title: Dramatic transcriptional changes in an intracellular parasite enable host switching between plant and insect.
abstract: Phytoplasmas are bacterial plant pathogens that have devastating effects on the yields of crops and plants worldwide. They are intracellular parasites of both plants and insects, and are spread among plants by insects. How phytoplasmas can adapt to two diverse environments is of considerable interest; however, the mechanisms enabling the "host switching" between plant and insect hosts are poorly understood. Here, we report that phytoplasmas dramatically alter their gene expression in response to "host switching" between plant and insect. We performed a detailed characterization of the dramatic change that occurs in the gene expression profile of Candidatus Phytoplasma asteris OY-M strain (approximately 33% of the genes change) upon host switching between plant and insect. The phytoplasma may use transporters, secreted proteins, and metabolic enzymes in a host-specific manner. As phytoplasmas reside within the host cell, the proteins secreted from phytoplasmas are thought to play crucial roles in the interplay between phytoplasmas and host cells. Our microarray analysis revealed that the expression of the gene encoding the secreted protein PAM486 was highly upregulated in the plant host, which is also observed by immunohistochemical analysis, suggesting that this protein functions mainly when the phytoplasma grows in the plant host. Additionally, phytoplasma growth in planta was partially suppressed by an inhibitor of the MscL osmotic channel that is highly expressed in the plant host, suggesting that the osmotic channel might play an important role in survival in the plant host. These results also suggest that the elucidation of "host switching" mechanism may contribute to the development of novel pest controls.
authors.affiliation: Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.
authors.forename: Kenro
authors.initials: K
authors.lastname: Oshima
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Ishii
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Kakizawa
authors.forename: Kyoko
authors.initials: K
authors.lastname: Sugawara
authors.forename: Yutaro
authors.initials: Y
authors.lastname: Neriya
authors.forename: Misako
authors.initials: M
authors.lastname: Himeno
authors.forename: Nami
authors.initials: N
authors.lastname: Minato
authors.forename: Chihiro
authors.initials: C
authors.lastname: Miura
authors.forename: Takuya
authors.initials: T
authors.lastname: Shiraishi
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Yamaji
authors.forename: Shigetou
authors.initials: S
authors.lastname: Namba
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D002876:Chromosomes, Bacterial / Q000235:genetics; D004270:DNA, Circular / Q000235:genetics; D005682:Gadolinium / Q000494:pharmacology; D020869:Gene Expression Profiling / Q000379:methods; D015964:Gene Expression Regulation, Bacterial; D016680:Genome, Bacterial / Q000235:genetics; D058507:Host Specificity; D007150:Immunohistochemistry; D007313:Insecta / Q000382:microbiology*; D042541:Intracellular Space / Q000382:microbiology; D007473:Ion Channels / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D053858:Metabolic Networks and Pathways / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D009995:Osmosis; D045582:Phytoplasma / Q000235:genetics* / Q000378:metabolism; D010935:Plant Diseases / Q000382:microbiology; D010944:Plants / Q000382:microbiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D059467:Transcriptome
chemical_list: D001426:Bacterial Proteins; D004270:DNA, Circular; D007473:Ion Channels; D005682:Gadolinium; C038958:gadolinium chloride