454 pyrosequencing based transcriptome analysis of Zygaena filipendulae with focus on genes involved in biosynthesis of cyanogenic glucosides

Linamarin and lotaustralin are aliphatic cyanogenic glucosides widespread in plants and also found in many insects. Moths belonging to the Zygaena family are the only known insects able to carry out de novo biosynthesis of the cyanogenic glucosides and to sequester them from their food plants as well. Upon cleavage by beta-glucosidases, cyanogenic glucosides release hydrogen cyanide and thereby provide protection against predators. Female Z. filipendulae moths also prefer males with a high content of cyanogenic glucosides and the chosen male transfer cyanogenic glucosides to her during mating. The biosynthetic pathway for cyanogenic glucoside biosynthesis in the Z. filipendulae moth proceeds using the same intermediates as in plants, but none of the genes or enzymes responsible have been identified in the moth. A genomics strategy founded on 454 pyrosequencing of the Z. filipendulae transcriptome was undertaken to identify some of these genes in Z. filipendulae. Comparisons of the Z. filipendulae transcriptome with the sequenced genomes of Bombyx mori and Drosophila melanogaster indicate a high coverage of the Z. filipendulae transcriptome. The Z. filipendulae transcriptome was also compared to known sequences from cyanogenic Heliconius butterflies. This work demonstrated that pyrosequencing is an attractive approach to gain access to genes in the biosynthesis of bio-active natural products from e.g. insects for which the genome sequence is not known. Based on analysis of the Z. filipendulae transcriptome, promising gene candidates for biosynthesis of cyanogenic glucosides have been identified. The suitability of Z. filipendulae as a model system for cyanogenesis in insects is evident.