College of Resources and Environment, Shanxi Agricultural University, Taiyuan 030031, China.
College of Resources and Environment, Shanxi Agricultural University, Taiyuan 030031, China.
Sci Total Environ. 2021 May 20;770:144742. doi: 10.1016/j.scitotenv.2020.144742. Epub 2021 Jan 23.
Rhizosphere microbiota play a pivotal role in promoting plant growth and defending against pathogens, but their responses to abiotic environmental stress remain largely elusive. Here, we investigated the influences of low-N stress on rhizosphere bacteria of six sorghum cultivars in a glasshouse experiment. The alpha diversity of bacteria (as revealed by Shannon diversity and Chao1 richness indices) was remarkably lower in rhizosphere soils than in bulk soils, and was significantly higher under low-N stress than under N addition. Principal coordinates analysis revealed that the bacterial community compositions in rhizosphere soils were clearly separated from bulk soils, and the rhizosphere soils under low-N stress or with N fertilization were clearly separated, indicating that both rhizosphere effects and N fertilization impacted the rhizosphere bacterial community. Notably, the relative abundances of beneficial bacteria such as Bacillaceae and Streptomycetaceae significantly increased in rhizosphere soils under low-N stress, which had significantly positive correlations with the sorghum N uptake. The relative abundance of Nitrosomonadaceae in rhizosphere soils was significantly lower than that in bulk soils, while the relative abundance of Rhizobiaceae showed an opposite pattern. Taken together, our results suggested that sorghum rhizosphere effects can reduce soil bacterial diversity possibly through recruiting specific bacterial species under low N stress.
根际微生物在促进植物生长和抵御病原体方面起着关键作用，但它们对非生物环境胁迫的反应在很大程度上仍不清楚。在这里，我们在温室实验中研究了低氮胁迫对 6 个高粱品种根际细菌的影响。细菌的α多样性（通过 Shannon 多样性和 Chao1 丰富度指数揭示）在根际土壤中明显低于在非根际土壤中，在低氮胁迫下显著高于氮添加下。主坐标分析显示，根际土壤中的细菌群落组成明显与非根际土壤分离，低氮胁迫或氮施肥下的根际土壤也明显分离，表明根际效应和氮施肥都影响根际细菌群落。值得注意的是，有益细菌（如芽孢杆菌科和链霉菌科）的相对丰度在低氮胁迫下的根际土壤中显著增加，与高粱氮吸收呈显著正相关。根际土壤中硝化单胞菌科的相对丰度明显低于非根际土壤，而根瘤菌科的相对丰度则呈现相反的模式。总之，我们的结果表明，高粱根际效应可以通过在低氮胁迫下招募特定的细菌物种来降低土壤细菌多样性。
