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Insect transmitted plant pathogenic mollicutes, Spiroplasma kunkelii and aster yellows witches' broom phytoplasma: from structural genomics to functional genomics

Bai, Xiaodong
http://rave.ohiolink.edu/etdc/view?acc_num=osu1101752677

Abstract Details

2004, Doctor of Philosophy, Ohio State University, Entomology.
I employed various approaches, including genome sequencing, comparative genomics, functional genomics, and conventional molecular techniques, to study the biology and pathogenicity mechanisms of S. kunkelii and AY-WB phytoplasma. The economically important insect-transmitted plant pathogenic mollicutes, Spiroplasma kunkelii and aster yellows witches' broom (AY-WB) phytoplasma, invade and replicate in various insect tissue cells, and inhabit and replicate in plant phloem tissues. The partial genome of S. kunkelii and the complete genome of AY-WB phytoplasma were sequenced. The genome sequence data provide genetic basis for the study of the biology and pathogenicity mechanisms of these organisms. Comparative genome analysis among mollicutes was conducted, and resulted in the identification of four genes that are present in the genomes of all plant-pathogenic mollicutes sequenced so far, but missing from the mycoplasmas. Another gene within both genomes might have been derived by horizontal gene transfer between spiroplasmas and phytoplasmas. Four traE gene homologs were identified as membrane-bound ATPases in S. kunkelii M2 strain and are possibly involved in spiroplasma conjugation and adhesion. The AY-WB phytoplasma genome sequences were mined for potentially secreted proteins that may directly interact with host cell components and hence are candidate effector proteins. High-throughput functional assays resulted in the identification of 17 candidate effector proteins. Plant localization studies with the YFP fusions of two NLS-containing proteins (A11 and A30) revealed their localization in the plant nuclei and confirmed the dependence of A11 on plant importin a proteins for nuclear import. Transcripts corresponding to the phytoplasma proteins were detected in AY-WB phytoplasma-infected insects and plants. Microarrays demonstrated that phytoplasma A11 protein could affect the expression of 53 tomato genes, supporting the hypothesis that A11 is an effector protein involved in plant pathogenicity. The importance of the research lies in the application of high throughput bioinformatics, genomics and molecular approaches in the study of agriculturally important organisms for which little information is available. The described research and approaches might be useful for other pathogenic mollicutes that are recalcitrant to in vitro manipulation, including the economically important mycoplasmas that impact human health and livestock industries.
Saskia Hogenhout (Advisor)
232 p.
Biology, Entomology
PHYTOPLASMA; SPIROPLASMA; KUNKELII; AY-WB; proteins; genome; MOLLICUTES

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Citations

  • Bai, X. (2004). Insect transmitted plant pathogenic mollicutes, Spiroplasma kunkelii and aster yellows witches' broom phytoplasma: from structural genomics to functional genomics [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1101752677

    APA Style (7th edition)

  • Bai, Xiaodong. Insect transmitted plant pathogenic mollicutes, Spiroplasma kunkelii and aster yellows witches' broom phytoplasma: from structural genomics to functional genomics. 2004. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1101752677.

    MLA Style (8th edition)

  • Bai, Xiaodong. "Insect transmitted plant pathogenic mollicutes, Spiroplasma kunkelii and aster yellows witches' broom phytoplasma: from structural genomics to functional genomics." Doctoral dissertation, Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=osu1101752677

    Chicago Manual of Style (17th edition)

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This open access ETD is published by The Ohio State University and OhioLINK.