Fig. 2

Effects of prolonged UV-B stress on photosynthesis-related pigments and ultrastructure of chloroplast in Nβ and Sβ seedlings. Measurement of pigment contents: A Chlorophyll a (Chl a), B chlorophyll b (Chl b), C total chlorophyll, and D carotenoids (Caro) in Nβ and Sβ plants under non-stress and stress conditions. E Ultrastructure of the chloroplasts of Nβ and Sβ plants under non-stress and UV-B stress, showing more disintegration of grana stacks in Nβ under stress conditions. Data are shown as means of three independent experiments and different letters showing significant differences (P < 0.05) within the same treatment (Nβ^ns vs. Sβ^ns and Nβ^uvs vs. Sβ^uvs). Lines with asterisks indicate significant differences between non-stress and UV-B stress conditions of the same plants (Nβ^ns vs. Nβ^uvs and Sβ^ns vs. Sβ^uvs), as determined by Student’s t test (*P < 0.05, **P < 0.01)