Impairment of peroxisomal APX and CAT activities increases protection of photosynthesis under oxidative stress. (12th October 2018)

• Record Type: Journal Article
• Authors: Sousa, Rachel H V; Carvalho, Fabricio E L; Lima-Melo, Yugo; Alencar, Vicente T C B; Daloso, Danilo M; Margis-Pinheiro, Marcia; Komatsu, Setsuko; Silveira, Joaquim A G
• Is Part Of: Journal of experimental botany. Volume 70:Number 2(2019)
• Page Start: 627
• Page End: 639
• Publication Date: 2018-10-12
• Subjects: Ascorbate peroxidase -- H2O2 signalling -- oxidative stress -- photosynthetic efficiency -- proteomics -- redox metabolism; Botany -- Periodicals; Botany, Experimental -- Periodicals; Plant physiology -- Periodicals; 580
• DOI: 10.1093/jxb/ery354
• Languages: English
• ISSNs: 0022-0957

Abstract

Abstract : Proteomics and physiological approaches reveal that peroxisomal APX silencing and CAT inhibition trigger H2 O2 -signalling for up-regulation of antioxidant proteins to protect the rice photosynthetic apparatus under oxidative stresss. Abstract: Retrograde signalling pathways that are triggered by changes in cellular redox homeostasis remain poorly understood. Transformed rice plants that are deficient in peroxisomal ascorbate peroxidase APX4 ( OsAPX4 -RNAi) are known to exhibit more effective protection of photosynthesis against oxidative stress than controls when catalase (CAT) is inhibited, but the mechanisms involved have not been characterized. An in-depth physiological and proteomics analysis was therefore performed on OsAPX4 -RNAi CAT-inhibited rice plants. Loss of APX4 function led to an increased abundance of several proteins that are involved in essential metabolic pathways, possibly as a result of increased tissue H2 O2 levels. Higher photosynthetic activities observed in the OsAPX4 -RNAi plants under CAT inhibition were accompanied by higher levels of Rubisco, higher maximum rates of Rubisco carboxylation, and increased photochemical efficiencies, together with large increases in photosynthesis-related proteins. Large increases were also observed in the levels of proteins involved in the ascorbate/glutathione cycle and in other antioxidant-related pathways, and these changes may be important in the protection of photosynthesis in the OsAPX4 -RNAi plants. Large increases in the abundance of proteins localized in the nuclei and mitochondria were also observed, together with increased levels of proteins involved in important cellular pathways, particularly protein translation. Taken together, the results show that OsAPX4 -RNAi plants exhibit significant metabolic reprogramming, which incorporates a more effective antioxidant response to protect photosynthesis under conditions of impaired CAT activity.