高级植物生理学 课件 第5章 植物钾营养分子生理.ppt

第六章 植物钾营养分子生理 Zichao Mao mzcleemao@ Why potassium is important Potassium (K) play key roles in physiological and biochemical processes, which greatly influence the growth and development of plants. Particular physiological processes affected substantially by inadequate supply of K (1) partitioning of carbohydrates between roots and shoots; (2) photosynthetic carbon metabolism; (3) formation of reactive O2 species and related photooxidation; (4) regulation of stomatal activity and water regime; (5) tolerance against biotic and abiotic stress factors, such as salt stress and drought stress. 1．钾离子是植物细胞中含量最丰富的阳离子之一。它的功能： K+能促进细胞内酶的活性。细胞内有50多种酶或完全依赖于K+ ，或受K+的激活，如丙酮酸激酶、谷胱合成酶、6-磷酸果糖激酶等能被K+激活。作用方式为：同其他一价阳离子都是通过诱导酶构象的改变，使酶得到活化，从而提高催化反应的速率。在某些情况下K+能增加酶对底物的亲和力。K+对膜结合ATP酶也有激活作用。 2.K+与蛋白质的合成有关。小麦胚芽中分离出的核糖体，合成蛋白质达到最佳速率时，其所需K+浓度为130mM。 3 ． K+可能参与tRNA与核糖体结合过程中的几个步骤。 Mineral nutrition of plants Plants need elements other than C to grow and develop Must integrate carbon with other inorganic minerals taken up by roots from environment Together, these elements are the building blocks of complex molecules (proteins, nucleic acids, etc.) Mineral (inorganic) nutrition dependent on C metabolism and vice-versa Need for understanding how plants gain nutrition from environment People no longer grew their own food! Need to optimize growth conditions to feed more people central role of NPK fertilizer to boost yield Hydroponic growth facilitated the discovery of essential mineral nutrients Further definition of “essential”: Sachs (mid-19th century) used hydroponic culture now used for vegetable production roots are cultured in solution, not in soil More modern growth media Hoagland’s solution → now slightly MODIFIED Murashige and Skoog (M + S) Solutions have high nutrient levels relative to soil Required because the supply is often not replenished frequently Hydroponic culture can be as simple as a plant supported in an aerated pot If roots waterlogged, what happens to yield? Hydro