Institute of Global Innovation Research (GIR), Tokyo University of Agriculture and Technology.
Leibniz Centre for Agricultural Landscape Research (ZALF).
Microbes Environ. 2020;35(1). doi: 10.1264/jsme2.ME19124.
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.
在中欧，大豆种植的重要性日益增加，这不仅可以减少从海外进口的蛋白质，还可以使种植系统更加可持续。然而，尽管在田间接种了商业根瘤菌，但大豆的结瘤率仍然很低。在欧洲的许多地区，目前关于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也不足。这些资源对于提高中欧地区的大豆产量是迫切需要的。本研究的目的是鉴定出具有在德国土壤中增加固氮和大豆产量潜力的菌株。我们从 18 个不同的采样点分离并鉴定了 77 株大豆根瘤菌。基于多位点序列分析（MLSA），71%的分离株被鉴定为慢生根瘤菌，29%的分离株被鉴定为根瘤菌。对 nodD 和 nifH 基因的比较分析表明，没有显著差异，这表明本研究中的大豆根瘤菌共生基因仅属于一种类型。一个分离株 GMF14 对低温（4°C）具有耐受性，在低温条件下，其根瘤中的固氮能力和植物生物量比 USDA 110 更高。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和大豆产量。
