Explication of speciffic function of crop root system components differing in development and anatomy

作物的根系由发育和解剖特征不同的根组成。本研究旨在探讨这些根系的功能差异。首先，我们发现，在水稻根系中，除了常规的发育分析外，量化根系结构复杂性的分形分析和量化分枝格局的拓扑分析对于刻画根系结构是非常有效的。在根中，特别是侧根对土壤水分条件和培养条件的变化有很强的反应能力。碳、氮动态以及琥珀酸脱氢酶和过氧化物酶活性随年龄的变化表明，种子根轴及其侧根的衰老模式不同。在内源脱落酸和玉米素核苷的动态变化上也存在差异。对几种食用豆科植物根系结构的研究表明，…的遗传变异氮素的存在主要是侧根发育所致，不同生长条件下的主根伸长生长表现出可塑性。在花生根系中，丛枝菌根主要在侧根上形成，而在主根轴上很少形成。在这些侧根上，菌根菌落的出现在顶端增加，特别是在主根轴近端开始的相对老化的根中。此外，菌根的形成通过侧根的发育改变了根系的形态，其中1级和2级侧根的反应不同。因此，本研究通过对根系成员年龄的表征，发现根之间存在着对各种环境因素的发育反应、代谢和生理活性以及与菌根真菌的亲和力等功能差异，它们通过发挥特定的作用而对整个根系的整体功能做出贡献。较少

A crop root system consists of roots differing in developmental and anatomical features. This study aimed to examine functional difference among those roots.First, we showed that in rice root system, in addition to the conventional developmental analysis the fractal analysis that quantifies the complexity of root system structure and the topological analysis that quantifies the branching pattern are quite effective for characterizing root system structure. Then, among the roots, rspecially lateral roots were shown to sharply respond to the changes in moisture conditions in soil and culture conditions in vitro. Carbon and nitrogen dynamics, and changes in succinic dehydrogenase and peroxidase activity with aging indicated that seminal root axis and its lateral roots differ in aging pattern. The differences were also found in the dynamics of endogenous abscisic acid and zeatin riboside. An examination of root system structure for several food legume species revealed that genetic variatio … More n exists mainly due to lateral root development, and their taproot elongation growth exhibits plasticity when grown under different conditions. In a peanut root system, arbuscular mycorrhiza was formed mostly on lateral roots, but scarcely on taproot axis. On those lateral roots, the mycorrhizal colony occurrence increased acropetally especially in relatively aged roots that initiated on the proximal portion of the taproot axis. Further, the formation of mycorrhiza altered root system morphology through lateral root development, where the responses differed between 1st and 2nd order lateral roots.As such, through characterizing root members in a root system with a special attention to their ages, this study showed that the functional differences exist among the roots such as developmental response to various environmental factors, metabolic and physiological activity, and affinity with mycorrhizal fungus, and they contribute to the overall function of an entire root system by playing their specific roles. Less