Plant–mediated horizontal transmission of Wolbachia between whiteflies

Abstract

Maternal transmission is the main transmission pathway of facultative bacterial endosymbionts, but phylogenetically distant insect hosts harbor closely related endosymbionts, suggesting that horizontal transmission occurs in nature. Here we report the first case of plant-mediated horizontal transmission of Wolbachia between infected and uninfected Bemisia tabaci AsiaII7 whiteflies. After infected whiteflies fed on cotton leaves, Wolbachia was visualized, both in the phloem vessels and in some novel ‘reservoir' spherules along the phloem by fluorescence in situ hybridization using Wolbachia-specific 16S rRNA probes and transmission electron microscopy. Wolbachia persisted in the plant leaves for at least 50 days. When the Wolbachia-free whiteflies fed on the infected plant leaves, the majority of them became infected with the symbiont and vertically transmitted it to their progeny. Multilocus sequence typing and sequencing of the wsp (Wolbachia surface protein) gene confirmed that the sequence type of Wolbachia in the donor whiteflies, cotton phloem and the recipient whiteflies are all identical (sequence type 388). These results were replicated using cowpea and cucumber plants, suggesting that horizontal transmission is also possible through other plant species. Our findings may help explain why Wolbachia bacteria are so abundant in arthropods, and suggest that in some species, Wolbachia may be maintained in populations by horizontal transmission.

An elusive endosymbiont: Does Wolbachia occur naturally in Aedes aegypti?

“…High Wolbachia densities in the ovaries are also consistent with a true infection, since maternal transmission requires infection of the germ line (Veneti, Clark, Karr, Savakis, & Bourtzis, ) but not somatic tissues, although Wolbachia often occupy somatic tissues (Dobson et al, ). Electron microscopy images show apparent localization of Wolbachia to the ovaries, but images are low resolution and there is no clear distinction between Wolbachia and organelles as in other recent studies (Leclercq et al, ; Li et al, ).…”

“…Although Wolbachia are maternally inherited, interspecific transfer may occur through parasitism (Ahmed et al, ; Heath, Butcher, Whitfield, & Hubbard, ), consumption of infected individuals (Le Clec'h et al, , Brown & Lloyd, ), sharing a common environment (Huigens, Almeida, Boons, Luck, & Stouthamer, ; Li et al, ), or other mechanisms. Successful horizontal transmission is likely to be rare, but Wolbachia can spread rapidly throughout populations once introduced (Kriesner, Hoffmann, Lee, Turelli, & Weeks, ; Turelli & Hoffmann, ).…”

Metacommunity theory for transmission of heritable symbionts within insect communities

“…Symbiont dispersal depends on two main factors: the ability to transmit from one host to the next and the ability to successfully establish within the new host. Symbionts can be transmitted vertically (parent to offspring) but also horizontally (between individuals or via the environment; Caspi‐Fluger et al, ; Haselkorn, Markow, & Moran, ; Hosokawa et al, ; Jaenike, ; Li et al, ).…”

Co‐occurrence of pederin‐producing and Wolbachia endobacteria in Paederus fuscipes Curtis, 1840 (Coleoptera: Staphilinidae) and its evolutionary consequences

“…Wolbachia , obligate endosymbionts, are estimated to infect 40% of terrestrial arthropod species (Zug & Hammerstein, ) and many parasitic filarial nematodes (Taylor, Bandi, & Hoerauf, ). They manipulate reproduction properties of the hosts through the induction of cytoplasmic incompatibility, parthenogenesis, feminization, and male killing (Hughes, Pamilo, & Kathirithamby, ; Li et al, ; Li, Wang, Bourguet, & He, ; Vavre, Fleury, Lepetit, Fouillet, & Boulétreau, ; Werren, ; Yun, Peng, Liu, & Lei, ).…”