title: Fine-scale analysis of parasite resistance genes in the red flour beetle, Tribolium castaneum.
abstract: Parasite infection impacts population dynamics through effects on fitness and fecundity of the individual host. In addition to the known roles of environmental factors, host susceptibility to parasites has a genetic basis that has not been well characterized. We previously mapped quantitative trait loci (QTL) for susceptibility to rat tapeworm (Hymenolepis diminuta) infection in Tribolium castaneum using dominant AFLP markers; however, the resistance genes were not identified. Here, we refined the QTL locations and increased the marker density in the QTL regions using new microsatellite markers, sequence-tagged site markers, and single-strand conformational polymorphism markers. Resistance QTL in three linkage groups (LG3, LG6, and LG8) were each mapped to intervals <1.0 cM between two codominant markers. The effects of 21 genes in the three QTL regions were investigated by using quantitative RT-PCR analysis, and transcription profiles were obtained from the resistant TIW1 and the susceptible cSM strains. Based on transcription data, eight genes were selected for RNA interference analysis to investigate their possible roles in H. diminuta resistance, including cytochrome P450 (LOC657454) and Toll-like receptor 13 (TLR13, LOC662131). The transcription of P450 and TLR13 genes in the resistant TIW1 strains was reduced more than ninefold relative to the control. Moreover, the effects of gene knockdown of P450 and TLR13 caused resistant beetles to become susceptible to tapeworm infection, which strongly suggests an important role for each in T. castaneum resistance to H. diminuta infection.
authors.affiliation: Program in Public Health, College of Health Sciences, University of California, Irvine, California 92697.
authors.forename: Daibin
authors.initials: D
authors.lastname: Zhong
authors.forename: Aditi
authors.initials: A
authors.lastname: Pai
authors.forename: Mei-Hui
authors.initials: MH
authors.lastname: Wang
authors.forename: Naomi
authors.initials: N
authors.lastname: Keech
authors.forename: Guiyun
authors.initials: G
authors.lastname: Yan
mesh_terms: D000818:Animals; D002874:Chromosome Mapping; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism; D060467:Disease Resistance / Q000235:genetics*; D017344:Genes, Insect; D006925:Hymenolepiasis / Q000235:genetics / Q000276:immunology*; D048190:Hymenolepis diminuta / Q000472:pathogenicity; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism; D018895:Microsatellite Repeats; D018807:Polymorphism, Single-Stranded Conformational; D040641:Quantitative Trait Loci; D051193:Toll-Like Receptors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D014231:Tribolium / Q000235:genetics* / Q000469:parasitology
chemical_list: D019476:Insect Proteins; D051193:Toll-Like Receptors; D003577:Cytochrome P-450 Enzyme System
keywords: Hymenolepis diminuta; Tribolium castaneum; high-resolution mapping; parasite resistance gene; quantitative trait loci