Climate change models predict more frequent and prolonged drought events in Central Europe, which will exert extraordinary pressure on agroecosystems. One of the consequences is drought-related nutrient limitations for crops negatively affecting agricultural productivity. These effects can be mitigated by beneficial plant growth promoting rhizobacteria. In this study, we investigated the potential of cultivable bacterial species for phosphate solubilization in the rhizosphere of winter wheat at two relevant growth stages - stem elongation and grain filling stages. Rhizosphere samples were collected in the Global Change Experimental Facility in Central Germany, which comprises plots with conventional and organic farming systems under ambient and future climate. Phosphate-solubilizing bacteria were selectively isolated on Pikovskaya medium, phylogenetically classified by 16S rRNA sequencing, and tested for in vitro mineral phosphate solubilization and drought tolerance using plate assays. The culture isolates were dominated by members of the genera Phyllobacterium, Pseudomonas and Streptomyces. Cultivation-derived species richness and abundance of dominant taxa, especially within the genera Phyllobacterium and Pseudomonas, as well as composition of Pseudomonas species were affected by wheat growth stage. Pseudomonas was found to be more abundant at stem elongation than at grain filling, while for Phyllobacterium the opposite pattern was observed. The abundance of Streptomyces isolates remained stable throughout the studied growth stages. The temporal shifts in the cultivable fraction of the community along with considerable P solubilization potentials of Phyllobacterium and Pseudomonas species suggest functional redundancy between and among genera at different wheat growth stages. Phosphate-solubilizing Phyllobacterium species were assigned to Phyllobacterium ifriqiyense and Phyllobacterium sophorae. It is the first time that phosphate solubilization potential is described for these species. Since Phyllobacterium species showed the highest drought tolerance along all isolates, they may play an increasingly important role in phosphate solubilization in a future dryer climate.

中文翻译：

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小麦根际假单胞菌，链霉菌和毛状细菌群体之间的转移表明，在非生物胁迫下，小麦不同生育阶段的磷酸动员一致。

气候变化模型预测，中欧干旱事件将更加频繁和持续，这将对农业生态系统造成巨大压力。后果之一是与干旱有关的作物养分限制，对农业生产力产生负面影响。这些作用可以通过有益的植物生长促进根际细菌来减轻。在这项研究中，我们调查了可培养细菌物种在冬小麦根际中两个相关生长阶段（茎伸长和籽粒充实阶段）中磷酸盐增溶的潜力。根际样品是在德国中部的全球变化实验设施中收集的，该设施包括在环境和未来气候下使用常规和有机耕作系统的地块。在Pikovskaya培养基上选择性分离出可溶解磷酸盐的细菌，通过16S rRNA测序进行系统发育分类，并使用平板测定法测试其体外矿物质磷酸盐增溶和耐旱性。培养分离物主要由幽门杆菌属，假单胞菌属和链霉菌属成员组成。栽培阶段，特别是在毛状杆菌属和假单胞菌属中，来源于栽培种的物种丰富度和丰富度以及假单胞菌的种类组成都受到小麦生长阶段的影响。发现假单胞菌在茎伸长时比在籽粒灌浆时更丰富，而对于毛状芽孢杆菌则观察到相反的模式。在研究的整个生长阶段，链霉菌分离物的丰度保持稳定。群落可培养部分的时间变化以及巨大的幽门杆菌和假单胞菌种的磷增溶潜能表明不同小麦生长阶段属间和种间的功能冗余。将可溶解磷酸盐的根瘤菌属分为伊弗氏根瘤菌和槐属根瘤菌。首次描述了这些物种的磷酸盐增溶潜力。由于根癌菌在所有分离物中都表现出最高的抗旱性，因此它们可能在未来的干燥气候中在磷酸盐增溶中发挥越来越重要的作用。将可溶解磷酸盐的根瘤菌属分为伊弗氏根瘤菌和槐属根瘤菌。首次描述了这些物种的磷酸盐增溶潜力。由于根癌菌在所有分离物中都表现出最高的抗旱性，因此它们可能在未来的干燥气候中在磷酸盐增溶中发挥越来越重要的作用。将可溶解磷酸盐的根瘤菌属分为伊弗氏根瘤菌和槐属根瘤菌。首次描述了这些物种的磷酸盐增溶潜力。由于根癌菌在所有分离物中都表现出最高的抗旱性，因此它们可能在未来的干燥气候中在磷酸盐增溶中发挥越来越重要的作用。