Identification of translocatable RNA‐binding phloem proteins from melon, potential components of the long‐distance RNA transport system

Gómez, Gustavo; Torres, Héctor N.; Pallás, Vicente

doi:10.1111/j.1365-313x.2004.02278.x

Cited by 141 publications

(96 citation statements)

References 50 publications

(91 reference statements)

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“…As the phloem sap has been demonstrated to contain a range of mRNA species and RNA binding proteins Xoconostle-Cá zares et al, 1999;Yoo et al, 2004;Gomez et al, 2005), some of which appear to influence events taking place in the meristem (Kim et al, 2001;Haywood et al, 2005), the possibility exists that FT mRNA could act as the signaling molecule. Lifschitz et al (2006) conducted a series of heterografting studies to test this possibility.…”

Section: Introductionmentioning

confidence: 99%

FLOWERING LOCUS T Protein May Act as the Long-Distance Florigenic Signal in the Cucurbits

Bélanger²,

et al. 2007

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Cucurbita moschata, a cucurbit species responsive to inductive short-day (SD) photoperiods, and Zucchini yellow mosaic virus (ZYMV) were used to test whether long-distance movement of FLOWERING LOCUS T (FT) mRNA or FT is required for floral induction. Ectopic expression of FT by ZYMV was highly effective in mediating floral induction of long-day (LD)-treated plants. Moreover, the infection zone of ZYMV was far removed from floral meristems, suggesting that FT transcripts do not function as the florigenic signal in this system. Heterografting demonstrated efficient transmission of a florigenic signal from flowering Cucurbita maxima stocks to LD-grown C. moschata scions. Real-time RT-PCR performed on phloem sap collected from C. maxima stocks detected no FT transcripts, whereas mass spectrometry of phloem sap proteins revealed the presence of Cm-FTL1 and Cm-FTL2. Importantly, studies on LD-and SD-treated C. moschata plants established that Cmo-FTL1 and Cmo-FTL2 are regulated by photoperiod at the level of movement into the phloem and not by transcription. Finally, mass spectrometry of florally induced heterografted C. moschata scions revealed that C. maxima FT, but not FT mRNA, crossed the graft union in the phloem translocation stream. Collectively, these studies are consistent with FT functioning as a component of the florigenic signaling system in the cucurbits.

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Section: Introductionmentioning

confidence: 99%

FLOWERING LOCUS T Protein May Act as the Long-Distance Florigenic Signal in the Cucurbits

Bélanger²,

et al. 2007

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“…Hence, numerous transcription factors have functions that are spatially distinct from their sites of synthesis (Lucas et al, 1995;Gallagher et al, 2004;Kim et al, 2005;Kurata et al, 2005), and small RNA species involved in RNA silencing move symplastically from cell to cell (Yoo et al, 2004;Gomez et al, 2005). Pds are channels that traverse the cell wall to establish a symplastic continuum through most of the plant.…”

Section: Introductionmentioning

confidence: 99%

AnArabidopsisGPI-Anchor Plasmodesmal Neck Protein with Callose Binding Activity and Potential to Regulate Cell-to-Cell Trafficking

et al. 2009

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Plasmodesmata (Pds) traverse the cell wall to establish a symplastic continuum through most of the plant. Rapid and reversible deposition of callose in the cell wall surrounding the Pd apertures is proposed to provide a regulatory process through physical constriction of the symplastic channel. We identified members within a larger family of X8 domaincontaining proteins that targeted to Pds. This subgroup of proteins contains signal sequences for a glycosylphosphatidylinositol linkage to the extracellular face of the plasma membrane. We focused our attention on three closely related members of this family, two of which specifically bind to 1,3-b-glucans (callose) in vitro. We named this family of proteins Pd callose binding proteins (PDCBs). Yellow fluorescent protein-PDCB1 was found to localize to the neck region of Pds with potential to provide a structural anchor between the plasma membrane component of Pds and the cell wall. PDCB1, PDCB2, and PDCB3 had overlapping and widespread patterns of expression, but neither single nor combined insertional mutants for PDCB2 and PDCB3 showed any visible phenotype. However, increased expression of PDCB1 led to an increase in callose accumulation and a reduction of green fluorescent protein (GFP) movement in a GFP diffusion assay, identifying a potential association between PDCB-mediated callose deposition and plant cell-to-cell communication.

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“…In Cucurbita maxima, the P-proteins are the two most abundant sap proteins: Phloem Protein1 (PP1), which belongs to a gene family found only in cucurbits (Clark et al, 1997), and PP2, which belongs to a large gene family in angiosperms (Bostwick et al, 1992(Bostwick et al, , 1994Dinant et al, 2003). In cucurbits, PP2s display additional properties, including RNA binding Pallás, 2001, 2004;Owens et al, 2001;Gó mez et al, 2005), trafficking from cell to cell, and modification of the size exclusion limit of the plasmodesmata (Balachandran et al, 1997). These observations suggest that PP2 might play a role in the cell-to-cell trafficking of macromolecules.…”

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confidence: 99%

Binding Properties of the N-Acetylglucosamine and High-Mannose N-Glycan PP2-A1 Phloem Lectin in Arabidopsis

et al. 2010

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Phloem Protein2 (PP2) is a component of the phloem protein bodies found in sieve elements. We describe here the lectin properties of the Arabidopsis (Arabidopsis thaliana) PP2-A1. Using a recombinant protein produced in Escherichia coli, we demonstrated binding to N-acetylglucosamine oligomers. Glycan array screening showed that PP2-A1 also bound to highmannose N-glycans and 9-acyl-N-acetylneuraminic sialic acid. Fluorescence spectroscopy-based titration experiments revealed that PP2-A1 had two classes of binding site for N,N#,N$-triacetylchitotriose, a low-affinity site and a high-affinity site, promoting the formation of protein dimers. A search for structural similarities revealed that PP2-A1 aligned with the Cbm4 and Cbm22-2 carbohydrate-binding modules, leading to the prediction of a b-strand structure for its conserved domain. We investigated whether PP2-A1 interacted with phloem sap glycoproteins by first characterizing abundant Arabidopsis phloem sap proteins by liquid chromatography-tandem mass spectrometry. Then we demonstrated that PP2-A1 bound to several phloem sap proteins and that this binding was not completely abolished by glycosidase treatment. As many plant lectins have insecticidal activity, we also assessed the effect of PP2-A1 on weight gain and survival in aphids. Unlike other mannosebinding lectins, when added to an artificial diet, recombinant PP2-A1 had no insecticidal properties against Acyrthosiphon pisum and Myzus persicae. However, at mid-range concentrations, the protein affected weight gain in insect nymphs. These results indicate the presence in PP2-A1 of several carbohydrate-binding sites, with potentially different functions in the trafficking of endogenous proteins or in interactions with phloem-feeding insects.

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Identification of translocatable RNA‐binding phloem proteins from melon, potential components of the long‐distance RNA transport system

Cited by 141 publications

References 50 publications

FLOWERING LOCUS T Protein May Act as the Long-Distance Florigenic Signal in the Cucurbits

FLOWERING LOCUS T Protein May Act as the Long-Distance Florigenic Signal in the Cucurbits

AnArabidopsisGPI-Anchor Plasmodesmal Neck Protein with Callose Binding Activity and Potential to Regulate Cell-to-Cell Trafficking

Binding Properties of the N-Acetylglucosamine and High-Mannose N-Glycan PP2-A1 Phloem Lectin in Arabidopsis

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