Chinese Journal of Rice Science

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Response of Plasma Membrane H+-ATPase of Rice Root to Ammonium and Nitrate Nutrition

DI Ting-jun , ZHU Yi-yong , QIU Mei-hua , KAN Jian-luan , ZHANG Xiao-man , XU Guo-hua , SHEN Qi-rong
  

  • Received:1900-01-01 Revised:1900-01-01 Online:2007-07-10 Published:2007-07-10

水稻根系细胞膜H+ATPase对铵硝营养的响应差异

狄廷均1,2,朱毅勇1,2,*,仇美华1,阚建鸾1,张晓曼1,徐国华1,沈其荣 1   

  1. 1南京农业大学 资源与环境科学学院, 江苏 南京 210095; 2南京农业大学 Beckman Coulter合作示范实验室, 江苏 南京 210095;*通讯联系人, E-mail: yiyong1973@njau.edu.cn

Abstract: Rice plants(Oryza sativa L.ssp.japonica cv.Nanguang)were supplied with ammonium(NH4+-N)or nitrate(NO3--N)as sole nitrogen in hydroponics experiment and the plasma membrane vesicles of rice roots were isolated by a two-phase system at the seedling stage.The plasma membrane H+-ATPase hydrolytic activity was analyzed for elucidating the response of the plasma membrane H+-ATPase of rice root to ammonium or nitrate nutrition.The purity of plasma membrane isolated by the two-phase system was above 95%,which was suitable for analysis of H+-ATPase activity in plasma membrane. The hydrolytic activity, Km and Vmax of H+-ATPase in plasma membrane of rice root supplied with NH4+-N were markedly higher than those with NO3--N.The pH optimum of the plasma membrane H+-ATPase of rice root supplied with NH4+-N was 6.0,while it was about 6.2 for that with NO3--N. In addition,the Western blot showed that the enzyme concentration of plasma membrane H+-ATPase of rice root supplied with NH4+-N was higher than that with NO3--N.The results indicated that the higher activity of H+-ATPase in rice supplied with NH4+-N resulted from the increased amount of H+-ATPase units per membrane area.Furthermore,different H+-ATPase isoforms may exist in the roots of rice supplied with NH4+-N in comparison with NO3--N.It was suggested that the higher activity of plasma membrane H+-ATPase of rice root may be an adaptation mechanism to the NH4+-N nutrition.

Key words: rice, plasma membrane H+-ATPase, ammonium, nitrate, nitrogen nutrition, root

摘要: 用两相法分离了铵态氮(NH4+N)和硝态氮(NO3-N)营养下水稻苗期根系的细胞膜,并测定了细胞膜上H+ATPase的水解活性,以期阐明水稻根系细胞质膜上H+ATPase对不同氮素形态的响应差异。两相法分离的细胞膜纯度达到95%以上。在离体条件下,NH4+N营养的水稻根系细胞膜H+ATPase的水解活性和H+ATPase的Km和Vmax均显著高于NO3-N营养。NH4+N营养的水稻根系细胞膜H+ATPase最适pH值为6.0,而NO3-N营养的在pH 6.2左右。Western blot结果表明,NH4+N营养的水稻根系细胞膜H+ATPase浓度显著高于NO3-N营养的H+ATPase。说明NH4+N营养的水稻根系细胞膜H+ATPase活性高是因为单位细胞膜上的H+ATPase分子数量大于NO3-N营养,并且在NH4+N营养的水稻根系细胞膜上可能存在着与NO3-N营养不同的H+ATPase的同工酶。因此,NH4+N营养的水稻根系细胞膜H+ATPase活性高很可能是水稻根系对铵态氮营养的一种适应机制。

关键词: 水稻, 细胞质膜质子泵, 铵态氮, 硝态氮, 氮素营养, 根系