Plasma membrane localization of the type I H+-PPase AVP1 in sieve element–companion cell complexes from Arabidopsis thaliana

Páez-Valencia, Julio; Patrón‐Soberano, Araceli; Rodríguez-Leviz, Alejandra; Sanchez-Lares, Jonathan; Sánchez‐Gómez, Concepción; Valencia-Mayoral, Pedro; Diaz-Rosas, Guadalupe; Gaxiola, Roberto A.

doi:10.1016/j.plantsci.2011.03.008

Cited by 54 publications

(57 citation statements)

References 47 publications

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“…Importantly, AVP1 immunogold labeling in these plants showed normal PM localization in SE-CC complexes, which has been reported previously in Arabidopsis ( Fig. 6E; Paez-Valencia et al, 2011).…”

Section: Discussionsupporting

confidence: 89%

“…PM localization of AVP1 in SE-CC complexes has been extensively documented (Long et al, 1995;Ratajczak et al, 1999;Langhans et al, 2001;Paez-Valencia et al, 2011). Notably, overexpression of AVP1 and type I Figure 4.…”

Section: Discussionmentioning

confidence: 91%

“…Given the localization of H + -PPases at the PM of SE-CC complexes (Langhans et al, 2001;Paez-Valencia et al, 2011), the reversibility of the plant enzyme (Rocha Facanha and de Meis, 1998;Marsh et al, 2000), the thermodynamic constraints of PP i hydrolysis coupled to proton transport (Davies, 1997), and the key role of PP i in companion cells (Lerchl et al, 1995), a model was recently proposed , in which the PM-localized H + -PPase can function as a synthase in the phloem to maintain PP i homeostasis for the Suc oxidation and ATP production required for the generation of the PMF through PM H + -ATPase activity. As a corollary, increased PP i synthase activity in companion cells would augment phloem loading and long-distance transport in transgenic plants by indirectly energizing the SE-CC complex of source leaves.…”

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confidence: 99%

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Arabidopsis Type I Proton-Pumping Pyrophosphatase Expresses Strongly in Phloem, Where It Is Required for Pyrophosphate Metabolism and Photosynthate Partitioning

Pizzio

Páez-Valencia²,

Khadilkar³

et al. 2015

Plant Physiol.

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105

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Phloem loading is a critical process in plant physiology. The potential of regulating the translocation of photoassimilates from source to sink tissues represents an opportunity to increase crop yield. Pyrophosphate homeostasis is crucial for normal phloem function in apoplasmic loaders. The involvement of Arabidopsis (Arabidopsis thaliana) type I proton-pumping pyrophosphatase (AVP1) in phloem loading was analyzed at genetic, histochemical, and physiological levels. A transcriptional AVP1 promoter:: GUS fusion revealed phloem activity in source leaves. Ubiquitous AVP1 overexpression (35S::AVP1 cassette) enhanced shoot biomass, photoassimilate production and transport, rhizosphere acidification, and expression of sugar-induced root ion transporter genes (POTASSIUM TRANSPORTER2 By contrast, phloem-specific AVP1 knockdown (pCoYMV:: RNAi AVP1) resulted in stunted seedlings in sucrose-deprived medium. We also present a promoter mutant avp1-2 (SALK046492) with a 70% reduction of expression that did not show severe growth impairment. Interestingly, AVP1 protein in this mutant is prominent in the phloem. Moreover, expression of an Escherichia colisoluble pyrophosphatase in the phloem (pCoYMV::pyrophosphatase) of avp1-2 plants resulted in severe dwarf phenotype and abnormal leaf morphology. We conclude that the Proton-Pumping Pyrophosphatase AVP1 localized at the plasma membrane of the sieve element-companion cell complexes functions as a synthase, and that this activity is critical for the maintenance of pyrophosphate homeostasis required for phloem function.[

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Section: Discussionsupporting

confidence: 89%

Section: Discussionmentioning

confidence: 91%

mentioning

confidence: 99%

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Arabidopsis Type I Proton-Pumping Pyrophosphatase Expresses Strongly in Phloem, Where It Is Required for Pyrophosphate Metabolism and Photosynthate Partitioning

Pizzio

Páez-Valencia²,

Khadilkar³

et al. 2015

Plant Physiol.

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105

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“…Further, the high expression of IbVP1 in young storage root indicates an important function related to storage root development (Figure 2). These results further confirmed that up‐regulation of H + ‐PPase promoted translocation of photosynthates from leaf to root, as hypothesized previously (Gaxiola et al ., 2012; Hermans et al ., 2006; Khadilkar et al ., 2016; Paez‐Valencia et al ., 2011). A recent study also demonstrated that increased sucrose accumulation was required for the regulation of auxin‐mediated Fe deficiency in plants (Lin et al ., 2016).…”

Section: Discussionmentioning

confidence: 99%

H⁺‐pyrophosphatase IbVP1 promotes efficient iron use in sweet potato [Ipomoea batatas (L.) Lam.]

