Regulation of Solute Flux through Plasmodesmata in the Root Meristem

Rutschow, Heidi L.; Baskin, Tobias I.; Kramer, Eric M.

doi:10.1104/pp.110.168187

Cited by 113 publications

(135 citation statements)

References 30 publications

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“…Besides site of production, a recent, elegant study measuring changes in permeability of Arabidopsis roots (Rutschow et al, 2011) supports that ROS quantity regulates PD function. After only 2 h of treatment, application of low concentrations of H 2 O 2 (0.6 mM) to root tips increases PD permeability, but application of high concentrations of H 2 O 2 (6 mM) to root tips nearly abolished PD permeability.…”

Section: Discussionmentioning

confidence: 94%

Redox States of Plastids and Mitochondria Differentially Regulate Intercellular Transport via Plasmodesmata

et al. 2012

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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.

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Section: Discussionmentioning

confidence: 94%

Redox States of Plastids and Mitochondria Differentially Regulate Intercellular Transport via Plasmodesmata

et al. 2012

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“…This change in symplasmic coupling may reflect an effect of PDGLP1/2 OX on PD density. Alternatively, elevated levels of PDGLP1 or PDGLP2 could cause an increase in PD SEL, which could then have an effect on solute movement within the root (Rutschow et al, 2011). Phloem translocation into the Arabidopsis root system was examined by applying CFDA (60 µg/mL) onto a single cotyledon of 8-d-old seedlings.…”

Section: Formation Of Protein Complexes In Pd Is a Key Requirement Fomentioning

confidence: 99%

Overexpression of Arabidopsis Plasmodesmata Germin-Like Proteins Disrupts Root Growth and Development

Ham

Kang

et al. 2012

The Plant Cell

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In plants, a population of non-cell-autonomous proteins (NCAPs), including numerous transcription factors, move cell to cell through plasmodesmata (PD). In many cases, the intercellular trafficking of these NCAPs is regulated by their interaction with specific PD components. To gain further insight into the functions of this NCAP pathway, coimmunoprecipitation experiments were performed on a tobacco (Nicotiana tabacum) plasmodesmal-enriched cell wall protein preparation using as bait the NCAP, pumpkin (Cucurbita maxima) PHLOEM PROTEIN16 (Cm-PP16). A Cm-PP16 interaction partner, Nt-PLASMODESMAL GERMIN-LIKE PROTEIN1 (Nt-PDGLP1) was identified and shown to be a PD-located component. Arabidopsis thaliana putative orthologs, PDGLP1 and PDGLP2, were identified; expression studies indicated that, postgermination, these proteins were preferentially expressed in the root system. The PDGLP1 signal peptide was shown to function in localization to the PD by a novel mechanism involving the endoplasmic reticulum-Golgi secretory pathway. Overexpression of various tagged versions altered root meristem function, leading to reduced primary root but enhanced lateral root growth. This effect on root growth was corrected with an inability of these chimeric proteins to form stable PD-localized complexes. PDGLP1 and PDGLP2 appear to be involved in regulating primary root growth by controlling phloem-mediated allocation of resources between the primary and lateral root meristems.

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“…Microinjection of tracer molecules into a target cell (Terry and Robards, 1987;Tucker et al, 1989;Goodwin et al, 1990;Ding et al, 1992;Duckett et al, 1994) and fluorescence recovery after photobleaching (FRAP) experiments with preloaded tracers (Pina et al, 2009;Rutschow et al, 2011) were used not only to test if neighboring cells are symplasmically connected but also to quantify coupling. Recently, three-dimensional photoactivation of the tracer fluorescein bis-(5-carboxymethoxy-2-nitrobenzyl) ether (caged fluorescein) was used to quantify plasmodesmata-mediated cell wall permeability between Cucurbita maxima leaf mesophyll cells (MCs; .…”

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confidence: 99%

In Vivo Quantification of Cell Coupling in Plants with Different Phloem-Loading Strategies

Liesche

Schulz

2012

Plant Physiology

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Uptake of photoassimilates into the leaf phloem is the key step in carbon partitioning and phloem transport. Symplasmic and apoplasmic loading strategies have been defined in different plant taxa based on the abundance of plasmodesmata between mesophyll and phloem. For apoplasmic loading to occur, an absence of plasmodesmata is a sufficient but not a necessary criterion, as passage of molecules through plasmodesmata might well be blocked or restricted. Here, we present a noninvasive, whole-plant approach to test symplasmic coupling and quantify the intercellular flux of small molecules using photoactivation microscopy. Quantification of coupling between all cells along the prephloem pathways of the apoplasmic loader Vicia faba and Nicotiana tabacum showed, to our knowledge for the first time in vivo, that small solutes like sucrose can diffuse through plasmodesmata up to the phloem sieve element companion cell complex (SECCC). As expected, the SECCC was found to be symplasmically isolated for small solutes. In contrast, the prephloem pathway of the symplasmic loader Cucurbita maxima was found to be well coupled with the SECCC. Phloem loading in gymnosperms is not well understood, due to a profoundly different leaf anatomy and a scarcity of molecular data compared with angiosperms. A cell-coupling analysis for Pinus sylvestris showed high symplasmic coupling along the entire prephloem pathway, comprising at least seven cell border interfaces between mesophyll and sieve elements. Cell coupling together with measurements of leaf sap osmolality indicate a passive symplasmic loading type. Similarities and differences of this loading type with that of angiosperm trees are discussed.

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Regulation of Solute Flux through Plasmodesmata in the Root Meristem

Cited by 113 publications

References 30 publications

Redox States of Plastids and Mitochondria Differentially Regulate Intercellular Transport via Plasmodesmata

Redox States of Plastids and Mitochondria Differentially Regulate Intercellular Transport via Plasmodesmata

Overexpression of Arabidopsis Plasmodesmata Germin-Like Proteins Disrupts Root Growth and Development

In Vivo Quantification of Cell Coupling in Plants with Different Phloem-Loading Strategies

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