Transcriptome analysis reveals candidate genes involved in luciferin metabolism inLuciola aquatilis(Coleoptera: Lampyridae)

Abstract

Bioluminescence, which living organisms such as fireflies emit light, has been studied extensively for over half a century. This intriguing reaction, having its origins in nature where glowing insects can signal things such as attraction or defense, is now widely used in biotechnology with applications of bioluminescence and chemiluminescence. Luciferase, a key enzyme in this reaction, has been well characterized; however, the enzymes involved in the biosynthetic pathway of its substrate, luciferin, remains unsolved at present. To elucidate the luciferin metabolism, we performed ade novotranscriptome analysis using larvae of the firefly species,Luciola aquatilis. Here, a comparative analysis is performed with the model coleopteran insectTribolium casteneumto elucidate the metabolic pathways inL. aquatilis. Based on a template luciferin biosynthetic pathway, combined with a range of protein and pathway databases, and various prediction tools for functional annotation, the candidate genes, enzymes, and biochemical reactions involved in luciferin metabolism are proposed forL. aquatilis. The candidate gene expression is validated in the adultL. aquatilisusing reverse transcription PCR (RT-PCR). This study provides useful information on the bio-production of luciferin in the firefly and will benefit to future applications of the valuable firefly bioluminescence system.