Liu Jumei, Han Jingjing, Zhu Chunwu, Cao Weiwei, Luo Ying, Zhang Meng, Zhang Shaohua, Jia Zhongjun, Yu Ruihong, Zhao Ji, Bao Zhihua
Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau and Inner Mongolia Key Laboratory of Grassland Ecology, School of Ecology and Environment, Inner Mongolia University, Hohhot, China.
Inner Mongolia Key Laboratory of Environmental Pollution Control and Waste Resource Reuse, Inner Mongolia University, Hohhot, China.
Front Microbiol. 2021 Apr 21;12:628108. doi: 10.3389/fmicb.2021.628108. eCollection 2021.
Elevated atmospheric CO (eCO) results in plant growth and N limitation, yet how root-associated nitrogen-fixing bacterial communities respond to increasing atmospheric CO and nitrogen fertilization (eN) during the growth stages of rice is unclear. Using the gene as a molecular marker, we studied the combined effect of eCO and eN on the diazotrophic community and abundance at two growth stages in rice (tillering, TI and heading, HI). Quantitative polymerase chain reaction (qPCR) showed that eN had no obvious effect on abundance in rice roots under either ambient CO (aCO) or eCO treatment at the TI stage; in contrast, at the HI, copy numbers were increased under eCO and decreased under aCO. For rhizosphere soils, eN significantly reduced the abundance of under both aCO and eCO treatment at the HI stage. Elevated CO significantly increased the abundance in rice roots and rhizosphere soils with nitrogen fertilization, but had no obvious effect without N addition at the HI stage. There was a significant interaction [CO × N fertilization] effect on abundance in root zone at the HI stage. In addition, the copy numbers in rice roots were significantly higher at the HI stage than at the TI stage. Sequencing analysis indicated that the root-associated diazotrophic community structure tended to cluster according to the nitrogen fertilization treatment and that were the dominant diazotrophs in all root samples at the HI stage. Additionally, nitrogen fertilization significantly increased the relative abundance of () under eCO treatment, but significantly decreased the relative abundance of () under aCO treatment. Overall, the combined effect of eN and eCO stimulates root-associated diazotrophic methane-oxidizing bacteria while inhibits heterotrophic diazotrophs.
大气中二氧化碳浓度升高（eCO）会导致植物生长和氮素限制，然而在水稻生长阶段，与根系相关的固氮细菌群落如何响应不断增加的大气二氧化碳浓度和氮肥（eN）尚不清楚。我们以 基因作为分子标记，研究了eCO和eN对水稻两个生长阶段（分蘖期，TI和抽穗期，HI）固氮群落及丰度的综合影响。定量聚合酶链反应（qPCR）表明，在TI阶段，无论是在环境二氧化碳浓度（aCO）还是eCO处理下，eN对水稻根系中 的丰度均无明显影响；相反，在HI阶段，eCO处理下 的拷贝数增加，而aCO处理下则减少。对于根际土壤，在HI阶段，aCO和eCO处理下，eN均显著降低了 的丰度。在HI阶段，二氧化碳浓度升高在施肥条件下显著增加了水稻根系和根际土壤中 的丰度，但在不施氮时无明显影响。在HI阶段，根区 的丰度存在显著的[CO×氮肥]交互作用。此外，水稻根系中 的拷贝数在HI阶段显著高于TI阶段。测序分析表明，与根系相关的固氮群落结构倾向于根据氮肥处理聚类，并且在HI阶段所有根系样本中 是主要的固氮菌。此外，氮肥显著增加了eCO处理下 （ ）的相对丰度，但显著降低了aCO处理下 （ ）的相对丰度。总体而言，eN和eCO的综合作用刺激了与根系相关的固氮甲烷氧化细菌，同时抑制了异养固氮菌。
