Mechanisms of macroevolution: polyphagous plasticity in butterfly larvae revealed by RNA‐Seq

Abstract

Transcriptome studies of insect herbivory are still rare, yet studies in model systems have uncovered patterns of transcript regulation that appear to provide insights into how insect herbivores attain polyphagy, such as a general increase in expression breadth and regulation of ribosomal, digestion-and detoxification-related genes. We investigated the potential generality of these emerging patterns, in the Swedish comma, Polygonia c-album, which is a polyphagous, widely-distributed butterfly. Urtica dioica and Ribes uva-crispa are hosts of P. c-album, but Ribes represents a recent evolutionary shift onto a very divergent host. Utilizing the assembled transcriptome for read mapping, we assessed gene expression finding that caterpillar life-history (i.e. 2nd vs. 4th-instar regulation) had a limited influence on gene expression plasticity. In contrast, differential expression in response to host-plant identified genes encoding serine-type endopeptidases, membrane-associated proteins and transporters. Differential regulation of genes involved in nucleic acid binding was also observed suggesting that polyphagy involves large scale transcriptional changes. Additionally, transcripts coding for structural constituents of the cuticle were differentially expressed in caterpillars in response to their diet indicating that the insect cuticle may be a target for plant defence. Our results state that emerging patterns of transcript regulation from model species appear relevant in species when placed in an evolutionary context.

Gene expression plasticity across hosts of an invasive scale insect species

“…The recent spate of comparative transcriptomics studies indicates that broad diets are, in fact, facilitated by differential expression of detoxification genes [8, 16, 17]. However, those studies also indicate that detoxification genes are only a small part of the picture.…”

The retardant effect of 2-Tridecanone, mediated by Cytochrome P450, on the Development of Cotton bollworm, Helicoverpa armigera

“…Insects employ various strategies to increase their performance and fitness, while plants also develop efficient strategies to defend against particular insects [3]. Host plants can produce various allelochemicals to defend against the damage of herbivorous insects [4–6]. Plant allelochemicals possess beneficial or detrimental effects on the target pests; allelochemicals with negative allelopathic effects are an important part of plant defense against herbivory [7, 8].…”

“…These compounds can influence the growth, survival, and reproduction of other organisms. For example, the phenolic aldehyde gossypol can retard the developmental of the cotton bollworm, Helicoverpa armigera ( H. armigera ) [6]. The resistance of wild tomato ( Lycopersicon hirsutum f. glabratum ) to several arthropods has been shown to be related to the presence of high contencentrations of 2-tridecanone (2-TD) in leaves [5, 9].…”

“…Insect pests have evolved various strategies with which to respond to allelochemicals from host plants [6]. Cytochrome P450 enzymes are a major source of adaptation to plant defense mechanisms in insects [11, 12].…”

Characterization of Leaf Transcriptome in Banksia Hookeriana

“…RNA-seq technology provides ultra high-throughput sequencing data at an affordable cost, and has opened a door for new analyses in multiple research fields including population genetics and ecological adaptation [20]. In this study, we successfully sequenced transcriptomes of 4 B. hookeriana samples from different populations.…”