Abstract:

In order to investigate the possible role of silicon in rice (Oryza sativa L.) leaves resistance to ultraviolet-B (UV-B), experiments were conducted by using rice plants solution-cultured with or without silicon supplementation. Results showed that under high UV-B irradiation the silicon-deficient leaves exhibited obvious brown spots and strips of UV damage symptoms, but the silicon-treated leaves were not affected. A 21% and 67% increase in soluble and insoluble UV-absorbing compounds was observed in the epidermis of silicon-treated leaves, respectively. Furthermore, fluorescence microscopy revealed that a great deal of insoluble UV-absorbing compounds was enriched in silicon bodies that were formed in the cell walls and cell lumina of epidermis of silicon-treated leaves, whereas the insoluble UV-absorbing compounds were less in the epidermis of non-silicon-treated leaves. Based on these results, it is concluded that the elevated UV resistance of silicon-treated leaves is due to the increase of phenolic compounds in epidermis induced by silicon.

Key words: rice (Oryza sativa), ultraviolet-B, phenolic compounds, silicon