Effects of light on cyanide‐resistant respiration and alternative oxidase function in Arabidopsis seedlings

Abstract

Mitochondrial alternative oxidase (AOX), the unique respiratory terminal oxidase in plants, catalyzes the energy wasteful cyanide (CN)-resistant respiration and plays a role in optimizing photosynthesis. Although it has been demonstrated that leaf AOX is upregulated after illumination, the in vivo mechanism of AOX upregulation by light and its physiological significance are still unknown. In this report, red light and blue light-induced AOX (especially AOX1a) expressions were characterized. Phytochromes, phototropins and cryptochromes, all these photoreceptors mediate the light-response of AOX1a gene. When aox1a mutant seedlings were grown under a high-light (HL) condition, photobleaching was more evident in the mutant than the wild-type plants. More reactive oxygen species (ROS) accumulation and inefficient dissipation of chloroplast reducingequivalents in aox1a mutant may account for its worse adaptation to HL stress. When etiolated seedlings were exposed to illumination for 4 h, chlorophyll accumulation was largely delayed in aox1a plants. We first suggest that more reduction of the photosynthetic electron transport chain and more accumulation of reducing-equivalents in the mutant during de-etiolation might be the main reasons.

Mitochondrial Alternative Oxidase Maintains Respiration and Preserves Photosynthetic Capacity during Moderate Drought in Nicotiana tabacum

“…Such studies comparing the Arabidopsis wild type and aox1a plants have, in general, demonstrated modest perturbations of A n and/or Chl fluorescence parameters (Zhang et al, 2010;Florez-Sarasa et al, 2011;Yoshida et al, 2011b;Gandin et al, 2012;Vishwakarma et al, 2014). The results are consistent with there being little if any perturbation of respiration rate in the Arabidopsis aox1a plants (see the introduction), albeit only R D rates (not R L ) have been reported thus far.…”

“…In recent years, the potential importance of specifically AOX respiration during photosynthesis has been examined using the Arabidopsis aox1a plants (Giraud et al, 2008;Strodtkötter et al, 2009;Zhang et al, 2010;Florez-Sarasa et al, 2011;Yoshida et al, 2011aYoshida et al, , 2011b. In general, these studies reported small perturbations of photosynthesis in standard-grown aox1a plants, including slightly lower rates of CO 2 uptake or O 2 release (Gandin et al, 2012;Vishwakarma et al, 2014), slightly higher rates of cyclic electron transport (CET; Yoshida et al, 2011b), and slightly increased susceptibility to photoinhibition after a high light treatment (FlorezSarasa et al, 2011).…”

Expression and signal regulation of the alternative oxidase genes under abiotic stresses

“…Among these AOX genes, AOX1a is the most intensively studied and is the most responsive to stress. In Arabidopsis, this gene is induced by most abiotic stresses including drought, chilling, high salt, high light, and limitation of nitrogen [4,6,23,40,41]. Furthermore, using transgenic A. thaliana with varying expression levels of AOX1a, it demonstrated that the induction of AOX1a under abiotic stresses is actually associated with the tolerance of plants.…”

Alternative Oxidase in Resistance to Biotic Stresses: Nicotiana attenuata AOX Contributes to Resistance to a Pathogen and a Piercing-Sucking Insect But Not Manduca sexta Larvae

“…Abiotic stresses such as drought (Bartoli et al, 2005), high salt (Costa et al, 2007;Feng et al, 2010a), low temperature (Vanlerberghe and McIntosh, 1992;Popov et al, 2011;Wang et al, 2011), and wounding (Hiser and McIntosh, 1990) are known to stimulate the activity of alternative respiratory pathways or at least increase AOX transcripts and/or protein levels. Phytochrome, phototropin, and cryptochrome photoreceptors have been shown to mediate the light-responsiveness of the AOX1a gene in Arabidopsis (Arabidopsis thaliana) seedlings, and aox1a mutants showed increased photobleaching damage under high light conditions (Zhang et al, 2010). Several studies have indicated that AOX may also function in resistance to biotic stress such as infection by pathogens.…”