Symplastic entry and phloem translocation of phosphonate

Ouimette, D.G.; Coffey, Michael D.

doi:10.1016/0048-3575(90)90143-p

Cited by 50 publications

(21 citation statements)

References 34 publications

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“…The mechanism was unclear, but by accumulation of Phi in the root vacuoles, this prevents the toxic buildup of Phi occurring in other parts of tissues, such as the shoots. As Phi is phloem mobile (Ouimette and Coffey 1990;Schroetter et al 2006), the small foliar application of Phi would be translocated to the roots, where it would accumulate and produce localized toxicity. This could explain why the komatsuna root under low P conditions (the hydroponic experiment) was more sensitive to Phi than the shoot, and even a small amount of Phi from foliar application was sufficient to severely damage the root without visibly damaging the shoot.…”

Section: Discussionmentioning

confidence: 97%

Growth response of komatsuna (Brassica rapa var. peruviridis) to root and foliar applications of phosphite

et al. 2008

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Soil and hydroponic culture experiments were conducted to investigate the effects of phosphite (Phi) as phosphorus (P) fertilizer via root and foliar applications on the growth and P supply of komatsuna. In both experiments, root P treatments were combinations of Phi and phosphate (Pi) at different Pi:Phi ratios, for a total of high P level (92 mg P pot −1 ; the soil experiment) or low P level (0.05 mM P; the hydroponic experiment). Foliar P treatments were deionized water (control), a Pi solution and a Phi solution at low concentration of 0.05% P 2 O 5 . In both experiments, shoot dry weight of plants significantly decreased as Pi:Phi ratio decreased. In the soil experiment, plants grew abnormally at a Pi:Phi ratio of 25:75 and died when P was applied to soil entirely as Phi form (0:100 treatment). In the hydroponic experiment, no visible damage was found in shoot but root growth was strongly inhibited with severe damage symptoms at low Pi:Phi ratios. Total P concentration in plant decreased significantly with decreasing Pi:Phi ratio, especially in the hydroponic experiment. Foliar application of Phi although greatly increased total P of plants compared to that of Pi in both experiments, it did not improve but further decreased plant growth at low Pi:Phi ratios in the soil experiment and at all Pi:Phi ratios in the hydroponic experiment. The results of this study clearly indicated that Phi could not be used as P fertilizer by komatsuna plants via both application methods and could not substitute P at any rate at either low or high level. No beneficial effect of Phi was detected even when it was applied at low rate or applied in combination with Pi at different ratios. The effects of Phi were strongly dependent on the P nutrition status of plants; and plants that were not sufficiently fertilized with Pi may become vulnerable to Phi even at low levels.

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Section: Discussionmentioning

confidence: 97%

Growth response of komatsuna (Brassica rapa var. peruviridis) to root and foliar applications of phosphite

et al. 2008

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“…Phi is rapidly absorbed and translocated within the plant (Guest and Grant, 1991). The uptake is pH dependent and subject to competition by Pi (Ouimette and Coffey, 1990). Furthermore, mobility of Phi in both xylem and phloem is similar to that of Pi (Ouimette and Coffey, 1989).…”

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confidence: 93%

Phosphite, an Analog of Phosphate, Suppresses the Coordinated Expression of Genes under Phosphate Starvation

