• Molecules and Cells
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• 제27권2호
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• pp.129-134
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• 2009

Legume plants develop root nodules to recruit nitrogen-fixing bacteria called rhizobia. This symbiotic relationship allows the host plants to grow even under nitrogen limiting environment. Since nodule development is an energetically expensive process, the number of nodules should be tightly controlled by the host plants. For this purpose, legume plants utilize a long-distance signaling known as autoregulation of nodulation (AON). AON signaling in legumes has been extensively studied over decades but the underlying molecular mechanism had been largely unclear until recently. With the advent of the model legumes, L. japonicus and M. truncatula, we have been seeing a great progress including isolation of the AON-associated receptor kinase. Here, we summarize recent studies on AON and discuss an updated view of the long-distance control of nodulation.

• The Plant Pathology Journal
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• 제17권2호
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• pp.67-70
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• 2001

Medicago truncatula is a diploid legume plant related to the forage crop alfalfa. Recently, it has been chosen as a model species for genomic studies due to its small genome, self-fertility, short generation time, and high transformation efficiency. M. truncatula engages in symbiosis with nitrogen-fixing soil bacterium Rhizobium meliloti. M. truncatula mutants that are defective in nodulation and developmental processes have been generated. Some of these mutants exhibited altered phenotypes in symbiotic responses such as root hair deformation, expression of nodulin genes, and calcium spiking. Thus, the genes controlling these traits are likely to encode functions that are required for Nod-factor signal transduction pathways. To facilitate genome analysis and map-based cloning of symbiotic genes, a bacterial artificial chromosome library was constructed. An efficient polymerase chain reaction-based screening of the library was devised to fasten physical mapping of specific genomic regions. As a genomics approach, comparative mapping revealed high levels of macro- and microsynteny between M. truncatula and other legume genomes. Expressed sequence tags and microarray profiles reflecting the genetic and biochemical events associated with the development and environmental interactions of M. truncatula are assembled in the databases. Together, these genomics programs will help enrich our understanding of the legume biology.

• Applied Biological Chemistry
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• 제40권6호
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• pp.551-555
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• 1997

본 연구는 숙주특이적인 근류형성에 두과작물의 뿌리분비물에 포함된 기주특이적인 flavonoids와 근류균의 상호작용에 대해 실험하였다. Flavonoid 화합물에 대한 근류균의 생물학적 활성은 B. japonocum의 경우 대두의 뿌리분비물에 포함된 flavonoid화합물인 daidzein과 genistein에서는 생장 증진 효과가 나타났으며, alfalfa의 뿌리분비물에 포함된 flavonoid인 luteolin에서는 생장 저해 효과가 나타났으며, R. meliloti의 경우 luteolin의 경우 생장증진 효과가 나타났으며, daidzein과 genistein의 경우 생장저해효과가 나타났다. 각 근류균의 흡수 특이성은 B. japonicum에서 daidzein과 genistein이 각각 $14.95\;{\mu}g/g$와 $14.20\;{\mu}g/g$로 가장 높고 luteolin이 가장 낮게 나타났으며, R. meliloti의 경우 luteolin이 $18.31\;{\mu}g/g$으로 가장 높고 daidzein과 genistein이 가장 낮게 나타났다. 이와 같은 사실로 숙주특이적인 flavonoids가 근류균의 숙주특이성에 깊은 관련이 있을 것으로 사료된다.

• 미생물학회지
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• 제25권1호
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• pp.17-22
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• 1987

For the purpose of securing of strains which can be usefully utilized to study symbiosis between Rhizobium and legume plant, A. tumefaciens T7 was isolated and characterized and then subgroup biovar was determined. A. tumefaciens T7 induced smooth tumor like nopaline type one and did not grow at $37^{\circ}C$ and in the presence of 2% NaCl on yeast extract mannitol medium. The strain was able to grow on the New and Kerr selective media and utilize erythritol but not phenylalanine, tryptophan, and tartarate as a sole carbon source. Negative results were obtained from 3-keto-lactose production and oxidase test. The strain produced alkalifrom malonate and citrate and showed acid litmus milk reaction At least two large plasmids were detected in the cell lysate. According to all of these results, it could be concluded that subdivision of isolated strain was biovar 2.