The mycotoxins beauvericin and T-2 induce cell death and alteration to the ascorbate metabolism in tomato protoplasts

The phytotoxicity of the mycotoxins from Fusarium spp. beauvericin and T-2 toward tomato protoplasts was evaluated. Both toxins caused protoplast death, but the phytotoxicity of beauvericin was much more severe in terms of reduction in protoplast viability. The possible involvement of the ascorbate system in the response induced by the two mycotoxins was also studied. Tomato protoplast death was preceded by an imbalance of the ascorbate system, which was diversely affected by the two mycotoxins. Beauvericin caused a decrease in the ascorbate level, whereas T-2 induced a significant increase in dehydroascorbate. The changes in the activity of ascorbate peroxidase, the most efficient scavenger of hydrogen peroxide in plant cells present in all cell compartments, were also analysed. Ascorbate peroxidase activity decreased after 3 h of treatment with beauvericin. The activity of dehydroascorbate reductase, the enzyme involved in ascorbate regeneration from its oxidized form, also increased within the first hour of treatment. T-2 treatment did not induce significant changes in either ascorbate peroxidase or dehydroascorbate reductase activities. The possible role of the ascorbate system in tomato protoplast death induced by treatment with beauvericin and T-2 mycotoxins is discussed