31P NMR studies on the effect of phosphite on Phytophthora palmivora

Niere, Julie O.; Griffith, Julia M.; Grant, Bruce

doi:10.1099/00221287-136-1-147

Cited by 32 publications

(14 citation statements)

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“…This view is corroborated by the observation that 0.1 to 3 mM Phi markedly inhibits the growth of Phytophthora mycelia in sterile culture (Smillie et al, 1989). 31P-NMR spectroscopy has revealed that Phi perturbs P metabolism in Phytophtkova by causing a massive accumulation of poly-P and PPi but not sugar-P or nucleotide-P pools Niere et al, 1990Niere et al, , 1994). Phi's toxicity in Pkytophtkora sp.…”

Section: ~ -supporting

confidence: 60%

“…Poly-P, which rarely occurs in higher plants (Harold, 1966;Jeffrey, 19681, was also undetectable in the Phi-treated B. nigra seedlings. In these respects, the effects of Phi on B. nigra are very different from those that it elicits in Phytophthora sp., in which approximately 1 mM Phi causes massive accumulation of PPi and poly-Ps and a significant increase in Pi Niere et al, 1990Niere et al, , 1994.…”

Section: Effect Of Phi On Protein Content and Activities Of Pepase Pmentioning

confidence: 99%

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The Fungicide Phosphonate Disrupts the Phosphate-Starvation Response in Brassica nigra Seedlings

et al. 1996

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The development of Brassica nigra seedlings over 20 d of growth was disrupted by the fungicide phosphonate (Phi) i n a manner inversely correlated with nutritional inorganic phosphate (Pi) levels.The growth of Pi-sufficient (1.25 mM Pi) seedlings was suppressed when 10, but not 5, mM Phi was added to the nutrient medium. I n contrast, the fresh weights and rookshoot ratios of Pi-limited (0.1 5 mM) seedlings were significantly reduced at 1.5 mM Phi, and they progressively declined to about 40% of control values as medium Phi concentration was increased to 10 mM. lntracellular Pi levels generally decreased in Phi-treated seedlings, and Phi accumulated in leaves and roots t o levels up t o 6-and 16-fold that of Pi i n Pi-sufficient and Pi-limited plants, respectively. Extractable activities of the Pi-starvation-inducible enzymes phosphoenolpyruvate phosphatase and inorganic pyrophosphate-dependent phosphofructokinase were unaltered in Pi-sufficient seedlings grown on 5 or 10 mM Phi. However, when Pi-limited seedlings were grown on 1.5 to 10 mM Phi (a) the induction of phosphoenolpyruvate phosphatase and inorganic pyrophosphate-dependent phosphofructokinase activities by Pi limitation was reduced by 40 to 90%, whereas (b) soluble protein concentrations and the activities of the ATP-dependent phosphofructokinase and pyruvate kinase were unaffected. It is concluded that Phi specifically interrupts processes involved i n regulation of the Pi-starvation response i n B. nigra. ~ -The Phi anion (HP03-) is an isostere of the Pi anion in which hydrogen replaces one of the oxygens bound to the P atom. In spite of the apparent similarity, most enzymes that catalyze the transfer of Pi groups can distinguish between the two anions. Phi was traditionally regarded as inert with respect to plant and animal metabolism and was once used as a buffer in systems in which Pi was unsuitable (Robertson and Boyer, 1956). Evidence suggesting that Phi is not biologically inert began to accumulate following the discovery that foliar applications or trunk injections of Fosetyl-A1 (aluminum tris-O-ethyl Phi) effectively suppress severa1 soil-borne plant diseases caused by pseudofungi belonging to the order Oomycetes, particularly Phytophthora sp. (Williams et al

