Effects of Enhanced Ultraviolet-B Radiation on Physiological Characteristics of Nitrogen Metabolism in Cotton Seedlings(Gossypium hirsutum L.) |
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Authors: | WANG Yan LI Mao-Ying ZHANG Ming-Cai TAN Wei-Ming DUAN Liu-Sheng |
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Institution: | Engineering Research Center of Plant Growth Regulator, Ministry of Education /College of Agronomy and Biotechnology,China Agricultural University, Beijing 100193, China |
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Abstract: | The effects of ultraviolet-B (UV-B) radiation on the physiological characteristics of nitrogen metabolism were examined in two transgenic Bt cotton cultivars, 29317 and 29312, under hydroponic conditions. UV-B was artificially applied via filtered lamps at three levels: 0(CK), 2.7 and 5.4 kJ·m-2·d-1. Our results showed that UV-B radiation decreased shoot dry weight, but had no impact on root dry weight accumulation. At 2.7 kJ·m-2·d-1 UV-B radiation, no significant difference in total nitrogen content compared with the control was observed. However, high levels of UV-B radiation at 5.4 kJ·m-2·d-1 significantly increased the total nitrogen content. Further physiological studies revealed that UV-B radiation upregulated nitrate reductase activity, glutamine synthetase activity, protease activity, and peptidase activity. Higher contents of soluble protein and total free amino acids were induced by UV-B radiation. The results suggested that UV-B radiation promoted protein synthesis and degradation, which accelerated nitrogen metabolism in cotton seedlings. Enhanced nitrogen metabolism may be a protective response to UV-B radiation damage. |
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Keywords: | UV-B radiation cotton seedlings nitrogen metabolism |
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