Distribution and Cellular Localization of Ascorbic Acid Oxidase in the Maize Root Tip

Mertz, Dan

doi:10.2307/2439333

Cited by 23 publications

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“…1), with a rather sharp decline in activity above pH 6.0. This pattern agrees with the pH optimum for AAO reported by others (Dawson and Magee, 1955;Mertz, 1961). All subsequent experiments were conducted with the cell wall fraction at pH 5.6.…”

supporting

confidence: 90%

“…AAO activity was correlated with the growth rate in bud tissue (r = 0.902); its activity declined by day 12, probably due to a general increase in protein content. The association of AAO with the walls of cells undergoing rapid growth has been reported in root tips of various plants (Honda, 1955;Jensen and Kavaljian, 1956;Mertz, 1961;Reid, 1941) and in fruits and leaves of zucchini squash (Cucurbita pepo L.) (Lin and Vamer, 1991). AAO activity also increased rapidly during the growth of cultured pumpkin (Cucurbita sp.)…”

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confidence: 99%

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Ascorbic Acid Oxidase Activity in Apple Buds: Relation to Thidiazuron-induced Lateral Budbreak

Wang¹,

Faust²

1992

HortSci

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The activity of ascorbic acid oxidase (AAO) was studied in apple (Malus domestica Borkh.) buds during dormancy and thidiazuron-induced budbreak. In dormant buds, activity of AAO was low compared with buds that were treated with thidiazuron and had resumed growth. An increase in AAO activity began at the time of metabolic transition from dormancy to budbreak. The highest level of activity was reached 10 days after thidiazuron induction during the expansion growth phase. In vitro AAO activity of apple bud extract was increased by addition of Cu (CuSO) and inhibited by Cu-chelating agents, diethyldithiocarbamate (DDC), sodium azide (NaN), and 8-hydroxyquinoiine (8-OH-Q). In vivo treatment of apple buds with Cu-chelating agents inhibited AAO activity and bud growth but not budbreak. Chemical name used: N- phenyl -N' -1,2,3-thidiazol-5-ylurea (thidiazuron).

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confidence: 90%

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Ascorbic Acid Oxidase Activity in Apple Buds: Relation to Thidiazuron-induced Lateral Budbreak

Wang¹,

Faust²

1992

HortSci

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“…High ascorbate oxidase activity often correlates with rapid cell expansion [e.g. in cowpea roots (Reid, ), maize roots and mesocotyls (Mertz, , ), pumpkin cell‐suspension cultures (Esaka et al ., ), courgette leaves and fruits (Lin and Varner, ), cultured tobacco cells (Kato & Esaka, ) and cotton trichomes (Li et al ., )], an observation that has been difficult to rationalise if viewed in terms of the enzyme's ability to destroy ascorbate, which is widely regarded as a ‘beneficial’ antioxidant associated with vitality and growth. Lin and Varner () proposed the alternative view – that the key effect of ascorbate oxidase should be viewed as beneficially generating DHA rather than as detrimentally destroying ascorbate.…”

Section: Discussionmentioning

confidence: 99%

Oxalyltransferase, a plant cell‐wall acyltransferase activity, transfers oxalate groups from ascorbate metabolites to carbohydrates

