2-oxoglutarate-dependent dioxygenases: A renaissance in attention for ascorbic acid in plants

Abstract

L-Ascorbic acid (ascorbate, Vitamin C) is an essential human micronutrient that is predominantly obtained from plants. It is known to work as the major antioxidant in plants, and it underpins several environmentally induced stresses due to its use as a co-factor by certain 2-oxoglutarate-dependent (2-OG) dioxygenases [2(OG)-dioxygenases]. It is important to understand the role of 2(OG)-dioxygenases in the biosynthesis of ascorbate. The present study examined contents of ascorbate and protein-protein interaction in nine T-DNA mutants of Arabidopsis containing an insert in their respective (2-OG) dioxygenase genes (At1g20270, At1g68080, At2g17720, At3g06290, At3g28490, At4g35810, At4g35820, At5g18900, At5g66060). In this study, the amount of ascorbate in five of the mutants was shown to be almost two-fold or more than two-fold higher than in the wild type. This result may be a consequence of the insertion of the T-DNA. The prediction of possible protein interactions between 2(OG)-dioxygenases and relevant ascorbate-function players may indicate the oxidative effects of certain dioxygenase proteins in plants. It is expected that certain dioxygenases are actively involved in the metabolic and biosynthetic pathways of ascorbate. This involvement may be of importance to increase ascorbate amounts in plants for human nutrition, and to protect plant species against stress conditions.

The Function of Ascorbic Acid through Occam’s Razor: What We Know, What We Presume and What We Hope For

“…The more AsA is oxidized, the less AsA is available for the reactions catalyzed by 2-ODDs. This is indirectly confirmed by the observed correlation between the inactivation of some 2-ODD coding genes and higher AsA content in Arabidopsis insertion mutants [95]. In this perspective, AsA is at the same time the sensor of stress conditions and the activator of downstream responses via 2-ODDs.…”

Underlying mechanisms of FHB susceptibility and resistance in wheat: Insights from a transcriptome‐based analysis

“…Consistent with what has been observed in other hemibiotrophic pathogens such as Colletotrichum graminicola in maize (Torres et al., 2016; Vargas et al., 2012) and Zymoseptoria tritici in wheat (Keon et al., 2007; O'Driscoll et al., 2014), the genes highly upregulated in response to Fg at 48 hpi in AAC Tenacious are those associated with maintenance of redox state homeostasis and suppression of PCD (Table 1). L‐gulonolactone oxidase ( TraesCS7A02G317500 ) and 2(OG)‐dioxygenases ( TraesCS5B02G224900 ) are both involved in biosynthesis of ascorbate, which acts as an ROS scavenger and improves the tolerance of plants against stressful conditions by regulating levels of cellular ROS under stress conditions (Figure 3; Huang et al., 2019; Mahmood & Dunwell, 2020; Paciolla et al., 2019). GSTs are also known for their roles in maintaining the physiological redox state of the cell and protection of the cell against oxidative damage (Dubreuil‐Maurizi & Poinssot, 2012).…”

Multiple Physiological and Biochemical Functions of Ascorbic Acid in Plant Growth, Development, and Abiotic Stress Response

“…The reversible oxidation of AsA plays an indispensable bioactive role in maintaining the active center of the 2-oxoglutarate/Fe (II)-dependent dioxygenase (2-ODD), a large-class protein family in plants that participates in hydroxylation, desaturation, and demethylation throughout the entire stages of plant growth, development, fruit ripening, and abiotic stress response [7][8][9] (Table 1). These reactions are required to control proteostasis and regulate chromatin accessibility, which explains AsA's dominance in cellar homeostasis [8].…”