In central Europe, soybean cultivation is gaining increasing importance to reduce protein imports from overseas and make cropping systems more sustainable. In the field, despite the inoculation of soybean with commercial rhizobia, its nodulation is low. In many parts of Europe, limited information is currently available on the genetic diversity of rhizobia and, thus, biological resources for selecting high nitrogen-fixing rhizobia are inadequate. These resources are urgently needed to improve soybean production in central Europe. The objective of the present study was to identify strains that have the potential to increase nitrogen fixation by and the yield of soybean in German soils. We isolated and characterized 77 soybean rhizobia from 18 different sampling sites. Based on a multilocus sequence analysis (MLSA), 71% of isolates were identified as Bradyrhizobium and 29% as Rhizobium. A comparative analysis of the nodD and nifH genes showed no significant differences, which indicated that the soybean rhizobia symbiotic genes in the present study belong to only one type. One isolate, GMF14 which was tolerant of a low temperature (4°C), exhibited higher nitrogen fixation in root nodules and a greater plant biomass than USDA 110 under cold conditions. These results strongly suggest that some indigenous rhizobia enhance biological nitrogen fixation and soybean yield due to their adaption to local conditions.

中文翻译：

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根瘤菌的表征用于改善中欧寒冷条件下的大豆种植


在中欧，大豆种植越来越重要，以减少从海外进口的蛋白质并使种植系统更具可持续性。在田间，尽管大豆接种了商业根瘤菌，但其结瘤率较低。在欧洲许多地区，目前有关根瘤菌遗传多样性的信息有限，因此用于选择高固氮根瘤菌的生物资源不足。迫切需要这些资源来提高中欧的大豆产量。本研究的目的是鉴定有潜力提高德国土壤中大豆固氮能力和产量的菌株。我们从 18 个不同的采样点分离并鉴定了 77 株大豆根瘤菌。根据多位点序列分析 (MLSA)，71% 的分离株被鉴定为慢生根瘤菌，29% 为根瘤菌。 nodD和nifH基因的比较分析未发现显着差异，这表明本研究中的大豆根瘤菌共生基因仅属于一种类型。一种耐低温 (4°C) 的分离株 GMF14 在寒冷条件下表现出比 USDA 110 更高的根瘤固氮作用和更高的植物生物量。这些结果强烈表明，一些本土根瘤菌由于适应当地条件而增强了生物固氮作用和大豆产量。