不同形态氮素培养下水稻叶片中蛋白质差异表达

硝态氮除作为主要氮源外，还作为一种潜在的信号物质，在植物生长发育过程中起着重要作用，其作用方式的直接性或间接性近年来成为了研究热点。利用双向电泳（2-DE）技术，对不同形态氮素（NO3^-与NH4^＋）培养的水稻叶片蛋白表达谱进行了比较分析，结果在硝态氮和铵态氮培养的叶片中分别分辨出26个和6个增量表达蛋白。质谱分析结合数据库检索鉴定出11个蛋白，其中7个硝态氮上调的蛋白为：光系统Ⅱ放氧复合蛋白1（N1）、抗性相关蛋白MLA13（N2）、光系统Ⅱ23kD多肽（N3）、翻译激活因子（N5）、光系统Ⅱ放氧复合蛋白2前体（N8）、未知蛋白（N17）和泛素载体蛋白（N18）；4个铵态氮上调蛋白为：ATP合酶β亚基（A1）、转氨酶（A3）和两个功能未知的蛋白（A5，A6）。上述研究结果有助于了解水稻适应不同氮素营养时的生物化学基础及可能的生物学意义，同时也为深入阐明水稻响应NO3^-与NH4^＋信号的反应提供了蛋白水平的证据。

Differential Expression of Proteins in Rice Leaves Cultivated with Different Forms of Nitrogen Nutrients

Nitrate as one of the two main nitrogen source compounds, acts also as a potent signal substance in plant growth and development. It is increasingly interesting to determine whether nitrate itself or the derived metabolites acts as a signal during the regulation. Rice seedlings were treated with different nitrogen forms (NO(-)(3) vs. NH(+)(4)) and total proteins extracted either from nitrate-fed or ammonium-fed leaves were separated by two-dimensional gel electrophoresis (2-DE), and then the differentially-expressed proteins were identified by MALDI-TOF-MS or ESI-Q-TOF-MS. Twenty-six proteins were up-regulated with NO(-)(3) as the nitrogen source while 6 were up-regulated with NH(+)(4) as the nitrogen source. MS analysis, in combination with database searching, allowed for only a total of 11 proteins identified with significant probability. Among them 7 nitrate-up-regulated proteins were identified, i.e., a PSII oxygen-evolving complex protein 1 (N1), a putative CC-NBS-LRR resistance protein MLA13 (N2), a 23-kD polypeptide of PSII (N3), a translation initiation factor eIF-5A (N5), a putative PSII oxygen-evolving complex protein 2 precursor (N8), an unknown protein (N17), and the ubiquitin carrier protein UBC7 (N18). Four ammonium-up-regulated proteins were identified as the ATP synthase beta subunit (A1), the putative aminotransferase (A3), a hypothetical protein (A5), and OSJNBb0032K15.22 (A6). These results give some new insights into both the biochemical adaptation of plant to different nitrogen forms (NO(-)(3)/NH(+)(4)) and the differences in responses signaled by NO(-)(3)/NH(+)(4) in rice.