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pH6.2左右。Westernblot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。
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 ^-- LN . 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.
出处
《中国水稻科学》
CAS
CSCD
北大核心
2007年第4期360-366,共7页
Chinese Journal of Rice Science
基金
国家自然科学基金重大项目(30390082)