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Section: ~ -supporting

confidence: 60%

Section: Effect Of Phi On Protein Content and Activities Of Pepase Pmentioning

confidence: 99%

The Fungicide Phosphonate Disrupts the Phosphate-Starvation Response in Brassica nigra Seedlings

et al. 1996

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“…Phi acts as a systemic fungicide against several species of fungi (Guest and Grant, 1991). Its toxicity appears to be due to a combination of factors, including decrease in total adenylate pool, accumulation of poly-and pyrophosphates, and inhibition of several enzymes involved in the glycolytic and pentose Pi pathways Niere et al, 1990Niere et al, , 1994Guest and Grant, 1991;Barchietto et al, 1992;Stehmann and Grant, 2000). Furthermore, addition of Phi to Pi-starved yeast resulted in reduced levels of sugar Pis, pyrophosphates, and polyphosphates, and it also inhibited Pi stress-repressible acid phosphatase (McDonald et al, 2001b).…”

Section: Discussionmentioning

confidence: 99%

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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“…A number of studies have identified alterations to fungal metabolism Niere et al, 1990Niere et al, , 1994Barchietto et al, 1992) and changes of morphology (Jiang, 1990;Jiang & Grossmann, 1992). These changes might account for both direct fungal inhibition and modification of the interactions between host and parasite.…”

Section: Introductionmentioning

confidence: 99%

Phosphonate transport in Phytophthora capsici

1997

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Phosphate was shown to reverse the in vitro activity of phosphonate ions against P. capsici (strain 375) more efficiently in liquid than in solid media. Phosphonate transport by mycelia incubated in aqueous solutions was enhanced by a previous phosphate starvation and the presence of K þ cations. The intracellular phosphonate concentration reached a constant level and this concentration, which is a function of the external concentration, fits a hyperbolic relationship. Phosphonate transport was greatly stimulated when mycelia were incubated in modified Ribeiro's medium. In the absence of any phosphorus source in the growth medium, the phosphate content of mycelia at stationary phase of growth decreased. This sign of phosphate deficiency was intensified in the presence of phosphonate. INTRODUCTIONPhosphonate is known to be the systemicallymobile degradation product of the anti-oomycete fungicide fosetyl-Al (Bompeix & Saindrenan, 1984;Fenn & Coffey, 1984;Darakis et al., 1985). This anion was shown to be the active metabolite of the fungicide, since in both soil and plant tissues, fosetyl-Al breaks down rapidly to phosphonate (Smilie et al., 1988;Fenn & Coffey, 1989). Contrary to other systemic fungicides, phosphonate was shown to possess only weak direct activity against some species of Phytophthora despite its ability to control these pathogens in vivo (Guest, 1984(Guest, , 1986. In fact, phosphonate reduces the mycelial growth of several species of Phytophthora when applied directly during in vitro tests, but at concentrations generally higher than those achieved in phosphonate-or fosetyl-Al-treated plants Nemestothy & Guest, 1990). However, in Phytophthora species that are more sensitive in vitro, the phosphonate content of plant tissues could account for direct inhibition of fungal growth (Bompeix & Saindrenan, 1984;Darakis et al., 1985;Guest & Grant, 1991).Recent studies on the mode of action of phosphonate are orientated towards the possibility that the fungus is the primary target of the compound, whereas the plant's natural defence mechanisms have the main role in the inhibition of fungal growth, particularly in cases where species are more sensitive in vivo Guest & Grant, 1991;Barchietto et al., 1992). A number of studies have identified alterations to fungal metabolism Niere et al., 1990Niere et al., , 1994Barchietto et al., 1992) and changes of morphology (Jiang, 1990;Jiang & Grossmann, 1992). These changes might account for both direct fungal inhibition and modification of the interactions between host and parasite. It was suggested, therefore, that a perturbation of phosphorus metabolism may also affect the virulence mechanisms of the pathogen (Saindrenan et al., 1990;Smillie et al., 1990;Guest, 1995). However, little is known about the relationships between the direct and the indirect action. Furthermore, it was established that there is a phosphonate/phosphate antagonism within the fungal cell, since phosphate (Pi) sometimes reversed the antifungal action of phosphonate in in vitro tests (Bompeix & ...

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31P NMR studies on the effect of phosphite on Phytophthora palmivora

Cited by 32 publications

References 43 publications

The Fungicide Phosphonate Disrupts the Phosphate-Starvation Response in Brassica nigra Seedlings

The Fungicide Phosphonate Disrupts the Phosphate-Starvation Response in Brassica nigra Seedlings

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

Phosphonate transport in Phytophthora capsici

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