Fan

Wang

et al. 2017

Plant Biotechnology Journal

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SummaryIron (Fe) deficiency is one of the most common micronutrient deficiencies limiting crop production globally, especially in arid regions because of decreased availability of iron in alkaline soils. Sweet potato [Ipomoea batatas (L.) Lam.] grows well in arid regions and is tolerant to Fe deficiency. Here, we report that the transcription of type I H+‐pyrophosphatase (H+‐PPase) gene IbVP1 in sweet potato plants was strongly induced by Fe deficiency and auxin in hydroponics, improving Fe acquisition via increased rhizosphere acidification and auxin regulation. When overexpressed, transgenic plants show higher pyrophosphate hydrolysis and plasma membrane H+‐ATPase activity compared with the wild type, leading to increased rhizosphere acidification. The IbVP1‐overexpressing plants showed better growth, including enlarged root systems, under Fe‐sufficient or Fe‐deficient conditions. Increased ferric precipitation and ferric chelate reductase activity in the roots of transgenic lines indicate improved iron uptake, which is also confirmed by increased Fe content and up‐regulation of Fe uptake genes, e.g. FRO2,IRT1 and FIT. Carbohydrate metabolism is significantly affected in the transgenic lines, showing increased sugar and starch content associated with the increased expression of AGPase and SUT1 genes and the decrease in β‐amylase gene expression. Improved antioxidant capacities were also detected in the transgenic plants, which showed reduced H2O2 accumulation associated with up‐regulated ROS‐scavenging activity. Therefore, H+‐PPase plays a key role in the response to Fe deficiency by sweet potato and effectively improves the Fe acquisition by overexpressing IbVP1 in crops cultivated in micronutrient‐deficient soils.

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“…[5][6][7][8][9][10] However, H C -PPase also saliently localizes at the vascular tissues of plants, wherein this protein is predominantly localized at the plasma membrane (PM) of the sieve element companion cell (SE-CC) complexes. 8,[11][12][13] Thermodynamic, 14 genetic, immunohistochemical, and physiological evidence 8,15,16 is consistent with a reverse PPi synthase activity of H C -PPase at the PM in the phloem, where it plays an important role in PPi homeostasis and photosynthate partitioning. 10,[15][16][17] We contend that the magnitude of proton gradients associated with the tonoplast or PM location of this enzyme drives the protein's structurally congruent potential to work in a reversible manner -either in the synthesis or hydrolysis of its substrate, PPi.…”

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confidence: 60%

Structural basis for the reversibility of proton pyrophosphatase

Regmi

Pizzio

Gaxiola

2016

Plant Signaling & Behavior

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Proton Pyrophosphatase (H C -PPase) is an evolutionarily conserved enzyme regarded as a bona fide vacuolar marker. However, H C -PPase also localizes at the plasma membrane of the phloem, where, evidence suggests that it functions as a Pyrophosphate Synthase and participates in phloem loading and photosynthate partitioning. We believe that this pyrophosphate synthesising function of H C -PPase is fundamentally rooted to its molecular structure, and here we postulate, on the basis of published crystal structures of membrane-bound pyrophosphatases, a plausible mechanism of pyrophosphate synthesis.

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Plasma membrane localization of the type I H+-PPase AVP1 in sieve element–companion cell complexes from Arabidopsis thaliana

Cited by 54 publications

References 47 publications

Arabidopsis Type I Proton-Pumping Pyrophosphatase Expresses Strongly in Phloem, Where It Is Required for Pyrophosphate Metabolism and Photosynthate Partitioning

Arabidopsis Type I Proton-Pumping Pyrophosphatase Expresses Strongly in Phloem, Where It Is Required for Pyrophosphate Metabolism and Photosynthate Partitioning

H⁺‐pyrophosphatase IbVP1 promotes efficient iron use in sweet potato [Ipomoea batatas (L.) Lam.]

Structural basis for the reversibility of proton pyrophosphatase

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Plasma membrane localization of the type I H+-PPase AVP1 in sieve element–companion cell complexes from Arabidopsis thaliana

Cited by 54 publications

References 47 publications

Arabidopsis Type I Proton-Pumping Pyrophosphatase Expresses Strongly in Phloem, Where It Is Required for Pyrophosphate Metabolism and Photosynthate Partitioning

Arabidopsis Type I Proton-Pumping Pyrophosphatase Expresses Strongly in Phloem, Where It Is Required for Pyrophosphate Metabolism and Photosynthate Partitioning

H+‐pyrophosphatase IbVP1 promotes efficient iron use in sweet potato [Ipomoea batatas (L.) Lam.]

Structural basis for the reversibility of proton pyrophosphatase

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H⁺‐pyrophosphatase IbVP1 promotes efficient iron use in sweet potato [Ipomoea batatas (L.) Lam.]