Co-Investigator(Kenkyū-buntansha) |
YANO Katsuya Nagoya University, School of Agricultural Sciences, Asst.Prof., 農学部, 助手 (00283424)
IIJIMA Morio Nagoya University, School of Agricultural Sciences, Asst.Prof., 農学部, 助手 (60252277)
KONO Yasuhiro Nagoya University, School of Agricultural Sciences, Prof.Emer., 農学部, 名誉教授 (90023407)
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Research Abstract |
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
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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
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