Counteractive Effects of ABA and GA3 on Extracellular and Intracellular pH and Malate in Barley Aleurone

Heimovaara-Dijkstra, S.; Heistek, Jolanda C.; Wang, Mei

doi:10.1104/pp.106.1.359

Cited by 42 publications

(30 citation statements)

References 8 publications

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“…Deembryonated seeds were imbibed in 0.1 M Tris-HCl buffer, pH 7.4, and 10 mM CaCl 2 (Hamabata et al, 1988;Heimovaara-Dijkstra et al, 1994) in the absence or presence of ABA and/or CHX (see Fig. 8 legend), MG132, and/or proteases inhibitors (see Fig.…”

Section: Plant Materials and Antibodiesmentioning

confidence: 99%

Regulation of Phosphoenolpyruvate Carboxylase Phosphorylation by Metabolites and Abscisic Acid during the Development and Germination of Barley Seeds

et al. 2008

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During barley (Hordeum vulgare) seed development, phosphoenolpyruvate carboxylase (PEPC) activity increased and PEPCspecific antibodies revealed housekeeping (103-kD) and inducible (108-kD) subunits. Bacterial-type PEPC fragments were immunologically detected in denatured protein extracts from dry and imbibed conditions; however, on nondenaturing gels, the activity of the recently reported octameric PEPC (in castor [Ricinus communis] oil seeds) was not detected. The phosphorylation state of the PEPC, as judged by L-malate 50% inhibition of initial activity values, phosphoprotein chromatography, and immunodetection of the phosphorylated N terminus, was found to be high between 8 and 18 d postanthesis (DPA) and during imbibition. In contrast, the enzyme appeared to be in a low phosphorylation state from 20 DPA up to dry seed. The time course of 32/36-kD, Ca 2+ -independent PEPC kinase activity exhibited a substantial increase after 30 DPA that did not coincide with the PEPC phosphorylation profile. This kinase was found to be inhibited by L-malate and not by putative protein inhibitors, and the PEPC phosphorylation status correlated with high glucose-6-phosphate to malate ratios, thereby suggesting an in vivo metabolic control of the kinase. PEPC phosphorylation was also regulated by photosynthate supply at 11 DPA. In addition, when fed exogenously to imbibing seeds, abscisic acid significantly increased PEPC kinase activity. This was further enhanced by the cytosolic protein synthesis inhibitor cycloheximide but blocked by protease inhibitors, thereby suggesting that the phytohormone acts on the stability of the kinase. We propose that a similar abscisic acid-dependent effect may contribute to produce the increase in PEPC kinase activity during desiccation stages.

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Section: Plant Materials and Antibodiesmentioning

confidence: 99%

Regulation of Phosphoenolpyruvate Carboxylase Phosphorylation by Metabolites and Abscisic Acid during the Development and Germination of Barley Seeds

et al. 2008

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“…Eight deembryonated half seeds were allowed to imbibe in 200 pL of buffer containing 100 mM Tris-HCI, pH 7.5,lO mM CaC1, (Hamabata et al, 1988;Heimovaara-Dijkstra et al, 1994), and 200 pCi of 32Pi. After 48 h of imbibition at room temperature, about half of the solution was absorbed by the seeds.…”

Section: In Situ 32p Labeling and Lmmunoprecipitationmentioning

confidence: 99%

In Vivo and in Vitro Phosphorylation of the Phosphoenolpyruvate Carboxylase from Wheat Seeds during Germination

et al. 1996

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Phosphoenolpyruvate carboxylase (PEPC) activity was detected in the aleurone endosperm of wheat (Triticum aestivum cv Chinese Spring) seeds, and specific anti-Sorghum C, PEPC polyclonal antibodies cross-reacted with 103-and 100-kD polypeptides present in dry seeds and seeds that had imbibed; in addition, a new, 108-kD polypeptide was detected 6 h after imbibition. l h e use of specific anti-phosphorylation-site immunoglobulin C (APS-lgC) identified the presence of a phosphorylation motif equivalent to that found in other plant PEPCs studied so far. The binding of this APS-lgC to the target protein promoted changes in the properties of seed PEPC similar to those produced by phosphorylation, as previously shown for the recombinant Sorghum leaf C, PEPC. In desalted seed extracts, an endogenous PEPC kinase activity catalyzed a bona fide phosphorylation of the target protein, as deduced from the immunoinhibition of the in vitro phosphorylation reaction by the APSIgC. In addition, the major, 103-kD PEPC polypeptide was also shown to be radiolabeled in situ 48 h after imbibition in [32Plorthophosphate. The ratio between optimal (pH 8) and suboptimal (pH 7.3 or 7.1) PEPC activity decreased during germination, thereby suggesting a change in catalytic rate related to an in vivo phosphorylation process. These collective data document that the components needed for the regulatory phosphorylation of PEPC are present and functional during germination of wheat seeds.

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“…Isolated aleurone layers of developing (Macnicol and Jacobsen, 1992) and mature barley (Mikola and Virtanen, 1980;Drozdowicz and Jones, 1993;Heimovaara-Dijkstra et al, 1994) and wheat grains (Hamabata et al, 1988) are capable of acidifying the medium in which they are incubated. The aleurone layer also plays an important role in acidifying the starchy endosperm in intact grain.…”

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confidence: 99%

Hormonal Regulation of Organic and Phosphoric Acid Release by Barley Aleurone Layers and Scutella

Drozdowicz

Jones

1995

Plant Physiol.

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The release of acid from the aleurone layer and scutellum of barley (Hordeum vulgare L. cv Himalaya) was investigated. Aleurone layers isolated from mature barley grains acidify the external medium by releasing organic and phosphoric acids. Cibberellic acid and abscisic acid stimulate acid release 2-fold over control tissue incubated in 10 mM CaCI,. Cibberellic acid causes medium acidification by stimulating the release of phosphoric and citric acids, whereas abscisic acid stimulates the release of malic acid. The accumulation of these acids in the incubation medium buffers the medium against changes in pH, particularly between pH 4 and 5. The amounts of amino acids that accumulate in the medium are low (2-1 2 nmol/layer) compared to other organic and phosphoric acids (100-500 nmol/layer). The scutellum does not play a major role in medium acidification but participates in the uptake of organic acids. The organic acid composition of the starchy endosperm changes after 3 d of imbibition; malic, succinic, and lactic acids decrease, whereas citric and phosphoric acids remain unchanged or increase. These results indicate that during postgerminative growth, the acidity of the starchy endosperm is maintained by acid production by the aleurone layer.

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Counteractive Effects of ABA and GA3 on Extracellular and Intracellular pH and Malate in Barley Aleurone

Cited by 42 publications

References 8 publications

Regulation of Phosphoenolpyruvate Carboxylase Phosphorylation by Metabolites and Abscisic Acid during the Development and Germination of Barley Seeds

Regulation of Phosphoenolpyruvate Carboxylase Phosphorylation by Metabolites and Abscisic Acid during the Development and Germination of Barley Seeds

In Vivo and in Vitro Phosphorylation of the Phosphoenolpyruvate Carboxylase from Wheat Seeds during Germination

Hormonal Regulation of Organic and Phosphoric Acid Release by Barley Aleurone Layers and Scutella

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