关键词: 水稻, OsUreD, 脲酶, 氮素代谢

Abstract: The existence of urease activity in plant cells makes  hydrolize urea into ammonium that can be directly used by the plant. It has been reported that the activity of rice urease needs both the activation by nikel ion and co-ordination of three anncessory proteins i.e. UreD, UreG and UreF. In this work, the agronomic traits, nitrogen nutritional physiology and related enzymes’ activity were investigated in a rice Osured mutant, where Osured was deleted by a T-DNA insertion. This research revaled that during the seed germination of 1~7 d, the urease activity in the mutant remained relatively stable and 60%~80% lower than that of in wildtype (WT), but the activity of arginase increased by 30%~40% as compared to the WT. At the seeding- and tillering-stage, the mutant line exhibited an obvious growth inhibition with being small in size, e.g. lower plant-height and root length, reduction in tiller numbers,and reduced urease activity by 60%~90%. These results suggested that OsUreD encoding protein should be critical for rice urease activation. Nitrogen metabolic disorder associeted with alteration of the activity of urease and arginase in the Osured mutation might be an important molecular physiological factor responsible for the supression of rice growth and tillering.

Key words: rice, Osured, urease, nitrogen metabolism