College of Resources and Environment, Northeast Agricultural University, Harbin, China.
College of Resources and Environment, Northeast Agricultural University, Harbin, China.
Sci Total Environ. 2021 Apr 15;765:142738. doi: 10.1016/j.scitotenv.2020.142738. Epub 2020 Oct 8.
Increasing salinity and sodicity have been recognized as threats to soil fertility and crop yield worldwide. In recent years, salt-affected soils have received great attentions due to the shortage of arable land. This study therefore aims to characterize soil bacterial community, assembly process and co-occurrence network along natural saline-sodic gradients across Songnen Plain, Northeast China. As revealed by Miseq sequencing, 8482 bacterial OTUs were annotated at 97% identity across 120 soil samples. Our results indicated that soil salinity-sodicity not only significantly decreased bacterial richness and but also impacted bacterial community composition. The dominant bacterial phyla included Proteobacteria (28.89%), Actinobacteria (19.96%) and Gemmatimonadetes (16.71%). By applying threshold indicator species analysis (TITAN), OTUs from Gemmatimonadetes were found to be the taxa with the most prevalent and strongest preference for high salinity-sodicity. Null model analysis revealed that the majority (76.4%) of βNTI values were below -2 or above 2, indicating deterministic process was dominant across all samples. Notably, deterministic process contributed to a greater extent in higher saline-sodic soils. The bacterial co-occurrence network was more complex in slightly saline-sodic soils than in moderately and extremely saline-sodic soils, reflected by more nodes, more hubs and stronger connections, which was mainly driven by soil pH. These results provide strong evidence that salinity-sodicity was a key determinant in shaping soil bacterial community, assembly process and co-occurrence network pattern.
在全球范围内，盐分和碱度增加已被认为是土壤肥力和作物产量的威胁。近年来，由于耕地短缺，受盐影响的土壤受到了极大的关注。因此，本研究旨在描述中国东北松嫩平原沿自然盐-碱梯度的土壤细菌群落特征、组装过程和共生网络。通过 Miseq 测序，在 120 个土壤样本中，以 97%的同一性注释了 8482 个细菌 OTUs。我们的结果表明，土壤盐分-碱度不仅显著降低了细菌丰富度，而且还影响了细菌群落组成。优势细菌门包括变形菌门（28.89%）、放线菌门（19.96%）和芽单胞菌门（16.71%）。通过应用阈值指示物种分析（TITAN），发现芽单胞菌门的 OTUs 是对高盐-碱度最普遍和偏好最强的类群。零模型分析表明，大多数（76.4%）βNTI 值低于-2 或高于 2，表明在所有样本中，确定性过程占主导地位。值得注意的是，在较高盐-碱土壤中，确定性过程的贡献更大。与中度和极度盐-碱土壤相比，在轻度盐-碱土壤中，细菌共生网络更复杂，表现为节点更多、枢纽更多、连接更强，这主要是由土壤 pH 值驱动的。这些结果有力地证明了盐分-碱度是塑造土壤细菌群落、组装过程和共生网络模式的关键决定因素。