Dewhirst

Fry

2018

The Plant Journal

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SummaryIn the plant apoplast, ascorbate is oxidised, via dehydroascorbic acid, to O‐oxalyl esters [oxalyl‐l‐threonate (OxT) and cyclic oxalyl‐l‐threonate (cOxT)]. We tested whether OxT and cOxT can donate the oxalyl group in transacylation reactions to form oxalyl‐polysaccharides, potentially modifying the cell wall. [oxalyl‐14C]OxT was incubated with living spinach (Spinacia oleracea) and Arabidopsis cell‐suspension cultures in the presence or absence of proposed acceptor substrates (carbohydrates). In addition, [14C]OxT and [14C]cOxT were incubated in vitro with cell‐wall enzyme preparations plus proposed acceptor substrates. Radioactive products were monitored electrophoretically. Oxalyltransferase activity was detected. Living cells incorporated oxalate groups from OxT into cell‐wall polymers via ester bonds. When sugars were added, [14C]oxalyl‐sugars were formed, in competition with OxT hydrolysis. Preferred acceptor substrates were carbohydrates possessing primary alcohols e.g. glucose. A model transacylation product, [14C]oxalyl‐glucose, was relatively stable in vivo (half‐life >24 h), whereas [14C]OxT underwent rapid turnover (half‐life ~6 h). Ionically wall‐bound enzymes catalysed similar transacylation reactions in vitro with OxT or cOxT as oxalyl donor substrates and any of a range of sugars or hemicelluloses as acceptor substrates. Glucosamine was O‐oxalylated, not N‐oxalylated. We conclude that plants possess apoplastic acyltransferase (oxalyltransferase) activity that transfers oxalyl groups from ascorbate catabolites to carbohydrates, forming relatively long‐lived O‐oxalyl‐carbohydrates. The findings increase the range of known metabolites whose accumulation in vivo indicates vitamin C catabolism. Possible signalling roles of the resulting oxalyl‐sugars can now be investigated, as can the potential ability of polysaccharide oxalylation to modify the wall's physical properties.

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“…With increasing research on the function of AO, an opinion prevailed that AO controls cell expansion during plant development and growth, although the actual mechanism of its action remains unknown (Kato et al, 2000;Lin et al, 1991;Mertz, 1961). The expression analysis of CmAO1 exhibited that the transcript abundance declined in young green fruit, while the expression increased during the fruit development and growth, reaching the peak at the outer mesocarp, and declined in over-ripe fruit (Sanmartin et al, 2007).…”

Section: Discussionmentioning

confidence: 99%

Cloning and Expression Analysis of an Ascorbate Oxidase (AO) Gene from Strawberry (Fragaria×ananassa cv. Toyonaka)

Lin¹,

Gu²,

Tang³

et al. 2013

JAS

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In this study, a total 1737 bp ascorbate oxidase (AO) gene encoding a 578 amino acid protein was cloned from strawberry (Fragaria×ananassa cv. Toyonaka). Real-time quantitative expression analysis was conducted on FaAO gene of strawberry fruits during 7 developmental stages and in 5 strawberry tissues. The results revealed that during 7 fruit developmental stages, FaAO expressing level gradually increased in yonger stages, and declined dramatically in maturing stages, in which it could barely be detected. According to experimental results, we can conclude that FaAO expresses at a higher level in younger fruits, and lower in latter stages. This could be related to the fact that younger fruits are growing actively, and FaAO has a significant effect on facilitating fruit growth. Results for expression in 5 tissues indicated the highest expression was detected in flowers, and the lowest in fruit tissue (at full red stage). One of the possible reasons is that intense respiration and high ethylene synthesis occur in the mature fruits, repressing the expression of FaAO gene in strawberry fruits. Also, it could be a reason why the ascorbic acid (AA) content in mature fruits is higher than that in other tissues and stages. The differences of expression results among 7 developmental stages and 5 tissues indicated a novel expression pattern of FaAO. We propose that FaAO is correlated with strawberry growth and development, the depression of the FaAO expression can lead to apparent accumulation of AA in strawberry plant.

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Distribution and Cellular Localization of Ascorbic Acid Oxidase in the Maize Root Tip

Cited by 23 publications

References 0 publications

Ascorbic Acid Oxidase Activity in Apple Buds: Relation to Thidiazuron-induced Lateral Budbreak

Ascorbic Acid Oxidase Activity in Apple Buds: Relation to Thidiazuron-induced Lateral Budbreak

Oxalyltransferase, a plant cell‐wall acyltransferase activity, transfers oxalate groups from ascorbate metabolites to carbohydrates

Cloning and Expression Analysis of an Ascorbate Oxidase (AO) Gene from Strawberry (Fragaria×ananassa cv. Toyonaka)

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