A Novel and Potentially Multifaceted Dehydroascorbate Reductase Increasing the Antioxidant Systems is Induced by Beauvericin in Tomato

Abstract

Dehydroascorbate reductases (DHARs) are important enzymes that reconvert the dehydroascorbic acid (DHA) into ascorbic acid (ASC). They are involved in the plant response to oxidative stress, such as that induced by the mycotoxin beauvericin (BEA). Tomato plants were treated with 50 µM of BEA; the main antioxidant compounds and enzymes were evaluated. DHARs were analyzed in the presence of different electron donors by native and denaturing electrophoresis as well as by western blot and mass spectrometry to identify a novel induced protein with DHAR activity. Kinetic parameters for dehydroascorbate (DHA) and glutathione (GSH) were also determined. The novel DHAR was induced after BEA treatment. It was GSH-dependent and possessed lower affinity to DHA and GSH than the classical DHARs. Interestingly, the mass spectrometry analysis of the main band appearing on sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) revealed a chloroplast sedoheptulose 1,7-bisphosphatase, a key enzyme of the Calvin cycle, and a chloroplast mRNA-binding protein, suggesting that the DHA reducing capacity could be a side activity or the novel DHAR could be part of a protein complex. These results shed new light on the ascorbate-glutathione regulation network under oxidative stress and may represent a new way to increase the plant antioxidant defense system, plant nutraceutical value, and the health benefits of plant consumption.

The Arbuscular Mycorrhizal Fungus Glomus viscosum Improves the Tolerance to Verticillium Wilt in Artichoke by Modulating the Antioxidant Defense Systems

“…The increased content of ASC observed in MI plants compared to I, along with the significant increase in MDHAR, corroborates the key role played by MDHAR in the regeneration of ASC from MDHA for ROS scavenging. Moreover, the regeneration of ASC from its oxidative state prevents the intracellular accumulation of DHA that, at high concentrations, has been proved to be toxic for cell metabolisms [78] and to inhibit the activity of enzymes regulated by the thioredoxin-thioredoxin system [79,80]. Our results suggest that MDHAR showed a higher specific activity than DHAR, as reported in previous studies [81][82][83].…”

Recent Developments in Enzymatic Antioxidant Defence Mechanism in Plants with Special Reference to Abiotic Stress

“…This novel DHAR is able to reduce DHA to ascorbate, although with a lower affinity to its substrates than the classical DHAR. In addition, it was revealed that novel DHAR is part of a larger protein complex and has a multifaceted role in the plant’s defence mechanism against stress [ 171 ]. Nonetheless, additional studies are needed to understand the role of different enzymes in the antioxidant mechanism.…”

Challenges and Opportunities of Light-Emitting Diode (LED) as Key to Modulate Antioxidant Compounds in Plants. A Review

“…The positive effect on the antioxidant compounds of vegetables has several implications, which go beyond the simple nutraceutical value of the food. An increased antioxidant capability endows the plants with a higher resistance towards harsh environmental conditions (excessive light, drought, extreme temperatures), toxic pollutants, and pathogens [ 107 , 227 ]. Indeed, many secondary metabolites have been shown to possess antimicrobial and antifungal properties [ 228 ].…”