title: Temperature-Dependent Expression of NodC and Community Structure of Soybean-Nodulating Bradyrhizobia.
abstract: In order to assess the physiological responses of bradyrhizobia and competition for the nodulation of soybean at different temperatures, we investigated the expression of the nodC gene at 20, 25, and 30°C and the abilities of bacteria to nodulate soybean in microcosms at day/night cultivation temperatures of 23/18°C, 28/23°C, and 33/28°C for 16/8 h. We tested five Bradyrhizobium USDA strains: B. diazoefficiens USDA 110(T) and 122, B. japonicum USDA 123, and B. elkanii USDA 31 and 76(T). The expression of nodC was up-regulated by increasing culture temperatures in USDA 110(T), 122, 31, and 76(T), but was down-regulated in USDA 123. The proportions of USDA 110(T) and 122 within the community were the greatest at 28/23°C. The population of USDA 31 increased, whereas that of USDA 123 decreased with increasing cultivation temperatures. On the other hand, infection by USDA 76(T) was not detected, and low numbers of USDA 76(T) nodules confirmed its poor nodulation ability. These results indicate that the competitiveness of and infection by USDA 110(T), 122, 123, and 31 for soybean nodulation depend on cultivation temperatures, and suggest that the temperature dependence of nodC expression affects the bradyrhizobial community structure.
authors.affiliation: Faculty of Life and Environmental Science, Shimane University.
authors.forename: Sokichi
authors.initials: S
authors.lastname: Shiro
authors.forename: Chika
authors.initials: C
authors.lastname: Kuranaga
authors.forename: Akihiro
authors.initials: A
authors.lastname: Yamamoto
authors.forename: Reiko
authors.initials: R
authors.lastname: Sameshima-Saito
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Saeki
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis*; D058448:Biota / Q000528:radiation effects*; D020369:Bradyrhizobium / Q000145:classification* / Q000235:genetics* / Q000528:radiation effects; D015870:Gene Expression / Q000528:radiation effects*; D020869:Gene Expression Profiling; D017351:N-Acetylglucosaminyltransferases / Q000096:biosynthesis*; D055170:Plant Root Nodulation; D053204:Root Nodules, Plant / Q000382:microbiology; D013025:Glycine max / Q000382:microbiology*; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D017351:N-Acetylglucosaminyltransferases; C060771:NodC protein, Rhizobiales