Observation of Cytoplasmic and Vacuolar Malate in Maize Root Tips by <sup>13</sup>C-NMR Spectroscopy

Chang, Keejong; Roberts, Justin K. M.

doi:10.1104/pp.89.1.197

Cited by 45 publications

(15 citation statements)

References 12 publications

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“…The fresh weight of the root segment samples was about 3.0 g each. Details of the perchloric acid extraction and NMR methods are given elsewhere (Chang and Roberts, 1989;Roberts et al, 1992).…”

Section: Analyses Of Organic Osmolytesmentioning

confidence: 99%

Growth, Water Relations, and Accumulation of Organic and Inorganic Solutes in Roots of Maize Seedlings during Salt Stress

et al. 1997

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Seedlings of maize (Zea mays L. cv Pioneer 3906), hydroponically grown in the dark, were exposed to NaCl either gradually (salt acclimation) or in one step (salt shock). In the salt-acclimation treatment, root extension was indistinguishable from that of unsalinized controls for at least 6 d at concentrations up to 100 mM NaCI. By contrast, salt shock rapidly inhibited extension, followed by a gradual recovery, so that by 24 h extension rates were the same as for controls, even at 150 mM NaCI. Salt shock caused a rapid decrease in root water and solute potentials for the apical zones, and the estimated turgor potential showed only a small decline; similar but more gradual changes occurred with salt acclimation. The 5-bar decrease in root solute potential with salt shock (150 mM NaCI) during the initial 1 O min of exposure could not be accounted for by dehydration, indicating that substantial osmotic adjustment occurred rapidly. Changes in concentration of inorganic solutes (Na+, K+, and CI-) and organic solutes (proline, sucrose, fructose, and glucose) were measured during salt shock. The contribution of these solutes to changes in root solute potential with salinization was estimated.

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Section: Analyses Of Organic Osmolytesmentioning

confidence: 99%

Growth, Water Relations, and Accumulation of Organic and Inorganic Solutes in Roots of Maize Seedlings during Salt Stress

et al. 1997

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“…Extracts of tissues prepared with concentrations of perchloric acid ranging from 4 to 70% have been used in NMR studies to quantitate many metabolites, including amino acids (Chang and Roberts, 1989;Sumegi et al, 1992;Gout et al, 1993). Qualitatively, our extracts made with phosphate buffer and perchloric acid were similar.…”

Section: Quantitation Of the Synthesis Of Ser Via The Cdc/shmt And C1mentioning

confidence: 99%

13C Nuclear Magnetic Resonance Detection of Interactions of Serine Hydroxymethyltransferase with C1-Tetrahydrofolate Synthase and Glycine Decarboxylase Complex Activities in Arabidopsis

et al. 1996

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~~ ~~ I n C, plants, serine synthesis is associated with photorespiratory glycine metabolism involving the tetrahydrofolate (THF)-dependent activities of the glycine decarboxylase complex (CDC) and serine hydroxymethyl transferase (SHMT). Alternatively, THF-dependent serine synthesis can occur via the C1 -THF synthase/SHMT pathway. We used 13C nuclear magnetic resonance to examine serine biosynthesis by these two pathways i n Arabidopsis fhaliana (L.) Heynh.Columbia wild type. We confirmed the tight coupling of the CDC/ SHMT system and observed directly i n a higher plant the flux of formate through the C1 -THF synthase/SHMT system. l h e accumulation of 13C-enriched serine over 24 h from the CDC/SHMT activities was 4-fold greater than that from C1 -THF synthase/SHMT activities. Our experiments strongly suggest that the two pathways operate independently in Arabidopsis. Plants exposed to methotrexate and sulfanilamide, powerful inhibitors of THF biosynthesis, reduced serine synthesis by both pathways. l h e results suggest that continuous supply of THF is essential to maintain high rates of serine metabolism. Nuclear magnetic resonance is a powerful tool for the examination of THF-mediated metabolism in its natural cellular environment.Folate coenzymes mediate single-carbon transfers in a variety of cellular processes such as purine biosynthesis, amino acid metabolism, thymidylate synthesis, and chloroplast and mitochondrial protein synthesis. In spite of the pivotal role THF plays in cellular metabolism, studies of THF biosynthesis and THF-dependent metabolism in plants remain sparse. We have recently begun wideranging studies of folate metabolism in Datuva cells and Arabidopsis plants (Wu et al., 1993(Wu et al., , 1994 Prabhu et al., 1994). In this study we addressed the THF-dependent biosynthesis of Ser in intact plants of Arabidopsis tkaliana (L.) Heynh. Columbia wild type using I3C NMR.THF-dependent Gly and Ser metabolism are closely linked in a variety of organisms (Schirch, 1984). The use of a common pool of THF allows transfer of the a-C of Gly

