TY - JOUR

T1 - Ascorbate in the Apoplast: Metabolism and Functions

AU - Sharova, E. I.

AU - Medvedev, S. S.

AU - Demidchik, V. V.

PY - 2020/3/1

Y1 - 2020/3/1

N2 - Abstract: Ascorbic acid (AA) is one of the most important antioxidants and redox-active substances of plants found in the apoplast. In the form of ascorbate anion, it can be exported to the cell wall through anion channels, where it is further oxidized to dehydroascorbic acid (DHA) and in this form is translocated back into the cytoplasm through as yet unidentified transporters. In the apoplast AA is exposed to both enzymatic and non-enzymatic oxidation, participating in the antioxidant and pro-oxidant processes: detoxification of O3, generation of hydroxyl radicals, reduction of phenoxyl radicals, etc. The intermediate product of the AA oxidation in apoplast, monodehydroascorbic acid (MDHA), serves as an extracellular electron acceptor for a number of redox chains localized at the plasma membrane (PM). All three forms of ascorbate, AA, DHA and MDHA, can potentially be involved in the cell signalling. Released from the cell through anionic channels during PM depolarization, AA can stimulate the production of hydroxyl radicals that activate Ca2+-permeable channels, and thus trigger Ca2+-signalling. Due to the ability to generate hydroxyl radicals and reduce phenoxyl radicals, AA affects cell wall extensibility and extension growth. By reducing Fe3+ to a freely soluble transport form of Fe2+, AA is involved in iron uptake by root cells. Apoplastic AA also plays an important role in a number of other processes and is potentially a unique signal-regulatory molecule functioning in the plant cell walls.

AB - Abstract: Ascorbic acid (AA) is one of the most important antioxidants and redox-active substances of plants found in the apoplast. In the form of ascorbate anion, it can be exported to the cell wall through anion channels, where it is further oxidized to dehydroascorbic acid (DHA) and in this form is translocated back into the cytoplasm through as yet unidentified transporters. In the apoplast AA is exposed to both enzymatic and non-enzymatic oxidation, participating in the antioxidant and pro-oxidant processes: detoxification of O3, generation of hydroxyl radicals, reduction of phenoxyl radicals, etc. The intermediate product of the AA oxidation in apoplast, monodehydroascorbic acid (MDHA), serves as an extracellular electron acceptor for a number of redox chains localized at the plasma membrane (PM). All three forms of ascorbate, AA, DHA and MDHA, can potentially be involved in the cell signalling. Released from the cell through anionic channels during PM depolarization, AA can stimulate the production of hydroxyl radicals that activate Ca2+-permeable channels, and thus trigger Ca2+-signalling. Due to the ability to generate hydroxyl radicals and reduce phenoxyl radicals, AA affects cell wall extensibility and extension growth. By reducing Fe3+ to a freely soluble transport form of Fe2+, AA is involved in iron uptake by root cells. Apoplastic AA also plays an important role in a number of other processes and is potentially a unique signal-regulatory molecule functioning in the plant cell walls.

KW - apoplast

KW - ascorbate

KW - cell wall

KW - growth regulation

KW - iron absorption

KW - membrane transport

KW - peroxidases

KW - plasma membrane

KW - redox reactions

KW - ROS

KW - ELONGATION ZONE

KW - REDOX STATE

KW - DEHYDROASCORBIC ACID

KW - III PEROXIDASES

KW - CELL-DIVISION

KW - GENE-EXPRESSION

KW - ROOT ELONGATION

KW - TOBACCO PLANTS

KW - HYDROGEN-PEROXIDE

KW - DEPENDENT CHANGES

UR - http://www.scopus.com/inward/record.url?scp=85082557460&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/fc80a2f3-a721-3537-8bb8-c15307bb4533/

U2 - 10.1134/S1021443720020156

DO - 10.1134/S1021443720020156

M3 - Review article

AN - SCOPUS:85082557460

VL - 67

SP - 207

EP - 220

JO - Russian Journal of Plant Physiology

JF - Russian Journal of Plant Physiology

SN - 1021-4437

IS - 2

ER -