The Arabidopsis ascorbate peroxidase 3 is a peroxisomal membrane-bound antioxidant enzyme and is dispensable for Arabidopsis growth and development

Abstract

Ascorbate peroxidase (APX) exists as several isoforms that are found in various compartments in plant cells. The cytosolic and chloroplast APXs appear to play important roles in antioxidation metabolism in plant cells, yet the function of peroxisomal APX is not well studied. In this study, the localization of a putative peroxisomal membrane-bound ascorbate peroxidase, APX3 from Arabidopsis, was confirmed by studying the green fluorescent protein (GFP)-APX3 fusion protein in transgenic plants. GFP-APX3 was found to co-localize with a reporter protein that was targeted to peroxisomes by the peroxisomal targeting signal 1. The function of APX3 in Arabidopsis was investigated by analysing an APX3 knockout mutant under normal and several stress conditions. It was found that loss of function in APX3 does not affect Arabidopsis growth and development, suggesting that APX3 may not be an important antioxidant enzyme in Arabidopsis, at least under the conditions that were tested, or the function of APX3 could be compensated by other antioxidant enzymes in plant cells.

Isozymes of antioxidative enzymes during ripening and storage of ber (Ziziphus mauritiana Lamk.)

“…Bernardi et al (2004) found young leaves of poplar to have two isozymes while mature leaves had only one. However, Narendra et al (2006) observed three isozymes of APX in Arabidopsis during growth and development.…”

Immobilized Subpopulations of Leaf Epidermal Mitochondria Mediate PENETRATION2-Dependent Pathogen Entry Control in Arabidopsis

“…We also aimed to generate analogous transgenic pen2 mutant plants producing GFP-tagged PEN2 protein that is exclusively localized tovperoxisomal membranes. To this end, we used the TAs of ASCORBATE PEROXIDASE3 (TA APX3 ) or MONODEHYDROASCORBATE REDUCTASE4 (TA MDAR4 ), which were recently described to provide exclusive targeting to peroxisomal membranes (Lisenbee et al, 2005;Narendra et al, 2006). However, all transgenic lines generated with these two different TAs showed promiscuous localization to both peroxisomes and mitochondria.…”

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

“…Recent data indicate that chloroplast-linked oxidative stress is mainly attributable to singlet oxygen rather than hydrogen peroxide (H 2 O 2 ; Triantaphylidès et al, 2008), while modeling showed that the chloroplast electron transport chain would have to devote a very high proportion of electrons to oxygen in order to meet the high rates of photorespiratory H 2 O 2 production in the peroxisomes (Noctor et al, 2002;Foyer and Noctor, 2003). Peroxisomal H 2 O 2 is notably metabolized by catalases, although ascorbate peroxidases are also associated with peroxisomes (del Río et al, 2006;Narendra et al, 2006;Nyathi and Baker, 2006). Catalasedeficient lines have been particularly useful in the analysis of oxidative stress responses (Takahashi et al, 1997;Willekens et al, 1997;Chamnongpol et al, 1998;Mittler et al, 1999;Rizhsky et al, 2002;Dat et al, 2003;Vandenabeele et al, 2004;Vanderauwera et al, 2005;.…”