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“…Most carbohydrates, amino acids and organic acids are extremely labile in the rhizosphere due to consumption by the indigenous microflora and resorption by roots (Jones & Darrah, 1994b;Jones, 1998;Owen & Jones, 2001). The release and availability of these compounds to microbes in the rhizosphere vary spatially along the root (McDougall & Rovira, 1970;Chang & Roberts, 1989;Jones & Darrah, 1995;Jaeger et al, 1999;Bringhurst et al, 2001), with plant age, and with environmental conditions (Curl & Truelove, 1986;Grayston et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

Role of sdhA and pfkA and catabolism of reduced carbon during colonization of cucumber roots by Enterobacter cloacae

Lohrke

et al. 2007

Microbiology

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We have been using a mutational approach to determine how plant-beneficial bacteria such as Enterobacter cloacae 501R3 obtain carbon and energy for colonization of subterranean portions of cucumber and other plants. Reduced carbon detected in cucumber root exudate consisted of 73.3 % amino acids, 22.2 % organic acids and 4.4 % carbohydrate. Ent. cloacae M2, a mini-Tn5 Km transposon mutant of strain 501R3, was severely reduced in in vitro growth relative to strain 501R3 on the mixture of amino acids and organic acids detected in cucumber root exudate when these compounds were supplied as the sole source of carbon and energy, but was similar in growth on the mixture of carbohydrates detected in this exudate. Molecular and biochemical characterization of Ent. cloacae M2 indicated that the transposon was inserted in sdhA, which encodes a subunit of succinate dehydrogenase. Ent. cloacae A-11, a mutant of strain 501R3 with a mini-Tn5 Km insertion in pfkA, was severely reduced in in vitro growth relative to strain 501R3 on the mixture of carbohydrates detected in cucumber root exudate, but similar in growth on the mixture of amino acids and organic acids. When strains A-11 and M2 were coapplied with strain 501R3 to cucumber seeds above carrying capacity in competitive root colonization assays, populations of strains A-11 and M2 were roughly one order of magnitude lower than those of strain 501R3 in cucumber rhizosphere, while populations of strains A-11 and M2 were similar to one other when coapplied to cucumber seeds. When Ent. cloacae strains were coapplied to cucumber seeds below carrying capacity, populations of A-11 and M2 were roughly two to three orders of magnitude lower than those of 501R3 in cucumber rhizosphere, and populations of A-11 were significantly lower than those of M2 when these two strains were coapplied to cucumber seed. The experiments reported here indicate an important role for pfkA and sdhA and the catabolism of carbohydrates, and of amino acids and organic acids, respectively, in the colonization of cucumber roots by Ent. cloacae. The results reported here also indicate that catabolism of carbohydrates by this bacterium is more important than catabolism of amino acids and organic acids at lower population densities, despite the much higher relative quantities of amino acids and organic acids detected in cucumber root exudate.

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Observation of Cytoplasmic and Vacuolar Malate in Maize Root Tips by ¹³C-NMR Spectroscopy

Cited by 45 publications

References 12 publications

Growth, Water Relations, and Accumulation of Organic and Inorganic Solutes in Roots of Maize Seedlings during Salt Stress

Growth, Water Relations, and Accumulation of Organic and Inorganic Solutes in Roots of Maize Seedlings during Salt Stress

13C Nuclear Magnetic Resonance Detection of Interactions of Serine Hydroxymethyltransferase with C1-Tetrahydrofolate Synthase and Glycine Decarboxylase Complex Activities in Arabidopsis

Role of sdhA and pfkA and catabolism of reduced carbon during colonization of cucumber roots by Enterobacter cloacae

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Observation of Cytoplasmic and Vacuolar Malate in Maize Root Tips by 13C-NMR Spectroscopy

Cited by 45 publications

References 12 publications

Growth, Water Relations, and Accumulation of Organic and Inorganic Solutes in Roots of Maize Seedlings during Salt Stress

Growth, Water Relations, and Accumulation of Organic and Inorganic Solutes in Roots of Maize Seedlings during Salt Stress

13C Nuclear Magnetic Resonance Detection of Interactions of Serine Hydroxymethyltransferase with C1-Tetrahydrofolate Synthase and Glycine Decarboxylase Complex Activities in Arabidopsis

Role of sdhA and pfkA and catabolism of reduced carbon during colonization of cucumber roots by Enterobacter cloacae

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Observation of Cytoplasmic and Vacuolar Malate in Maize Root Tips by ¹³C-NMR Spectroscopy