Investigation of supplemental ultraviolet-B-induced changes in antioxidative defense system and leaf proteome in radish (Raphanus sativus L. cv Truthful): an insight to plant response under high oxidative stress.

Impact of supplemental UV-B (sUV-B) has been investigated on photosynthetic pigments, antioxidative enzymes, metabolites, and protein profiling of radish plants under realistic field conditions. Exposure of sUV-B leads to oxidative damage in plants. However, plants possess a number of UV-protection mechanisms including a stimulation of antioxidant defense system. It caused alteration in reactive oxygen species metabolism primarily by decreasing catalase activity vis-à-vis enhanced activities of other enzymatic (superoxide dismutase, ascorbate peroxidase, and glutathione reductase) and non-enzymatic (ascorbic acid) antioxidants. Qualitative analysis of samples also showed significant reductions in photosynthetic pigments and protein content. After sUV-B exposure, protein profile showed differences mainly at eight points--126.8, 84.8, 71.9, 61.5, 47.8, 40.6, 38.9, and 17.5 kDa, whereas protein(s) of 38.9 kDa showed increment. Results of the present investigation clearly showed the adverse effect of sUV-B on total biomass at final harvest.