title: Genome reduction and potential metabolic complementation of the dual endosymbionts in the whitefly Bemisia tabaci.
abstract: BACKGROUND
  The whitefly Bemisia tabaci is an important agricultural pest with global distribution. This phloem-sap feeder harbors a primary symbiont, "Candidatus Portiera aleyrodidarum", which compensates for the deficient nutritional composition of its food sources, and a variety of secondary symbionts. Interestingly, all of these secondary symbionts are found in co-localization with the primary symbiont within the same bacteriocytes, which should favor the evolution of strong interactions between symbionts.
  
  
  RESULTS
  In this paper, we analyzed the genome sequences of the primary symbiont Portiera and of the secondary symbiont Hamiltonella in the B. tabaci Mediterranean (MED) species in order to gain insight into the metabolic role of each symbiont in the biology of their host. The genome sequences of the uncultured symbionts Portiera and Hamiltonella were obtained from one single bacteriocyte of MED B. tabaci. As already reported, the genome of Portiera is highly reduced (357 kb), but has kept a number of genes encoding most essential amino-acids and carotenoids. On the other hand, Portiera lacks almost all the genes involved in the synthesis of vitamins and cofactors. Moreover, some pathways are incomplete, notably those involved in the synthesis of some essential amino-acids. Interestingly, the genome of Hamiltonella revealed that this secondary symbiont can not only provide vitamins and cofactors, but also complete the missing steps of some of the pathways of Portiera. In addition, some critical amino-acid biosynthetic genes are missing in the two symbiotic genomes, but analysis of whitefly transcriptome suggests that the missing steps may be performed by the whitefly itself or its microbiota.
  
  
  CONCLUSIONS
  These data suggest that Portiera and Hamiltonella are not only complementary but could also be mutually dependent to provide a full complement of nutrients to their host. Altogether, these results illustrate how functional redundancies can lead to gene losses in the genomes of the different symbiotic partners, reinforcing their inter-dependency.
authors.affiliation: Ministry of Agriculture Key Laboratory of Agricultural Entomology, Institute of Insect Sciences, Zhejiang University, 310058, Hangzhou, China. qiong.rao@163.com.|School of Agriculture and Food Science, Zhejiang A & F University, 311300, Lin'an, Zhejiang, China. qiong.rao@163.com.
authors.forename: Qiong
authors.initials: Q
authors.lastname: Rao
authors.affiliation: Université de Lyon, Université Lyon1, Laboratoire de Biométrie et Biologie Evolutive, UMR CNRS 558, 69622, Villeurbanne, Cedex, France. pierre-antoine.farnier@univ-lyon1.fr.|Inria Grenoble Rhône-Alpes, Grenoble, France. pierre-antoine.farnier@univ-lyon1.fr.
authors.forename: Pierre-Antoine
authors.initials: PA
authors.lastname: Rollat-Farnier
authors.affiliation: Ministry of Agriculture Key Laboratory of Agricultural Entomology, Institute of Insect Sciences, Zhejiang University, 310058, Hangzhou, China. zjwzzdt@163.com.
authors.forename: Dan-Tong
authors.initials: DT
authors.lastname: Zhu
authors.affiliation: Institut Cavanilles de Biodiversitat i Biologia Evolutiva, Universitat de València, Valencia, Spain. Diego.Santos@uv.es.
authors.forename: Diego
authors.initials: D
authors.lastname: Santos-Garcia
authors.affiliation: Institut Cavanilles de Biodiversitat i Biologia Evolutiva, Universitat de València, Valencia, Spain. francisco.silva@uv.es.|Unidad Mixta de Investigación en Genómica y Salud FISABIO-Salud Pública and Universitat de València, Valencia, Spain. francisco.silva@uv.es.
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Silva
authors.affiliation: Institut Cavanilles de Biodiversitat i Biologia Evolutiva, Universitat de València, Valencia, Spain. Andres.Moya@uv.es.|Unidad Mixta de Investigación en Genómica y Salud FISABIO-Salud Pública and Universitat de València, Valencia, Spain. Andres.Moya@uv.es.
authors.forename: Andrés
authors.initials: A
authors.lastname: Moya
authors.affiliation: Institut Cavanilles de Biodiversitat i Biologia Evolutiva, Universitat de València, Valencia, Spain. amparo.latorre@uv.es.|Unidad Mixta de Investigación en Genómica y Salud FISABIO-Salud Pública and Universitat de València, Valencia, Spain. amparo.latorre@uv.es.
authors.forename: Amparo
authors.initials: A
authors.lastname: Latorre
authors.affiliation: Université de Lyon, Université Lyon1, Laboratoire de Biométrie et Biologie Evolutive, UMR CNRS 558, 69622, Villeurbanne, Cedex, France. Cecilia.Coimbra-Klein@univ-lyon1.fr.|Inria Grenoble Rhône-Alpes, Grenoble, France. Cecilia.Coimbra-Klein@univ-lyon1.fr.
authors.forename: Cecilia C
authors.initials: CC
authors.lastname: Klein
authors.affiliation: Université de Lyon, Université Lyon1, Laboratoire de Biométrie et Biologie Evolutive, UMR CNRS 558, 69622, Villeurbanne, Cedex, France. Fabrice.Vavre@univ-lyon1.fr.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Vavre
authors.affiliation: Université de Lyon, Université Lyon1, Laboratoire de Biométrie et Biologie Evolutive, UMR CNRS 558, 69622, Villeurbanne, Cedex, France. marie-france.sagot@inria.fr.|Inria Grenoble Rhône-Alpes, Grenoble, France. marie-france.sagot@inria.fr.
authors.forename: Marie-France
authors.initials: MF
authors.lastname: Sagot
authors.affiliation: Ministry of Agriculture Key Laboratory of Agricultural Entomology, Institute of Insect Sciences, Zhejiang University, 310058, Hangzhou, China. shshliu@zju.edu.cn.
authors.forename: Shu-Sheng
authors.initials: SS
authors.lastname: Liu
authors.affiliation: Université de Lyon, Université Lyon1, Laboratoire de Biométrie et Biologie Evolutive, UMR CNRS 558, 69622, Villeurbanne, Cedex, France. laurence.mouton@univ-lyon1.fr.
authors.forename: Laurence
authors.initials: L
authors.lastname: Mouton
authors.affiliation: Ministry of Agriculture Key Laboratory of Agricultural Entomology, Institute of Insect Sciences, Zhejiang University, 310058, Hangzhou, China. xwwang@zju.edu.cn.
authors.forename: Xiao-Wei
authors.initials: XW
authors.lastname: Wang
mesh_terms: D000596:Amino Acids / Q000096:biosynthesis; D000818:Animals; D004247:DNA / Q000032:analysis / Q000302:isolation & purification / Q000378:metabolism; D004755:Enterobacteriaceae / Q000235:genetics*; D016680:Genome, Bacterial; D044129:Halomonadaceae / Q000235:genetics*; D006430:Hemiptera / Q000235:genetics* / Q000378:metabolism / Q000382:microbiology*; D059014:High-Throughput Nucleotide Sequencing; D017404:In Situ Hybridization, Fluorescence; D053858:Metabolic Networks and Pathways / Q000235:genetics; D008969:Molecular Sequence Data; D017422:Sequence Analysis, DNA; D013559:Symbiosis / Q000235:genetics*; D014815:Vitamins / Q000096:biosynthesis
chemical_list: D000596:Amino Acids; D014815:Vitamins; D004247:DNA