Ascorbate as seen through plant evolution: the rise of a successful molecule?

Abstract

Ascorbate is a widespread and efficient antioxidant that has multiple functions in plants, traditionally associated with the reactions of photosynthesis. This review aims to look at ascorbate from an evolutionary perspective. Cyanobacteria, algae, and bryophytes contain lower concentrations of ascorbate than higher plants, where the molecule accumulates in high concentrations in both photosynthetic and non-photosynthetic organs and tissues. This increase in ascorbate concentration is paralleled by an increase in the number of isoforms of ascorbate peroxidase and the ascorbate regenerating enzymes mono- and dehydroascorbate reductase. One way of understanding the rise in ascorbate concentrations is to consider ascorbate as a molecule among others that has been subject to selection pressures during evolution, due to its cost or benefit for the cell and the organism. Ascorbate has a low cost in terms of synthesis and toxicity, and its benefits include protection of the glutathione pool and proper functioning of a range of enzymes. The hypothesis presented here is that these features would have favoured increasing roles for the molecule in the development and growth of multicellular organisms. This review then focuses on this diversity of roles for ascorbate in both photosynthetic and non-photosynthetic tissues of higher plants, including fruits and seeds, as well as further functions the molecule may possess by looking at other species. The review also highlights one of the trade-offs of domestication, which has often reduced or diluted ascorbate content in the quest for increased fruit growth and yield, with unknown consequences for the corresponding functional diversity, particularly in terms of stress resistance and adaptive responses to the environment.

Ascorbate biosynthesis and its involvement in stress tolerance and plant development in rice (Oryza sativa L.)

“…Certain organs of higher plants contain relatively high concentrations of AsA, which constantly increased during the evolution of plants in line with an expansion of the functions in the plant metabolism (Gest et al 2013). AsA is primarily considered as an antioxidant (Smirnoff and Pallanca 1996), due to its ability to scavenge reactive oxygen species (ROS) through enzymes of the ascorbate-glutathione cycle involving the enzyme ascorbate peroxidase, or non-enzymatically by reducing H 2 O 2 directly to water (Noctor and Foyer 1998).…”

Interaction of ascorbate with photosystem I

“…Concentrations of ascorbate in plant tissues and different organelles of the plant cell (including chloroplasts of C 3 plants) are rather high (up to 20-50 mM), depending on species and plant cultivation conditions (Foyer et al 1983;Law et al 1983;Smirnoff 1996;Eskling and Akerlund 1998;Gest et al 2013). Ascorbate is an antioxidant indispensable for plant cell defense against reactive oxygen species (ROS).…”

Evaluation of Biochemical Marker - Glutathione and DNA Fingerprinting of Biofield Energy Treated <i>Oryza sativa</i>

“…To fight and maintain a steady-state level against ROS, plants itself can evolve several antioxidant enzymes including GSH. It helped to scavenge the excessive ROS through redox-homeostatic mechanism [27][28][29]. More generation of ROS impart intrinsic metabolism in plant cell negatively [30].…”