title: Knockdown of the corazonin gene reveals its critical role in the control of gregarious characteristics in the desert locust.
abstract: The two plague locusts, Schistocerca gregaria and Locusta migratoria, exhibit density-dependent phase polyphenism. Nymphs occurring at low population densities (solitarious forms) are uniformly colored and match their body color to the background color of their habitat, whereas those occurring at high population densities (gregarious) develop black patterns. An injection of the neuropeptide, corazonin (Crz) has been shown to induce black patterns in locusts and affect the classical morphometric ratio, F/C (F, hind femur length; C, maximum head width). We herein identified and cloned the CRZ genes from S. gregaria (SgCRZ) and L. migratoria. A comparative analysis of prepro-Crz sequences among insects showed that the functional peptide was well conserved; its conservation was limited to the peptide region. Silencing of the identified SgCRZ gene in gregarious S. gregaria nymphs markedly lightened their body color and shifted the adult F/C ratio toward the value typical of solitarious forms. In addition, knockdown of the gene in solitarious nymphs strongly inhibited darkening even after a transfer to crowded conditions; however, these individuals developed black patterns after being injected with the Crz as a rescue treatment. SgCRZ was constitutively expressed in the brains of S. gregaria during nymphal development in both phases. This gene was highly expressed not only in the brain in both phases, but also in the corpora allata in the gregarious phase. This conspicuous phase-dependent difference in SgCRZ gene expression may indicate a functional role in the control of phase polyphenism in this locust.
authors.affiliation: Insect Growth Regulation Research Unit, National Institute of Agrobiological Sciences, 1-2 Owashi, Tsukuba, Ibaraki 305-8634, Japan.
authors.forename: Ryohei
authors.initials: R
authors.lastname: Sugahara
authors.affiliation: Locust Research Laboratory, National Institute of Agrobiological Sciences, 1-2 Owashi, Tsukuba, Ibaraki 305-8634, Japan; Graduate School of Agricultural Science, Kobe University, 657-8501, Japan.
authors.forename: Shinjiro
authors.initials: S
authors.lastname: Saeki
authors.affiliation: Insect Genome Research Unit, National Institute of Agrobiological Sciences, 1-2 Owashi, Tsukuba, Ibaraki 305-8634, Japan.
authors.forename: Akiya
authors.initials: A
authors.lastname: Jouraku
authors.affiliation: Insect Growth Regulation Research Unit, National Institute of Agrobiological Sciences, 1-2 Owashi, Tsukuba, Ibaraki 305-8634, Japan. Electronic address: shiotsuk@affrc.go.jp.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Shiotsuki
authors.affiliation: Locust Research Laboratory, National Institute of Agrobiological Sciences, 1-2 Owashi, Tsukuba, Ibaraki 305-8634, Japan. Electronic address: stanaka@affrc.go.jp.
authors.forename: Seiji
authors.initials: S
authors.lastname: Tanaka
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D018507:Gene Expression Regulation, Developmental; D055785:Gene Knockdown Techniques; D006110:Grasshoppers / Q000033:anatomy & histology / Q000235:genetics* / Q000378:metabolism; D019476:Insect Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009479:Neuropeptides / Q000235:genetics* / Q000378:metabolism; D009758:Nymph / Q000378:metabolism; D010858:Pigmentation / Q000235:genetics; D013045:Species Specificity
chemical_list: D019476:Insect Proteins; D009479:Neuropeptides; C060602:corazonin protein, insect
keywords: Corazonin; Desert locust; Gene expression; Migratory locust; Phase polyphenism; RNAi