The morphology and spatiotemporal dynamics of the Rickettsia endosymbiont transmitted by the whitefly Bemisia tabaci to host plants
Author of the article:SHI Pei-Qiong XIE Li-Zhu XU Jin LIU Yuan QIU Bao-Li
Author's Workplace:College of Coastal Agricultural Sciences, Guangdong Ocean University, Zhanjiang 524088, China; Key Laboratory of Bio-pesticide Innovation and Application, Guangzhou 510640, China; Engineering Technology Research Center of Agricultural Pest Biocontrol of Guangdong Province, Guangzhou 510640, China
Key Words:Bemisia tabaci; endosymbiont; Rickettsia; horizontal transmission; insect host; plant host
Abstract:
[Objectives] To detect endosymbiont species transmitted to
plants by the feeding behavior of the whitefly Bemisia tabaci, and the morphology and
spatiotemporal dynamics of Rickettsia in different host plants. [Methods] The transmission of endosymbionts by the B. tabaci B biotype into cotton, tomato
and cowpea plants was investigated. Endosymbionts were detected by PCR and the
location and morphology of Rickettsia in plants observed with TEM. Dynamic changes in Rickettsia titers in cowpea leaves was detected with q-PCR. [Results] The B.
tabaci B biotype is infected with the obligate endosymbiont Portiera and the facultative
endosymbionts Rickettsia, Hamiltonella and Hemipteriphilus. Only Rickettsia was transmitted to cotton, tomato and cowpea plants by B. tabaci feeding activity. Rickettsia can move between different plant leaves and TEM revealed that it is located in the sieve tube cells of
plant phloem. The morphology of Rickettsia in B. tabaci, cotton and tomato
leaves was similar, but it was relatively smaller and slight rounder in cowpea
leaves. The titers of Rickettsia in
cowpea plants first increased, then decreased, with increased duration of
continuous feeding by B. tabaci.
However, in cowpea plants that had been fed on by whiteflies for only 7 days it
first decreased, then increased slightly, then remained basically unchanged.
Phylogenetic analysis based on variation in the 16S rDNA sequence indicates
that Rickettsia found in cotton,
tomato and cowpea leaves is identical to Rickettsia in B. tabaci. [Conclusion] Rickettsia can be transmitted to host
plants by the feeding activity of B.
tabaci after which it becomes localized in the sieve tube cells of phloem
and can move between different leaves. The morphology of Rickettsia may vary slightly in different hosts, and the efficiency
of transmission of Rickettsia varies
with host plant species.