Solubilization of a Proline Dehydrogenase from Maize (<i>Zea mays</i> L.) Mitochondria

Rayapati, P. J.; Stewart, Cecil R.

doi:10.1104/pp.95.3.787

Cited by 90 publications

(59 citation statements)

References 11 publications

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“…Proline is metabolized to glutamate and TCA cycle acids in mitochondria and the ®rst enzyme on this pathway is PDH. Mitochondrial PDH activity decreases in maize seedlings exposed to low water potential (Rayapati and Stewart, 1991). This is consistent with the labelling data reported here.…”

Section: Proline Accumulation Is Not Limited By Precursor Supplysupporting

confidence: 92%

“…Proline oxidation to glutamate in mitochondria is catalysed by P5C dehydrogenase and proline dehydrogenase (PDH). Both PDH activity (Sells and Koeppe, 1981;Rayapati and Stewart, 1991) and its transcript levels are rapidly and strongly decreased in response to water stress (Kiyosue et al, 1996;Peng et al, 1996;Verbruggen et al, 1996;Nakashima et al, 1998). These observations show that the changes in biosynthesis and oxidation rate which lead to proline accumulation are at least partly controlled by changes in gene expression and enzyme amount.…”

Section: Introductionmentioning

confidence: 76%

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Proline Metabolism and Transport in Maize Seedlings at Low Water Potential

Raymond

Smirnoff²

2002

Annals of Botany

102

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The growing zone of maize seedling primary roots accumulates proline at low water potential. Endosperm removal and excision of root tips rapidly decreased the proline pool and greatly reduced proline accumulation in root tips at low water potential. Proline accumulation was not restored by exogenous amino acids. Labelling root tips with [ 14 C]glutamate and [ 14 C]proline showed that the rate of proline utilization (oxidation and protein synthesis) exceeded the rate of biosynthesis by ®ve-fold at high and low water potentials. This explains the reduction in the proline pool following root and endosperm excision and the inability to accumulate proline at low water potential. The endosperm is therefore the source of the proline that accumulates in the root tips of intact seedlings. Proline constituted 10 % of the amino acids released from the endosperm. [ 14 C]Proline was transported from the scutellum to other parts of the seedling and reached the highest concentration in the root tip. Less [ 14 C]proline was transported at low water potential but because of the lower rate of protein synthesis and oxidation, more accumulated as proline in the root tip. Despite the low biosynthesis capacity of the roots, the extent of proline accumulation in relation to water potential is precisely controlled by transport and utilization rate.ã 2002 Annals of Botany Company

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Section: Proline Accumulation Is Not Limited By Precursor Supplysupporting

confidence: 92%

Section: Introductionmentioning

confidence: 76%

Proline Metabolism and Transport in Maize Seedlings at Low Water Potential

Raymond

Smirnoff²

2002

Annals of Botany

102

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“…The other major factor that controls proline levels in higher plants is its degradation. Proline is oxidized to P5C in plant mitochondria by ProDH (Rayapati and Stewart, 1991). Figure 5 shows the evolution of ProDH activity in control and treated plants.…”

Section: Enzymes Of Proline Metabolismmentioning

confidence: 99%

The effect of NaCl on proline metabolism in Saussurea amara seedlings

Wang¹,

Liu²,

Kuan-hu³

et al. 2011

Afr. J. Biotechnol.

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Many plants accumulates proline dramatically under a variety of stress conditions, and this play an important role in regulation of osmotic homeostasis, prevention of damages caused by osmotic stresses, scavenging of reactive oxygen species and protection of cell structures. The regulation of proline accumulation in Saussurea amara seedlings and the activities of key enzymes involved in proline metabolism in response to salinity were studied, and 50-days-old seedlings were treated with NaCl (0, 100, 200, 300 and 400 mM) in this experiment. The results showed that proline contents were higher in leaves than in roots and increased significantly with NaCl concentration and treatment duration (P < 0.05). The activity of pyrroline-5-carboxylate synthetase (P5CS) increased at first and than decreased with increaso of NaCl concentration. The activities of orn-δ-aminotransferase (δ-OAT) and proline dehydrogenase (ProDH) increased and decreased, respectively, in response to elevated NaCl concentration and treatment duration. The data demonstrated that glutamate and ornthine pathway were activated by NaCl, and proline biosynthesis mainly depended on glutamate pathway under low-concentration NaCl condition, in which P5CS took dominant position. Conversely, the ornthine pathway was predominant.

