Light‐dependent regulation of ascorbate in tomato by a monodehydroascorbate reductase localized in peroxisomes and the cytosol. Issue 3 (6th November 2012)

• Record Type: Journal Article
• Authors: Gest, Noé; Garchery, Cécile; Gautier, Hélène; Jiménez, Ana; Stevens, Rebecca
• Is Part Of: Plant biotechnology journal. Volume 11:Issue 3(2013:Apr.)
• Page Start: 344
• Page End: 354
• Publication Date: 2012-11-06
• Subjects: Plant biotechnology -- Periodicals; Plant genetic engineering -- Periodicals; 630.272
• DOI: 10.1111/pbi.12020
• Languages: English
• ISSNs: 1467-7644

Abstract

<abstract abstract-type="main" id="pbi12020-abs-0001"> <title>Summary</title> <p>Ascorbate is a powerful antioxidant in plants, and its levels are an important quality criteria in commercial species. Factors influencing these levels include environmental variations, particularly light, and the genetic control of its biosynthesis, recycling and degradation. One of the genes involved in the recycling pathway encodes a monodehydroascorbate reductase (MDHAR), an enzyme catalysing reduction of the oxidized radical of ascorbate, monodehydroascorbate, to ascorbate. In plants, MDHAR belongs to a multigene family. Here, we report the presence of an MDHAR isoform in both the cytosol and peroxisomes and show that this enzyme negatively regulates ascorbate levels in <italic>Solanum lycopersicum</italic> (tomato). Transgenic lines overexpressing MDHAR show a decrease in ascorbate levels in leaves, whereas lines where MDHAR is silenced show an increase in these levels in both fruits and leaves. Furthermore, the intensity of these differences is light dependent. The unexpected effect of this MDHAR on ascorbate levels cannot be explained by changes in the expression of Smirnoff–Wheeler pathway genes, or the activity of enzymes involved in degradation (ascorbate peroxidase) or recycling of ascorbate (dehydroascorbate reductase and glutathione reductase), suggesting a previously unidentified mechanism regulating ascorbate levels.</p> </abstract>