et al. 2002

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Phosphate (Pi) and its analog phosphite (Phi) are acquired by plants via Pi transporters. Although the uptake and mobility of Phi and Pi are similar, there is no evidence suggesting that plants can utilize Phi as a sole source of phosphorus. Phi is also known to interfere with many of the Pi starvation responses in plants and yeast (Saccharomyces cerevisiae). In this study, effects of Phi on plant growth and coordinated expression of genes induced by Pi starvation were analyzed. Phi suppressed many of the Pi starvation responses that are commonly observed in plants. Enhanced root growth and root to shoot ratio, a hallmark of Pi stress response, was strongly inhibited by Phi. The negative effects of Phi were not obvious in plants supplemented with Pi. The expression of Pi starvation-induced genes such as LePT1, LePT2, AtPT1, and AtPT2 (high-affinity Pi transporters); LePS2 (a novel acid phosphatase); LePS3 and TPSI1 (novel genes); and PAP1 (purple acid phosphatase) was suppressed by Phi in plants and cell cultures. Expression of luciferase reporter gene driven by the Pi starvation-induced AtPT2 promoter was also suppressed by Phi. These analyses showed that suppression of Pi starvation-induced genes is an early response to addition of Phi. These data also provide evidence that Phi interferes with gene expression at the level of transcription. Synchronized suppression of multiple Pi starvation-induced genes by Phi points to its action on the early molecular events, probably signal transduction, in Pi starvation response.Phosphate (Pi) is one of the major plant nutrients that influences virtually all the biochemical processes and developmental phases of plants. In the absence of Pi, plants exhibit characteristic deficiency symptoms including anthocyanin accumulation, enhanced root growth, and increased root to shoot ratio. The ability of plants to acquire Pi also increases during this period. Molecular dissection of responses to Pi starvation has provided evidence for coordinated expression of genes, including Pi transporters (Raghothama, , 2000. Pi transporters are involved in acquiring Pi against the concentration gradient by an energy-mediated proton cotransport mechanism (Ullrich-Eberius et al., 1981). They are also known to transport ions such as arsenate, vanadate, and phosphite (Phi; Guest and Grant, 1991;Marschner, 1995).Phi (HPO 3 2Ϫ ), also referred to as phosphorous acid or phosphonate, is an isostere of the Pi anion in which one of the oxygens bound to the P atom is replaced by hydrogen. The term Phi is used here to describe the alkali metal salts of phosphorous acid as suggested by Carswell et al. (1996). Phi is used extensively as a fungicide and also sold as a superior source of Pi (Guest and Grant, 1991;Rickard, 2000; McDonald et al., 2001a). Phi is rapidly absorbed and translocated within the plant (Guest and Grant, 1991). The uptake is pH dependent and subject to competition by Pi (Ouimette and Coffey, 1990). Furthermore, mobility of Phi in both xylem and phloem is similar to that of Pi (Ouimette...

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“…Phosphite (H 2 PO 3 -) is an isostere of the phosphate anion (H 2 PO 4 -) in which one of the oxygen atoms bonded to the P atom is replaced by hydrogen (Ouimette and Coffey, 1990). Due to the structural similarity of these anions and the kinetic properties of plant phosphate transporters, phosphite is transported by high-affinity phosphate transporters (D'arcy-Lameta and Bompeix, 1991).…”

Section: Introductionmentioning

confidence: 99%

The effects of phosphite on strawberry yield and fruit quality

Estrada-Ortiz

Trejo-Téllez

Gómez-Merino

et al. 2013

J. Soil Sci. Plant Nutr.

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Phosphite (H 2 PO 3 -; Phi) has been shown to increase fruit quality and activate plant defense mechanisms in plants when provided in a nutrient state with sufficient phosphorous. In this study, five solutions containing different percentages of Phi (0, 20, 30, 40 and 50%) in Steiner's solution were evaluated during the flowering and fructification stages; the Steiner' s nutrient solution was kept al 50% during the flowering stage and at 75% from the beginning of the fructification stage on. The objective was to determine the effects of phosphite on total P concentration in leaves, yield, pH, electrical conductivity (EC), anthocyanin concentration, and fruit size of strawberries (cv. Festival). The experiments were performed in a tunnel-type greenhouse using drip irrigation and volcanic rock (volcanic gravel) as substrate. In the fruit development phase, the concentration of P in the leaves was proportional to the level of Phi used. Although no significant differences were observed when compared to the control, the addition of 20% Phi slightly improved yield and fruit size. The highest pH, EC and anthocyanin concentration were identified in the fruit of plants treated with 30% Phi. Our findings suggest that supplying Phi at 30% or less in the nutrient solution does not significantly affect yield but does affect fruit quality and activates plant defense mechanisms by producing a higher concentration of anthocyanins.

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Symplastic entry and phloem translocation of phosphonate

Cited by 50 publications

References 34 publications

Growth response of komatsuna (Brassica rapa var. peruviridis) to root and foliar applications of phosphite

Growth response of komatsuna (Brassica rapa var. peruviridis) to root and foliar applications of phosphite

Phosphite, an Analog of Phosphate, Suppresses the Coordinated Expression of Genes under Phosphate Starvation

The effects of phosphite on strawberry yield and fruit quality

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