Insect transmitted plant pathogenic mollicutes, Spiroplasma kunkelii and aster yellows witches' broom phytoplasma: from structural genomics to functional genomics
Year: 2004
Type: article
Abstract: The mollicutes, Spiroplasma kunkelii and aster yellows witches' broom (AY-WB) phytoplasma, are insect-transmitted plant pathogens.These mollicutes invade and replicate in cells of various insect organs and tissues, and inhabit and replicate in plant phloem tissues.They cause severe symptoms to many plant species worldwide, including economically important crops and ornamental plants.Their fastidious nature and lack of genetic tools have hampered the research on these plant pathogenic mollicutes.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 partial genome of S. kunkelii and the complete genome of AY-WB phytoplasma were sequenced.Genome annotation revealed the presence of multiple spiroplasma phage DNA sequences in S. kunkelii and many repetitive elements in both genomes, suggestive of frequent recombination events.The genome sequence data provide genetic basis for the study of the biology and pathogenicity mechanisms of these organisms.Whereas spiroplasmas and phytoplasmas are distantly related to each other, they share the plant and insect habitats.Therefore, they may share genes involved in insect localization study with the yellow fluorescent protein fusions of these two proteins revealed their localization in the plant nuclei and confirmed their dependence on plant importin α for nuclear transport.Transcripts corresponding to the phytoplasma proteins were detected in AY-WB phytoplasma-infected insects and plants by RT-PCR.Microarrays demonstrated that phytoplasma A11 protein affected the expression profiles of 53 tomato genes, including several transcription factors, indicating that phytoplasma A11 protein directly or indirectly interacts with these proteins.These data are supportive of the hypothesis that A11 is a bona fide effector protein involved in plant pathogenicity.In summary, the research described in this dissertation resulted in the identification of several mollicute genes that are potentially involved in insect transmission and plant pathogenicity.It demonstrated that the genome sequencing, comparative genomics, and functional genomics approaches allow efficient identification and characterization of such genes in bacterial genomes.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, and molecular and diagnosis/detection tools are available.The described research and approaches might be useful for other pathogenic mollicutes that are recalcitrant to in vitro manipulation, detection and characterization, including the economically important mycoplasmas that impact human health and livestock industries.
Author: Xiaodong Bai
Institution: The Ohio State University
Language: English
Subfield: Plant Science
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2517420854