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Factors that affect leaf extracellular ascorbic acid content and redox status
Author(s) -
Burkey Kent O.,
Eason Gwendolyn,
Fiscus Edwin L.
Publication year - 2003
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1034/j.1399-3054.2003.1170106.x
Subject(s) - apoplast , dehydroascorbic acid , ascorbic acid , ozone , extracellular , chemistry , phaseolus , botany , symplast , zoology , horticulture , food science , biochemistry , biology , cell wall , organic chemistry
Leaf ascorbic acid content and redox status were compared in ozone‐tolerant (Provider) and ozone‐sensitive (S156) genotypes of snap bean ( Phaseolus vulgaris L.). Plants were grown in pots for 24 days under charcoal‐filtered air (CF) conditions in open‐top field chambers and then maintained as CF controls (29 nmol mol −1 ozone) or exposed to elevated ozone (71 nmol mol −1 ozone). Following a 10‐day treatment, mature leaves of the same age were harvested early in the morning (06:00–08:00 h) or in the afternoon (13:00–15:00 h) for analysis of ascorbic acid (AA) and dehydroascorbic acid (DHA). Vacuum infiltration methods were used to separate leaf AA into apoplast and symplast fractions. The total ascorbate content [AA + DHA] of leaf tissue averaged 28% higher in Provider relative to S156, and Provider exhibited a greater capacity to maintain [AA + DHA] content under ozone stress. Apoplast [AA + DHA] content was 2‐fold higher in tolerant Provider (360 nmol g −1 FW maximum) relative to sensitive S156 (160 nmol g −1 FW maximum) regardless of sampling period or treatment, supporting the hypothesis that extracellular AA is a factor in ozone tolerance. Apoplast [AA + DHA] levels were significantly higher in the afternoon than early morning for both genotypes, evidence for short‐term regulation of extracellular ascorbate content. Total leaf ascorbate was primarily reduced with AA/[AA + DHA] ratios of 0.81–0.90. In contrast, apoplast AA/[AA + DHA] ratios were 0.01–0.60 and depended on genotype and ozone treatment. Provider exhibited a greater capacity to maintain extracellular AA/[AA + DHA] ratios under ozone stress, suggesting that ozone tolerance is associated with apoplast ascorbate redox status.