title: Sequence similarity and functional comparisons of pheromone receptor orthologs in two closely related Helicoverpa species.
abstract: The olfactory system of moth species in subfamily Heliothinae is an attractive model to study the evolution of the pheromone reception because they show distinct differentiation in sex pheromone components or ratios that activate pheromone receptors (PRs). However, functional assessment of PRs in closely related species remains largely untried. Here we present a special cloning strategy to isolate full-length cDNAs encoding candidate odorant receptors (ORs) from Helicoverpa armigera (Harm) and Helicoverpa assulta (Hass) on the basis of Heliothis virescens ORs, and investigate the functional properties of PRs to determine how the evolution of moth PRs contribute to intraspecific mating choice and speciation extension. We cloned 11 OR orthologs from H. armigera and 10 from H. assulta. We functionally characterized the responses of PRs of both species to seven pheromone compounds using the heterologous expression system of Xenopus ooctyes. HassOR13 was found to be highly tuned to the sex pheromone component Z11-16:Ald, and unexpectedly, both HarmOR14b and HassOR16 were specific for Z9-14:Ald. However, HarmOR6 and HassOR6 showed much higher specificity to Z9-16:OH than to Z9-16:Ald or Z9-14:Ald. HarmOR11, HarmOR14a, HassOR11 and HassOR14b failed to respond to the tested chemicals. Based on our results and previous research, we can show that some PR orthologs from H. armigera, H. assulta and H. virescens such as OR13s have similar ligand selectivity, but others have different ligand specificity. The combined PR function and sex pheromone component analysis suggests that the evolution of PRs can meet species-specific demands.
authors.affiliation: State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang District, Beijing, China; Shandong Peanut Research Institute, Qingdao, China.
authors.forename: Xiao-Jing
authors.initials: XJ
authors.lastname: Jiang
authors.affiliation: State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang District, Beijing, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Guo
authors.affiliation: State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang District, Beijing, China.
authors.forename: Chang
authors.initials: C
authors.lastname: Di
authors.affiliation: Shandong Peanut Research Institute, Qingdao, China.
authors.forename: Shanlin
authors.initials: S
authors.lastname: Yu
authors.affiliation: Shandong Peanut Research Institute, Qingdao, China.
authors.forename: Ligui
authors.initials: L
authors.lastname: Zhu
authors.affiliation: State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang District, Beijing, China.
authors.forename: Ling-Qiao
authors.initials: LQ
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang District, Beijing, China. Electronic address: czwang@ioz.ac.cn.
authors.forename: Chen-Zhu
authors.initials: CZ
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D057506:Arthropod Antennae; D055724:Electrophysiological Phenomena; D015870:Gene Expression; D049810:Genetic Speciation; D009036:Moths / Q000235:genetics*; D043563:Receptors, Pheromone / Q000235:genetics* / Q000378:metabolism*; D060047:Reproductive Isolation; D012724:Sex Attractants; D012903:Smell
chemical_list: D043563:Receptors, Pheromone; D012724:Sex Attractants
keywords: Functional evolution; Helicoverpa armigera; Helicoverpa assulta; Odorant receptor; Pheromone receptor