Sequencing and comparison of the Rickettsia genomes from the whitefly Bemisia tabaci Middle East Asia Minor I.
The whitefly, Bemisia tabaci, harbors the primary symbiont 'Candidatus Portiera aleyrodidarum' and a variety of secondary symbionts. Among these secondary symbionts, Rickettsia is the only one that can be detected both inside and outside the bacteriomes. Infection with Rickettsia has been reported to influence several aspects of the whitefly biology, such as fitness, sex ratio, virus transmission and resistance to pesticides. However, mechanisms underlying these differences remain unclear, largely due to the lack of genomic information of Rickettsia. In this study, we sequenced the genome of two Rickettsia strains isolated from the Middle East Asia Minor 1 (MEAM1) species of the B. tabaci complex in China and Israel. Both Rickettsia genomes were of high coding density and AT-rich, containing more than 1000 coding sequences, much larger than that of the coexisted primary symbiont, Portiera. Moreover, the two Rickettsia strains isolated from China and Israel shared most of the genes with 100% identity and only nine genes showed sequence differences. The phylogenetic analysis using orthologs shared in the genus, inferred the proximity of Rickettsia in MEAM1 and Rickettsia bellii. Functional analysis revealed that Rickettsia was unable to synthesize amino acids required for complementing the whitefly nutrition. Besides, a type IV secretion system and a number of virulence-related genes were detected in the Rickettsia genome. The presence of virulence-related genes might benefit the symbiotic life of the bacteria, and hint on potential effects of Rickettsia on whiteflies. The genome sequences of Rickettsia provided a basis for further understanding the function of Rickettsia in whiteflies.
Ministry of Agriculture Key Laboratory of Agricultural Entomology, Institute of Insect Sciences, Zhejiang University, Hangzhou, China.
Dan-Tong
DT
Zhu
Ministry of Agriculture Key Laboratory of Agricultural Entomology, Institute of Insect Sciences, Zhejiang University, Hangzhou, China.
Wen-Qiang
WQ
Xia
School of Agriculture and Food Science, Zhejiang Agriculture and Forestry University, Lin'an, Hangzhou, China.
Qiong
Q
Rao
Ministry of Agriculture Key Laboratory of Agricultural Entomology, Institute of Insect Sciences, Zhejiang University, Hangzhou, China.
Shu-Sheng
SS
Liu
Department of Entomology, Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel.
Murad
M
Ghanim
Ministry of Agriculture Key Laboratory of Agricultural Entomology, Institute of Insect Sciences, Zhejiang University, Hangzhou, China.
Xiao-Wei
XW
Wang
D000818:Animals; D002681:China; D004269:DNA, Bacterial / Q000235:genetics; D016680:Genome, Bacterial; D006430:Hemiptera / Q000382:microbiology*; D007557:Israel; D010802:Phylogeny; D012281:Rickettsia / Q000235:genetics*; D013045:Species Specificity; D013559:Symbiosis; D014774:Virulence / Q000235:genetics
D004269:DNA, Bacterial
Bemisia tabaci; Rickettsia; comparison; endosymbiont; genome; symbiosis