title: Silencing of the olfactory co-receptor gene in Dendroctonus armandi leads to EAG response declining to major host volatiles.
abstract: In this study, a polymerase chain reaction (PCR) based on homology genes of Orco was utilized to identify DarmOrco, which is essential for olfaction in D. armandi. The results showed that DarmOrco shares significant sequence homology with Orco proteins had known in other insects. Quantitative real-time PCR (qRT-PCR) analysis suggested that DarmOrco was abundantly expressed in adult D. armandi; by contrast, DarmOrco showed trace amounts of expression level in other stages. Of different tissues, DarmOrco expression level was the highest in the antennae. In order to understand the functional significance of Orco, we injected siRNA of DarmOrco into the conjunctivum between the second and third abdominal segments, and evaluated its expression after siRNA injected for 24 h, 48 h and 72 h. The results of qRT-PCR demonstrated that the reduction of mRNA expression level was significant (~80%) in DarmOrco siRNA-treated D. armandi than in water-injected and non-injected controls. The electroantennogram responses of females and males to 11 major volatiles of its host, were also reduced (30~68% for females; 16~70% for males) in siRNA-treated D. armandi compared with the controls. These results suggest that DarmOrco is crucial in mediating odorant perception.
authors.affiliation: College of Forestry, Northwest A&F University, Yangling, Shaanxi 712100, China.
authors.forename: Ranran
authors.initials: R
authors.lastname: Zhang
authors.affiliation: College of Forestry, Northwest A&F University, Yangling, Shaanxi 712100, China.
authors.forename: Guanqun
authors.initials: G
authors.lastname: Gao
authors.affiliation: College of Forestry, Northwest A&F University, Yangling, Shaanxi 712100, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Chen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D057506:Arthropod Antennae / Q000187:drug effects / Q000502:physiology; D001483:Base Sequence; D002630:Chemotactic Factors / Q000494:pharmacology; D017124:Conserved Sequence; D005260:Female; D015870:Gene Expression; D055785:Gene Knockdown Techniques; D019476:Insect Proteins / Q000235:genetics* / Q000378:metabolism; D008297:Male; D039821:Monoterpenes / Q000494:pharmacology; D009928:Organ Specificity; D010802:Phylogeny; D028223:Pinus / Q000737:chemistry; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D018035:Receptors, Odorant / Q000235:genetics* / Q000378:metabolism; D048889:Weevils / Q000235:genetics* / Q000378:metabolism
chemical_list: D002630:Chemotactic Factors; D019476:Insect Proteins; D039821:Monoterpenes; D034741:RNA, Small Interfering; D018035:Receptors, Odorant