Altered stomatal dynamics in ascorbate oxidase over-expressing tobacco plants suggest a role for dehydroascorbate signalling

• Published in: Journal of experimental botany Vol. 59; no. 4; pp. 729 - 737
• Main Authors: Fotopoulos, Vasileios, De Tullio, Mario C, Barnes, Jeremy, Kanellis, Angelos K
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.03.2008; Oxford Publishing Limited (England)
• Subjects: ABA; apoplast; ascorbate oxidase; Ascorbate Oxidase - genetics; Ascorbate Oxidase - metabolism; ascorbic acid; Biological and medical sciences; Cell physiology; cv. Xanthi; dehydroascorbic acid (DHA); Dehydroascorbic Acid - metabolism; Electric Conductivity; Enzymes; Fundamental and applied biological sciences. Psychology; Guard cells; Hydrogen; hydrogen peroxide; Hydrogen Peroxide - metabolism; Immunohistochemistry; Leaves; Molecular and cellular biology; Nicotiana - genetics; Nicotiana - metabolism; Nicotiana tabacum L; Oxidases; Peroxides; Plant epidermis; Plant Stomata - physiology; Plant Transpiration - genetics; Plant Transpiration - physiology; Plants; Plants, Genetically Modified; RESEARCH PAPER; Signal transduction; Signal Transduction - physiology; Stomata; Transgenic plants; Water - metabolism; water stress; ABA; dehydroascorbic acid (DHA); transgenic plants; ascorbic acid; stomata; apoplast; ascorbate oxidase; hydrogen peroxide; water stress; L., cv. Xanthi; Ascorbic acid; Stomata; Apoplast; Nicotiana tabacum; Water stress; cv. Xanthi; Dicotyledones; Sesquiterpenes; Angiospermae; Abscisic acid; Plant growth substance; Nicotiana tabacum L; Spermatophyta; Transgenic plant; Solanaceae
• ISSN: 0022-0957; 1460-2431
• DOI: 10.1093/jxb/erm359

Control of stomatal aperture is of paramount importance for plant adaptation to the surrounding environment. Here, we report on several parameters related to stomatal dynamics and performance in transgenic tobacco plants (Nicotiana tabacum L., cv. Xanthi) over-expressing cucumber ascorbate oxidase (AO), a cell wall-localized enzyme of uncertain biological function that oxidizes ascorbic acid (AA) to monodehydroascorbic acid which dismutates yielding AA and dehydroascorbic acid (DHA). In comparison to WT plants, leaves of AO over-expressing plants exhibited reduced stomatal conductance (due to partial stomatal closure), higher water content, and reduced rates of water loss on detachment. Transgenic plants also exhibited elevated levels of hydrogen peroxide and a decline in hydrogen peroxide-scavenging enzyme activity. Leaf ABA content was also higher in AO over-expressing plants. Treatment of epidermal strips with either 1 mM DHA or 100 μM hydrogen peroxide resulted in rapid stomatal closure in WT plants, but not in AO-over-expressing plants. This suggests that signal perception and/or transduction associated with stomatal closure is altered by AO over-expression. These data support a specific role for cell wall-localized AA in the perception of environmental cues, and suggest that DHA acts as a regulator of stomatal dynamics.