Changes of levels of glutamine synthetase isoforms in roots and leaves in response to nitrogen fertilizer application at different growth stages in irrigated rice |
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Authors: | Zhang Chufu Peng Shaobing John Bennett |
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Institution: | (1) College of Life Sciences, Wuhan University, 430072 Wuhan, China;(2) International Rice Research Institute, P.O. Box 933, 1099 Manila, Philippines |
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Abstract: | Nitrogen is a key element to control the growth and yield of crops. Fertilizer urea nitrogen (N) 60,45, and 30 kg/hm2 was applied at three different stages, midtillering, panicle initiation, and flowering, of the growth and development of
rice plants, respectively. At both midtillering and panicle initiation, the total activity of glutamine synthetase (GS) in
rice roots and leaves was incrased remarkably as a result of a large amount of ammonia absorbed by roots. Native-PAGE and
activity staining showed that the increase of total activity in rice roots and leaves was due to the synthesis of GSrb in
roots and GS2 in leaves and that the activity of GSra in roots and GS1 in leaves remained constant. The results showed that
the assimilation of external nitrogen was carried out by GSrb but not GSra in rice roots and that the activitry of GS2 was
induced also by the external nitrogen, and that GSrb played main role in meeting the needs of the rapid tillering for nitrogen.
At flowering, the activity of GS in rice roots and leaves did not change almost after topdressing. These rssults suggest that
the change of GS activity in rice roots may use as a measure of the utilization efficiency of the fertilizer.
Supported by the National Natural Science Foundation of China, Natural Science Foundation of Hubei Province, and International
Rice Institute, P. O. Box 933 1099 Manila, Philippines
Zhang Chufu: born in 1946, Professor, to whom Correspondence should be addressed |
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Keywords: | glutamine synthetase isoform rice nitrogen |
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