Analysis of cytosolic isocitrate dehydrogenase and glutathione reductase 1 in photoperiod‐influenced responses to ozone using Arabidopsis knockout mutants

Abstract

Oxidative stress caused by ozone (O3) affects plant development, but the roles of specific redox-homeostatic enzymes in O3 responses are still unclear. While growth day length may affect oxidative stress outcomes, the potential influence of day length context on equal-time exposures to O3 is not known. In Arabidopsis Col-0, day length affected the outcome of O3 exposure. In short-days (SD), few lesions were elicited by treatments that caused extensive lesions in long days (LD). Lesion formation was not associated with significant perturbation of glutathione, ascorbate, NADP(H) or NAD(H). To investigate roles of two genes potentially underpinning this redox stability, O3 responses of mutants for cytosolic NADP-isocitrate dehydrogenase (icdh) and glutathione reductase 1 (gr1) were analysed. Loss of ICDH function did not affect O3-induced lesions, but slightly increased glutathione oxidation, induction of other cytosolic NADPH-producing enzymes and pathogenesis-related gene 1 (PR1). In gr1, O3-triggered lesions, salicylic acid accumulation, and induction of PR1 were all decreased relative to Col-0 despite enhanced accumulation of glutathione. Thus, even at identical irradiance and equal-time exposures, day length strongly influences phenotypes triggered by oxidants of atmospheric origin, while in addition to its antioxidant function, the GR-glutathione system seems to play novel signalling roles during O3 exposure.

NADPH-generating dehydrogenases: their role in the mechanism of protection against nitro-oxidative stress induced by adverse environmental conditions

“…By using the Arabidopsis cytosolic NADP-ICDH knockout mutant, it has been reported that the loss of this isozyme function does not markedly affect the response of Arabidopsis to ozone. However, other cytosolic NADPH-producing enzymes (G6PDH and NADP-ME) showed a significant increase which contributed to maintaining the status of NADPH redox (Dghim et al, 2013a). A similar increase in G6PDH and NADP-ME has also been reported in hybrid poplar leaves in response to ozone (Dghim et al, 2013b).…”

Regulating the Redox Gatekeeper: Vacuolar Sequestration Puts Glutathione Disulfide in Its Place

“…Loss of GR1 function also affects phytohormone signaling induced by ozone (Dghim et al, 2013). Sequestration of GSSG may be required to clear the cytosol of active signal under basal conditions, to avoid excessive oxidative stimulation under stress conditions, and to allow the termination of signaling.…”

Intracellular Redox Compartmentation and ROS-Related Communication in Regulation and Signaling

“…Growth in long days allows peroxisomal H 2 O 2 to trigger PR responses that are not apparent in plants grown in short days, an effect that is linked to protein phosphorylation status (Li et al, 2014). Longday contexts also favor the development of lesions in response to equal-time exposure of Arabidopsis to ozone, a condition that triggers an initial ROS burst and oxidative stress in the apoplast (Dghim et al, 2013).…”