title: Redox states of plastids and mitochondria differentially regulate intercellular transport via plasmodesmata.
abstract: Recent studies suggest that intercellular transport via plasmodesmata (PD) is regulated by cellular redox state. Until now, this relationship has been unclear, as increased production of reactive oxygen species (ROS) has been associated with both increased and decreased intercellular transport via PD. Here, we show that silencing two genes that both increase transport via PD, INCREASED SIZE EXCLUSION LIMIT1 (ISE1) and ISE2, alters organelle redox state. Using redox-sensitive green fluorescent proteins targeted to the mitochondria or plastids, we show that, relative to wild-type leaves, plastids are more reduced in both ISE1- and ISE2-silenced leaves, whereas mitochondria are more oxidized in ISE1-silenced leaves. We further show that PD transport is positively regulated by ROS production in mitochondria following treatment with salicylhydroxamic acid but negatively regulated by an oxidative shift in both chloroplasts and mitochondria following treatment with paraquat. Thus, oxidative shifts in the mitochondrial redox state positively regulate intercellular transport in leaves, but oxidative shifts in the plastid redox state counteract this effect and negatively regulate intercellular transport. This proposed model reconciles previous contradictory evidence relating ROS production to PD transport and supports accumulating evidence that mitochondria and plastids are crucial regulators of PD function.
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, USA.
authors.forename: Solomon
authors.initials: S
authors.lastname: Stonebloom
authors.forename: Jacob O
authors.initials: JO
authors.lastname: Brunkard
authors.forename: Alexander C
authors.initials: AC
authors.lastname: Cheung
authors.forename: Keni
authors.initials: K
authors.lastname: Jiang
authors.forename: Lewis
authors.initials: L
authors.lastname: Feldman
authors.forename: Patricia
authors.initials: P
authors.lastname: Zambryski
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D001692:Biological Transport / Q000187:drug effects; D002736:Chloroplasts / Q000378:metabolism; D053487:DEAD-box RNA Helicases / Q000235:genetics / Q000378:metabolism; D020868:Gene Silencing; D008928:Mitochondria / Q000378:metabolism*; D010084:Oxidation-Reduction; D010269:Paraquat / Q000494:pharmacology; D018515:Plant Leaves / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D031425:Plasmodesmata / Q000378:metabolism*; D018087:Plastids / Q000378:metabolism*; D020365:RNA Helicases / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D012457:Salicylamides / Q000494:pharmacology
chemical_list: D029681:Arabidopsis Proteins; D017382:Reactive Oxygen Species; D012457:Salicylamides; C005703:salicylhydroxamic acid; C523445:INCREASED SIZE EXCLUSION LIMIT2 protein, Arabidopsis; C552345:Ise1 protein, Arabidopsis; D053487:DEAD-box RNA Helicases; D020365:RNA Helicases; D010269:Paraquat
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