Fine structural effects of UV radiation on leaf tissue of Beta vulgaris

Abstract

The effect of UV radiation was studied at the ultra structural level using treated and untreated leaf material from Beta vulgaris L. cv. Primahill. Although interest was centered mainly on changes resulting from treatment with UV-B radiation (280–320 nm), UV-C radiation (<280 nm) was included as an indicator for severe damage. Among the more pronounced effects caused by UV-C irradiation were extreme damage to epidermal and subepidermal cells and extensive chloroplast disorganization. In addition, membrane-bound crystalloid inclusions were found where the cells were relatively undamaged. The more severe changes resulting from UV-B radiation were exemplified by disruptions in the chloroplast envelope, and while no crystalloid inclusions were found as in the UV-C treated tissue, a pronounced crystalloid formation of the stroma was seen in several sections from different leaves. Dilation of thylakoid membranes was discernible in tissue treated with UV-B or UV-C radiation.