This Article Full Text Full Text (PDF) Supplemental material Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kikuchi, Y. Articles by Fukatsu, T. Search for Related Content PubMed PubMed Citation Articles by Kikuchi, Y. Articles by Fukatsu, T. Agricola Articles by Kikuchi, Y. Articles by Fukatsu, T.

 Previous Article  |  Next Article 

Applied and Environmental Microbiology, July 2007, p. 4308-4316, Vol. 73, No. 13
0099-2240/07/$08.00+0     doi:10.1128/AEM.00067-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Insect-Microbe Mutualism without Vertical Transmission: a Stinkbug Acquires a Beneficial Gut Symbiont from the Environment Every Generation ^,

Yoshitomo Kikuchi,^1,2* Takahiro Hosokawa,¹ and Takema Fukatsu¹

Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8566, Japan,¹ Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut 06269-3125²

Received 11 January 2007/ Accepted 24 April 2007

The broad-headed bug Riptortus clavatus (Heteroptera: Alydidae) possesses a number of crypts at a posterior midgut region, which house a dense population of a bacterial symbiont belonging to the genus Burkholderia. Although the symbiont is highly prevalent (95 to 100%) in the host populations, the symbiont phylogeny did not reflect the host systematics at all. In order to understand the mechanisms underlying the promiscuous host-symbiont relationship despite the specific and prevalent association, we investigated the transmission mode and the fitness effects of the Burkholderia symbiont in R. clavatus. Inspection of eggs and a series of rearing experiments revealed that the symbiont is not vertically transmitted but is environmentally acquired by nymphal insects. The Burkholderia symbiont was present in the soil of the insect habitat, and a culture strain of the symbiont was successfully isolated from the insect midgut. Rearing experiments by using sterilized soybean bottles demonstrated that the cultured symbiont is able to establish a normal and efficient infection in the host insect, and the symbiont infection significantly improves the host fitness. These results indicated that R. clavatus postnatally acquires symbiont of a beneficial nature from the environment every generation, uncovering a previously unknown pathway through which a highly specific insect-microbe association is maintained. We suggest that the stinkbug-Burkholderia relationship may be regarded as an insect analogue of the well-known symbioses between plants and soil-associated microbes, such as legume-Rhizobium and alder-Frankia relationships, and we discuss the evolutionary relevance of the mutualistic but promiscuous insect-microbe association.

---

* Corresponding author. Mailing address: Department of Molecular and Cell Biology, University of Connecticut, 91 N. Eagleville Rd., Unit-3125, Storrs, CT 06269-3125. Phone: (860) 486-2104. Fax: (860) 486-4331. E-mail: yoshitomo.kikuchi{at}uconn.edu

Published ahead of print on 4 May 2007.

Supplemental material for this article may be found at http://aem.asm.org/.

---

Applied and Environmental Microbiology, July 2007, p. 4308-4316, Vol. 73, No. 13
0099-2240/07/$08.00+0     doi:10.1128/AEM.00067-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

This article has been cited by other articles:

• Benitez, M.-S., McSpadden Gardener, B. B. (2009). Linking Sequence to Function in Soil Bacteria: Sequence-Directed Isolation of Novel Bacteria Contributing to Soilborne Plant Disease Suppression. Appl. Environ. Microbiol. 75: 915-924 [Abstract] [Full Text]