Photorespiratory Metabolism: Genes, Mutants, Energetics, and Redox Signaling

Abstract

Photorespiration is a high-flux pathway that operates alongside carbon assimilation in C(3) plants. Because most higher plant species photosynthesize using only the C(3) pathway, photorespiration has a major impact on cellular metabolism, particularly under high light, high temperatures, and CO(2) or water deficits. Although the functions of photorespiration remain controversial, it is widely accepted that this pathway influences a wide range of processes from bioenergetics, photosystem II function, and carbon metabolism to nitrogen assimilation and respiration. Crucially, the photorespiratory pathway is a major source of H(2)O(2) in photosynthetic cells. Through H(2)O(2) production and pyridine nucleotide interactions, photorespiration makes a key contribution to cellular redox homeostasis. In so doing, it influences multiple signaling pathways, particularly those that govern plant hormonal responses controlling growth, environmental and defense responses, and programmed cell death. The potential influence of photorespiration on cell physiology and fate is thus complex and wide ranging. The genes, pathways, and signaling functions of photorespiration are considered here in the context of whole plant biology, with reference to future challenges and human interventions to diminish photorespiratory flux.

Peroxisomal Hydrogen Peroxide Is Coupled to Biotic Defense Responses by ISOCHORISMATE SYNTHASE1 in a Daylength-Related Manner

“…A role for peroxisomal H 2 O 2 in pathogen responses is consistent with studies of mutants for Ser:glyoxylate aminotransferase (Taler et al, 2004), an enzyme immediately downstream of glycolate oxidase in the photorespiratory pathway, as well as effects of photorespiratory conditions on the phenotypes of the lsd1 mutant (Mateo et al, 2004). Given the high catalase activities of wild-type plants, it is likely that this enzyme must be down-regulated to allow H 2 O 2 produced in leaf peroxisomes to contribute to signaling during a biotic challenge (Foyer et al, 2009). Several mechanisms by which this could occur have been described.…”

Serine Acts as a Metabolic Signal for the Transcriptional Control of Photorespiration-Related Genes in Arabidopsis

“…While the biochemistry and function of photorespiration are rather well understood (Foyer et al, 2009;Bauwe et al, 2010Bauwe et al, , 2012, not very much is known about the regulation of photorespiration (Fernie et al, 2012). This process is intimately linked to photosynthesis, where diurnal regulation has been known for many years (Buchanan, 1980;Servaites, 1994a, 1994b;Bläsing et al, 2005).…”

“…Similar patterns were observed for mRNA levels of other photorespiratory enzymes, for example Glycine Decarboxylase (GDC), Serine Hydroxymethyltransferase1 (SHM1), and peroxisomal Hydroxypyruvate Reductase1 (HPR1; Kim et al, 1991;Sloan et al, 1993;Srinivasan and Oliver, 1995;McClung et al, 2000;Lutziger and Oliver, 2001). More comprehensive transcript profilings revealed that light induction is a general feature of most photorespiratory genes (Foyer et al, 2009). Interestingly, it has been reported that light not only affects the level but also the subcellular distribution of HPR1 mRNA in pumpkin (Cucurbita maxima) leaves by an alternative splicing mechanism (Mano et al, 1999).…”

Geração e desintoxicação enzimática de espécies reativas de oxigênio em plantas

“…A geração fotorrespiratória de H 2 O 2 ocorre como subproduto da oxidação do grupo alcoolico do glicolato (FOYER et al, 2009). Em folhas, a produção de H 2 O 2 nos peroxissomos e clorosplastos pode ser de 30 a 100 vezes mais rápida do que nas mitocôndrias (FOYER & NOCTOR, 2003;BHATTACHARJEE, 2010).…”