Kaiser Brent N, Gridley Kate L, Ngaire Brady Joanne, Phillips Thomas, Tyerman Stephen D
Discipline of Wine and Horticulture, School of Agriculture and Wine, University of Adelaide, PMB 1 Glen Osmond, South Australia 5064, Australia.
Ann Bot. 2005 Oct;96(5):745-54. doi: 10.1093/aob/mci226. Epub 2005 Jul 20.
The importance of molybdenum for plant growth is disproportionate with respect to the absolute amounts required by most plants. Apart from Cu, Mo is the least abundant essential micronutrient found in most plant tissues and is often set as the base from which all other nutrients are compared and measured. Molybdenum is utilized by selected enzymes to carry out redox reactions. Enzymes that require molybdenum for activity include nitrate reductase, xanthine dehydrogenase, aldehyde oxidase and sulfite oxidase.
Loss of Mo-dependent enzyme activity (directly or indirectly through low internal molybdenum levels) impacts upon plant development, in particular, those processes involving nitrogen metabolism and the synthesis of the phytohormones abscisic acid and indole-3 butyric acid. Currently, there is little information on how plants access molybdate from the soil solution and redistribute it within the plant. In this review, the role of molybdenum in plants is discussed, focusing on its current constraints in some agricultural situations and where increased molybdenum nutrition may aid in agricultural plant development and yields.
Molybdenum deficiencies are considered rare in most agricultural cropping areas; however, the phenotype is often misdiagnosed and attributed to other downstream effects associated with its role in various enzymatic redox reactions. Molybdenum fertilization through foliar sprays can effectively supplement internal molybdenum deficiencies and rescue the activity of molybdoenzymes. The current understanding on how plants access molybdate from the soil solution or later redistribute it once in the plant is still unclear; however, plants have similar physiological molybdenum transport phenotypes to those found in prokaryotic systems. Thus, careful analysis of existing prokaryotic molybdate transport mechanisms, as well as a re-examination of know anion transport mechanisms present in plants, will help to resolve how this important trace element is accumulated.
钼对植物生长的重要性与其在大多数植物中所需的绝对量不成比例。除了铜之外，钼是大多数植物组织中含量最少的必需微量营养素，并且常被用作比较和衡量所有其他营养素的基准。钼被特定的酶用于进行氧化还原反应。需要钼来发挥活性的酶包括硝酸还原酶、黄嘌呤脱氢酶、醛氧化酶和亚硫酸盐氧化酶。
钼依赖性酶活性的丧失（直接或间接通过内部钼水平低）会影响植物发育，特别是那些涉及氮代谢以及植物激素脱落酸和吲哚 - 3 - 丁酸合成的过程。目前，关于植物如何从土壤溶液中获取钼酸盐并在植物体内重新分配它的信息很少。在这篇综述中，讨论了钼在植物中的作用，重点关注其在一些农业情况下当前的限制以及增加钼营养可能有助于农业植物发育和产量的方面。
在大多数农业种植区，钼缺乏被认为是罕见的；然而，其表型常常被误诊，并归因于与其在各种酶促氧化还原反应中的作用相关的其他下游效应。通过叶面喷施钼肥可以有效补充内部钼缺乏并恢复钼酶的活性。目前对于植物如何从土壤溶液中获取钼酸盐或一旦进入植物体内后如何重新分配它的理解仍然不清楚；然而，植物具有与原核系统中发现的类似的生理钼转运表型。因此，仔细分析现有的原核钼酸盐转运机制，以及重新审视植物中已知的阴离子转运机制，将有助于解决这种重要微量元素是如何积累的问题。
