Galindo-Castañeda Tania, Kost Elena, Giuliano Elena, Conz Rafaela Feola, Six Johan, Hartmann Martin
Institute of Agricultural Sciences, Department of Environmental Systems Science, ETH Zurich, Zurich, Switzerland.
Ann Bot. 2025 Aug 12. doi: 10.1093/aob/mcaf185.
A major challenge in agriculture is the low nitrogen (LN) uptake efficiency of crops, which poses environmental and economic costs. Root adaptive architectural and anatomical phenotypes in synergy with root microbes could be a promising approach to improve plant N uptake. However, little is known about such synergies. Here, we aimed to characterize the spatial distribution of the root prokaryotes of maize (Zea mays) under LN in 30 L mesocosms, where root architecture and anatomy are freely expressed, searching for correlations between prokaryotic genus abundance and 10 phenotypes.
We studied the root prokaryotic community of 4-week-old plants growing in 30 L mesocosms under LN using two sandy soil mixtures. We collected root, rhizosphere, and bulk soil samples at various locations, including depths (0-20, 20-70, 70-150 cm), root classes (lateral and axial), and root types (seminal and crown). We measured plant growth response to low N availability and performed 16S rRNA gene metabarcoding on extracted DNA.
Sampling location was the third most important factor after soil mixture and compartment, explaining ∼5% of the variance in root prokaryotic diversity. Seminal roots (0-20 cm depth), shallow crown roots (0-20 cm), and deep crown roots (20-150 cm) showed well-separated root microbial communities. Lateral root branching density (LRBD) explained 10% of this variance in the rhizosphere and the root tissue. We identified prokaryotic genera specific to depth, soil-root compartment, root class, and type under LN. Moreover, architectural phenotypes LRBD and lateral root length significantly correlated with the abundance of 37 genera.
We highlight the importance of sampling location and architectural traits that may be associated with the microbial cycling of soil N. The exploration of synergies between root traits and microbes that participate in the N cycle has the potential to increase sustainability in agriculture.
农业面临的一个重大挑战是作物的低氮吸收效率，这带来了环境和经济成本。根系适应性结构和解剖表型与根际微生物协同作用可能是提高植物氮吸收的一种有前景的方法。然而，对于这种协同作用知之甚少。在这里，我们旨在表征在30升中型生态箱中低氮条件下玉米（Zea mays）根际原核生物的空间分布，在该生态箱中根系结构和解剖结构可以自由表达，寻找原核生物属丰度与10种表型之间的相关性。
我们使用两种沙质土壤混合物研究了在30升中型生态箱中低氮条件下生长的4周龄植物的根际原核生物群落。我们在不同位置采集根、根际和土壤样本，包括深度（0 - 20、20 - 70、70 - 150厘米）、根类（侧根和轴根）以及根型（胚根和冠根）。我们测量了植物对低氮有效性的生长响应，并对提取的DNA进行16S rRNA基因代谢组测序。
采样位置是仅次于土壤混合物和区室的第三重要因素，解释了根际原核生物多样性约5%的变异。胚根（0 - 20厘米深度）、浅层冠根（0 - 20厘米）和深层冠根（20 - 150厘米）显示出明显不同的根际微生物群落。侧根分支密度（LRBD）解释了根际和根组织中这种变异的10%。我们确定了低氮条件下特定于深度、土壤 - 根区室、根类和根型的原核生物属。此外，结构表型LRBD和侧根长度与37个属的丰度显著相关。
我们强调了采样位置和可能与土壤氮微生物循环相关的结构特征的重要性。探索参与氮循环的根性状与微生物之间的协同作用有可能提高农业的可持续性。