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“…Seeds for the well-watered treatments were planted in vermiculite and watered with ABA solution until saturation (approximately 500 mL/100 g). Seeds for the drought stress treatment were germinated in moist paper towels for 24 h to ensure adequate water imbibition and then transplanted to vermiculite containing 100 mL water/100 g (10). The four ABA treatments used in this experiment were 0 (control), 11, 33, and 100 fM ABA.…”

Section: Methodsmentioning

confidence: 99%

Effect of Exogenous Abscisic Acid on Proline Dehydrogenase Activity in Maize (Zea mays L.)

Dallmier¹,

Stewart²

1992

Plant Physiol.

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Plant responses to drought stress include proline and abscisic acid (ABA) accumulation. Proline dehydrogenase (PDH) (EC 1.4.3) is the first enzyme in the proline oxidation pathway, and its activity has been shown to decline in response to water stress (PJ Rayapati, CR Stewart [1991] Plant Physiol 95: 787-791). In this investigation, we determined whether ABA treatment affects PDH activity in a manner similar to drought stress in maize (Zea mays L.) seedlings. Four exogenous ABA treatments (0, 11, 33, and 100 micromolar ABA) were applied to well-watered maize seedlings. Mitochondria were isolated and PDH was solubilized using Nonidet P-40. PDH activity was measured by the reduction of lodonitrotetrazolium violet under proline-dependent conditions. There was no effect of ABA on PDH activity at 33 and 100 micromolar ABA, but there was a 38% decline at 11 micromolar. This decline was less than the 69% reduction in activity under drought stress. Endogenous ABA determinations and plant growth rate showed that ABA entered the plant and was affecting metabolic processes. ABA treatments had a small effect on shoot and root proline concentration, whereas drought stress caused a 220% increase in root tissues. We conclude that ABA is not part of the pathway linking drought stress and decreased PDH activity.Plant responses to drought stress include ABA and proline accumulation (1,15). ABA has been shown to induce stomatal closure (9), as well as the transcription and translation of many ABA-responsive genes (1 1). Many of these genes are responsive to both water stress and endogenous ABA level (11 and references therein). The concurrent accumulation of proline and endogenous ABA in response to drought stress has resulted in speculation that ABA may trigger proline increases (12). However, Stewart and Voetberg (14) reported that ABA and proline accumulation were not necessarily linked in leaves of a wilty tomato (Lycopersiconflacca Mill.) This suggests that proline accumulation in response to drought stress may be independent of endogenous ABA levels in some species (14).For proline to accumulate, either synthesis from glutamic acid must be enhanced or the rate of oxidation must decrease, or both. PDH2 is the first enzyme in the proline oxidation Supported by U.S. Department of Agriculture 2 Abbreviations: PDH, proline dehydrogenase (EC 1.4.3); ddH20, distilled water. pathway (4). Recently, Rayapati and Stewart (10) reported the solubilization of PDH from maize (Zea mays L.) mitochondria. It was shown that extractable PDH activity was 10-fold lower in drought-stressed plants compared with wellwatered controls. The objective of the current investigation was to determine whether ABA caused a decline in extractable PDH in a manner similar to drought stress. We report that ABA does not affect extractable PDH activity in well-watered maize seedlings. MATERIALS AND METHODSMaize seedlings (Zea mays L. cv B73) were grown in the dark in vegetable crispers containing vermiculite at 30°C. The effects on PDH activity of fo...

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Solubilization of a Proline Dehydrogenase from Maize (Zea mays L.) Mitochondria

Cited by 90 publications

References 11 publications

Proline Metabolism and Transport in Maize Seedlings at Low Water Potential

Proline Metabolism and Transport in Maize Seedlings at Low Water Potential

The effect of NaCl on proline metabolism in Saussurea amara seedlings

Effect of Exogenous Abscisic Acid on Proline Dehydrogenase Activity in Maize (Zea mays L.)

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