title: Evidence of environmental and vertical transmission of Burkholderia symbionts in the oriental chinch bug, Cavelerius saccharivorus (Heteroptera: Blissidae).
abstract: The vertical transmission of symbiotic microorganisms is omnipresent in insects, while the evolutionary process remains totally unclear. The oriental chinch bug, Cavelerius saccharivorus (Heteroptera: Blissidae), is a serious sugarcane pest, in which symbiotic bacteria densely populate the lumen of the numerous tubule-like midgut crypts that the chinch bug develops. Cloning and sequence analyses of the 16S rRNA genes revealed that the crypts were dominated by a specific group of bacteria belonging to the genus Burkholderia of the Betaproteobacteria. The Burkholderia sequences were distributed into three distinct clades: the Burkholderia cepacia complex (BCC), the plant-associated beneficial and environmental (PBE) group, and the stinkbug-associated beneficial and environmental group (SBE). Diagnostic PCR revealed that only one of the three groups of Burkholderia was present in ∼89% of the chinch bug field populations tested, while infections with multiple Burkholderia groups within one insect were observed in only ∼10%. Deep sequencing of the 16S rRNA gene confirmed that the Burkholderia bacteria specifically colonized the crypts and were dominated by one of three Burkholderia groups. The lack of phylogenetic congruence between the symbiont and the host population strongly suggested host-symbiont promiscuity, which is probably caused by environmental acquisition of the symbionts by some hosts. Meanwhile, inspections of eggs and hatchlings by diagnostic PCR and egg surface sterilization demonstrated that almost 30% of the hatchlings vertically acquire symbiotic Burkholderia via symbiont-contaminated egg surfaces. The mixed strategy of symbiont transmission found in the oriental chinch bug might be an intermediate stage in evolution from environmental acquisition to strict vertical transmission in insects.
authors.affiliation: Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST) Hokkaido, Sapporo, Japan.
authors.forename: Hideomi
authors.initials: H
authors.lastname: Itoh
authors.affiliation: Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST) Hokkaido, Sapporo, Japan Graduate School of Life Science, Hokkaido University, Sapporo, Japan.
authors.forename: Manabu
authors.initials: M
authors.lastname: Aita
authors.affiliation: Okinawa Prefectural Agricultural Research Center, Itoman, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Nagayama
authors.affiliation: Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan.
authors.forename: Xian-Ying
authors.initials: XY
authors.lastname: Meng
authors.affiliation: Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST) Hokkaido, Sapporo, Japan.
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Kamagata
authors.affiliation: Research Institute for Environmental Management Technology, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan.
authors.forename: Ronald
authors.initials: R
authors.lastname: Navarro
authors.affiliation: Research Institute for Environmental Management Technology, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Hori
authors.affiliation: Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST) Hokkaido, Sapporo, Japan Graduate School of Life Science, Hokkaido University, Sapporo, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Ohgiya
authors.affiliation: Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST) Hokkaido, Sapporo, Japan y-kikuchi@aist.go.jp.
authors.forename: Yoshitomo
authors.initials: Y
authors.lastname: Kikuchi
mesh_terms: D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D019117:Burkholderia / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004064:Digestive System / Q000382:microbiology; D004777:Environment; D005260:Female; D020062:Heteroptera / Q000382:microbiology*; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012329:RNA, Bacterial / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013559:Symbiosis
chemical_list: D004269:DNA, Bacterial; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S