Luo Xue, Ye Xianfeng, Wang Wenhui, Chen Yang, Li Zhoukun, Wang Yanxin, Huang Yan, Ran Wei, Cao Hui, Cui Zhongli
Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Science, Nanjing Agricultural University, Nanjing, China.
School of Life Sciences, Anhui Agricultural University, Hefei, China.
Front Microbiol. 2022 Oct 13;13:1016547. doi: 10.3389/fmicb.2022.1016547. eCollection 2022.
Plant-associated nitrogen-fixing microorganisms (diazotrophs) are essential to host nutrient acquisition, productivity and health, but how host growth affects the succession characteristics of crop diazotrophic communities is still poorly understood. Here, Illumina sequencing of DNA- and RNA-derived genes was employed to investigate the dynamics of total and active diazotrophic communities across rhizosphere soil and rice roots under four fertilization regimes during three growth periods (tillering, heading and mature stages) of rice in 2015 and 2016. Our results indicated that 71.9-77.2% of the operational taxonomic units (OTUs) were both detected at the DNA and RNA levels. According to the nonmetric multidimensional scaling ordinations of Bray-Curtis distances, the variations in community composition of active rhizosphere diazotrophs were greater than those of total rhizosphere diazotrophs. The community composition (-diversity) of total and active root-associated diazotrophs was shaped predominantly by microhabitat (niche; ≥ 0.959, < 0.001), followed by growth period ( ≥ 0.15, < 0.001). The growth period had a stronger effect on endophytic diazotrophs than on rhizosphere diazotrophs. From the tillering stage to the heading stage, the -diversity indices (Chao1, Shannon and phylogenetic diversity) and network topological parameters (edge numbers, average clustering coefficient and average degree values) of total endophytic diazotrophic communities increased. The proportions of OTUs shared by the total rhizosphere and endophytic diazotrophs in rhizosphere diazotrophs gradually increased during rice growth. Moreover, total diazotrophic -diversity and network complexity decreased from rhizosphere soil to roots. Collectively, compared with total diazotrophic communities, active diazotrophic communities were better indicators of biological response to environmental changes. The host microhabitat profoundly drove the temporal dynamics of total and active root-associated diazotrophic communities, followed by the plant growth period.
与植物相关的固氮微生物（固氮菌）对于宿主养分获取、生产力和健康至关重要，但宿主生长如何影响作物固氮菌群落的演替特征仍知之甚少。在这里，利用Illumina测序技术对DNA和RNA衍生基因进行测序，以研究2015年和2016年水稻三个生长时期（分蘖期、抽穗期和成熟期）四种施肥制度下根际土壤和水稻根系中总固氮菌群落和活性固氮菌群落的动态变化。我们的结果表明，71.9%-77.2%的可操作分类单元（OTU）在DNA和RNA水平均被检测到。根据Bray-Curtis距离的非度量多维尺度排序，活性根际固氮菌群落组成的变化大于总根际固氮菌群落。总根际和活性根际相关固氮菌的群落组成（多样性）主要受微生境（生态位；≥0.959，<0.001）影响，其次是生长时期（≥0.15，<0.001）。生长时期对内生固氮菌的影响比对根际固氮菌的影响更强。从分蘖期到抽穗期，总内生固氮菌群落的多样性指数（Chao1、Shannon和系统发育多样性）和网络拓扑参数（边数、平均聚类系数和平均度值）增加。在水稻生长过程中，根际固氮菌中总根际和内生固氮菌共有的OTU比例逐渐增加。此外，从根际土壤到根系，总固氮菌多样性和网络复杂性降低。总体而言，与总固氮菌群落相比，活性固氮菌群落是对环境变化生物响应的更好指标。宿主微生境深刻驱动了总根际和活性根际相关固氮菌群落的时间动态，其次是植物生长时期。
