title: A complex of genes involved in adaptation of Leptinotarsa decemlineata larvae to induced potato defense.
abstract: The Colorado potato beetle (Leptinotarsa decemlineata) is the most important pest of potato in many areas of the world. One of the main reasons for its success lies in the ability of its larvae to counteract plant defense compounds. Larvae adapt to protease inhibitors (PIs) produced in potato leaves through substitution of inhibitor-sensitive digestive cysteine proteases with inhibitor-insensitive cysteine proteases. To get a broader insight into the basis of larval adaptation to plant defenses, we created a "suppression subtractive hybridisation" library using cDNA from the gut of L. decemlineata larvae fed methyl jasmonate-induced or uninduced potato leaves. Four hundred clones, randomly selected from the library, were screened for their relevance to adaptation with DNA microarray hybridizations. Selected enzyme systems of beetle digestion were further inspected for changes in gene expression using quantitative PCR and enzyme activity measurements. We identified two new groups of digestive cysteine proteases, intestains D and intestains E. Intestains D represent a group of structurally distinct digestive cysteine proteases, of which the tested members are strongly upregulated in response to induced plant defenses. Moreover, we found that other digestive enzymes also participate in adaptation, namely, cellulases, serine proteases, and an endopolygalacturonase. In addition, juvenile hormone binding protein-like (JHBP-like) genes were upregulated. All studied genes were expressed specifically in larval guts. In contrast to earlier studies that reported experiments based on PI-enriched artificial diets, our results increase understanding of insect adaptation under natural conditions.
authors.affiliation: Department of Biotechnology and Systems Biology, National Institute of Biology, Ljubljana, Slovenia. marko.petek@nib.si
authors.forename: Marko
authors.initials: M
authors.lastname: Petek
authors.forename: Neža
authors.initials: N
authors.lastname: Turnšek
authors.forename: Meti Buh
authors.initials: MB
authors.lastname: Gašparič
authors.forename: Maruša Pompe
authors.initials: MP
authors.lastname: Novak
authors.forename: Kristina
authors.initials: K
authors.lastname: Gruden
authors.forename: Nina
authors.initials: N
authors.lastname: Slapar
authors.forename: Tatjana
authors.initials: T
authors.lastname: Popovič
authors.forename: Borut
authors.initials: B
authors.lastname: Štrukelj
authors.forename: Kristina
authors.initials: K
authors.lastname: Gruden
authors.forename: Borut
authors.initials: B
authors.lastname: Štrukelj
authors.forename: Maarten A
authors.initials: MA
authors.lastname: Jongsma
mesh_terms: D000222:Adaptation, Physiological; D000595:Amino Acid Sequence; D000818:Animals; D002480:Cellulase / Q000235:genetics; D002918:Chymotrypsin / Q000235:genetics / Q000378:metabolism; D001517:Coleoptera / Q000235:genetics* / Q000378:metabolism; D023082:Defensins / Q000235:genetics; D041981:Gastrointestinal Tract / Q000378:metabolism; D015870:Gene Expression; D049750:Genome, Insect; D006790:Host-Parasite Interactions; D019476:Insect Proteins / Q000235:genetics*; D007814:Larva / Q000502:physiology; D008969:Molecular Sequence Data; D011096:Polygalacturonase / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D011198:Solanum tuberosum / Q000469:parasitology*
chemical_list: D023082:Defensins; D019476:Insect Proteins; D011096:Polygalacturonase; D002480:Cellulase; D002918:Chymotrypsin