Molecular and Physiological Studies of Nitrogen Uptake by Plants and Fungi

为了维持目前高水平的农业生产力，自1950年以来，全球氮肥的使用量增加了20倍以上，目前的用量约为每年1.4亿吨（1400亿公斤），成本约为700亿美元。除了经济方面的考虑，另一个问题是，施用的大部分氮肥通过挥发、反硝化和淋滤损失。例如，谷物只能回收施用氮的30 - 40%。因此，据估计，氮的使用效率适度提高1%将节省2.5亿美元（Raun和Johnson 1999）。从生态学的角度来看，肥料淋溶是湖泊和沿海水域富营养化的主要原因。例如，在墨西哥湾，大面积的沿海水域现在缺氧，造成大量鱼类死亡。因此，有必要提高氮的利用效率。我的研究旨在确定植物根系吸收硝酸盐肥料的过程。自生物学研究开始以来，营养物质跨细胞膜的运输一直是纯科学家和应用科学家最感兴趣的过程。它仍然是一个深入研究的课题。从更实用的角度来看，只有更好地理解这一基本过程，才有可能提高全球和当地的作物产量，同时提高植物对施用肥料的利用效率。这项研究在经济和环境方面的影响是深远的，特别是对发展中国家。

In order to sustain current high levels of agricultural productivity, global application of nitrogen fertilizers has risen greater than 20 fold since 1950, to a current rate that is approximately 140 million tonnes (140 billion kg) per annum, at a cost of roughly seventy billion dollars U.S. In addition to this economic consideration, another problem is that the bulk of applied N fertilizer is lost through volatilization, denitrification and leaching. For example cereals recover only 30 to 40% of applied nitrogen. Therefore, it has been estimated that a modest 1% increase of N-use efficiency would save 250 million dollars (Raun and Johnson 1999). From an ecological perspective, fertilizer leaching is a major contributor to eutrophication of lakes and coastal waters. In the Gulf of Mexico, e.g. huge areas of coastal waters are now depleted of oxygen causing massive fish kills. Hence, there is every need to improve N-use efficiency. My research seeks to define the processes involved in nitrate fertilizer absorption by plant roots. The transport of nutrients across cell membranes is a process that has been of fundamental interest to both pure and applied scientists since the beginnings of biological study. It continues to be a subject of intense study. From a more applied perspective, only through better comprehension of this fundamental process will it be possible to improve crop yield globally and locally while achieving greater efficiency of plant use of applied fertilizer. The implications, of this research, both economically and environmentally are profound, especialy for developing countries.