed transcripts specifically associated with cotton and bean were identified. Functional analysis showed that genes involved in electron transport chain are implicated in host responses. We also visualized expression patterns in important gene families, including serine proteases and intracellular lipid-binding proteins. This study of H. armigera transcriptome provided a set of candidate transcripts that demonstrates host-insect interactions on natural conditions.

Key-words: Noctuidae, polyphagous, RNA-seq, digestive enzymes, gene expression


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