NaCl induced cross-acclimation to UV-B radiation in four Barley (Hordeum vulgare L.) cultivars

摘要

The effect of pre-treatment with 200 ixiM NaCl on the response of four barley cultivars (Hordeum vulgare L. cv. Bulbul-89, Kalayci-97, Tarm-92 and Tokak-157/37) to UV-B radiation was investigated. Salt stress as well as UV-B irradiation led to a decrease of the total chlorophyll (chl) content in all cultivars, except in Kalayci-97. While carotenoids are almost not affected by NaCl treatment, UV-B irradiation caused an increase by 5-20% of carot-enoid content of all cultivars. UV-B induced damages ofphotosynthetic apparatus were estimated by the rate of photosynthetic electron transport measured by chl fluorescence and the rate of oxygen evolution, the latter being more affected. Pre-treatment with NaCl alleviated harmful effect of UV-B irradiationon F_v/ F_m and ETR, but not on oxygen evolution. UV-B-induced and UV-B-absorbing compounds with absorption at 300 and 438 nm increasedas a result of UV-B treatment. The level of stress marker proline increased considerably as a result of NaCl treatment, while UV-B irradiation resulted in a pronounced increase of the level of H_2O_2. MDA enhanced in the seedlings subjected to salt and UV-B stress. Established cross-acclimation to UV-B as a result of salt treatment could be due to the increased free proline and the level of UV-B absorbing compounds in barley seedlings subjected to NaCl.