Ozone-Sensitive Arabidopsis Mutants with Deficiencies in Photorespiratory Enzymes

Abstract

An ozone-sensitive mutant was isolated from T-DNA-tagged lines of Arabidopsis thaliana. The T-DNA was inserted at a locus on chromosome 3, where two genes encoding glycolate oxidases, GOX1 and GOX2, peroxisomal enzymes involved in photorespiration, reside contiguously. The amounts of the mutant's foliar transcripts for these genes were reduced, and glycolate oxidase activity was approximately 60% of that of the wild-type plants. No difference in growth and appearance was observed between the mutant and the wild-type plants under normal conditions with ambient air under a light intensity of 100 µmol photons m-2 s-1. However, signs of severe damage, such as chlorosis and ion leakage from the tissue, rapidly appeared in mutant leaves in response to ozone treatment at a concentration of 0.2 µl l-1 under a higher light intensity of 350 µmol photons m-2 s-1 that caused no such symptoms in the wild-type plant. The mutant also exhibited sensitivity to sulfur dioxide and long-term high-intensity light. Arabidopsis mutants with deficiencies in other photorespiratory enzymes such as glutamate:glyoxylate aminotransferase and hydroxypyruvate reductase also exhibited ozone sensitivities. Therefore, photorespiration appears to be involved in protection against photooxidative stress caused by ozone and other abiotic factors under high-intensity light.

Faster Removal of 2-Phosphoglycolate through Photorespiration Improves Abiotic Stress Tolerance of Arabidopsis

“…The main function of the photorespiratory pathway is the efficient removal of critical intermediates, especially 2-PG, which severely inhibits carbon fixation and allocation [6,10]. Furthermore, it has been suggested that photorespiration plays a role in the abiotic stress response of plants [25][26][27]. Therefore, we hypothesized that an increased photorespiratory flux might facilitate plant abiotic stress tolerance.…”

“…Apart from the central role of photorespiration supporting photosynthetic CO 2 fixation, it has been suggested that it plays also a role in the stress response of plants. For example, malfunctioning of photorespiration leads to an enhanced susceptibility of the plants against pathogen attack [22,23], and lowered tolerance towards abiotic stresses [24][25][26][27]. This is mainly because photorespiration serves as alternative energy sink under unfavorable environmental conditions regenerating ADP and NADP and, thus, decreases acceptor limitation of the light process and related ROS formation [26,28,29].…”

Glutathione‐dependent denitrosation of GSNOR1 promotes oxidative signalling downstream of H2O2

“…Free and total SA concentrations were determined by high‐performance liquid chromatography–fluorescence as outlined in Han et al (). Glycolate content was measured by liquid chromatography–tandem mass spectrometry (Agilent), using 5% acetic acid extracts from leaves as described in Saji et al ().…”

Arabidopsis MLO2 is a negative regulator of sensitivity to extracellular reactive oxygen species

“…The level of sensitivity to O 3 within Arabidopsis is subject to natural genetic variation (Brosché et al, ). In addition, a number of induced mutants with enhanced O 3 sensitivity have been identified (Overmyer et al, ; Overmyer et al, ; Rao, Lee, & Davis, ; Saji et al, ; Saji et al, ; Vainonen & Kangasjärvi, ). These are defective in various physiological pathways that likely are interconnected functionally with each other (Overmyer et al, ).…”