贝莱斯芽孢杆菌FH-1通过调控特定时空的土壤微生物组促进水稻苗生长

Bacillus velezensis FH-1 promotes rice seedlings growth by regulating specific spatiotemporal soil microbiome

摘要:

【背景】以植物根际促生菌(plant growth-promoting rhizobacteria,PGPR)为核心的微生物肥料是实现农业可持续发展的重要途径。【目的】以前期获得的一株可显著促进水稻生长的贝莱斯芽孢杆菌(Bacillus velezensis) FH-1为研究对象，运用盆栽试验和高通量测序技术，在时空尺度上系统研究了其在复杂土壤系统中的演变规律及其促进水稻生长的微生物生态学机制。【方法】将贝莱斯芽孢杆菌FH-1接种水稻盆栽，在时间和空间尺度分别采取水稻和根际土壤样品，利用直尺和天平测定水稻的株高和植株干重。提取根际土壤DNA后，利用16S rRNA基因扩增子测序解析水稻根际土壤的微生物群落组成，进一步使用Spearman相关统计分析研究水稻-微生物之间的相关性。【结果】接种后第0天，处理组(F)与对照组(CK)间水稻无显著差异。随着时间推移，F组对水稻的促生效果越来越明显。接种后第20天F组中水稻株高和干重分别比CK组高6.02%和12.52%(P<0.05)。前期(接种后5–10 d)贝莱斯芽孢杆菌FH-1在地下0–3 cm土壤中的定殖丰度高于地下3–6 cm 1.19%–2.64%，通过富集地下0–3 cm土壤中的Kineosporiaceae、Chitinophagales等物种和延胡索酸呼吸(fumarate respiration)等功能，以及地下3–6 cm土壤中的Bacillaceae、Phycisphaerae等物种和nitrate ammonification等功能促进水稻生长。后期(接种后15–20 d)贝莱斯芽孢杆菌FH-1在地下0–3 cm土壤中的定殖丰度高于地下3–6 cm 134%–139%，通过富集地下0–3 cm土壤中的Bacillus、Ilumatobacteraceae等物种和xylanolysis功能，及地下3–6 cm土壤中的Acidimicrobiia、Mycobacterium等物种和respiration of sulfur compounds功能促进水稻苗早期生长。【结论】在土壤生态系统中，贝莱斯芽孢杆菌FH-1通过调控特定时空位点的微生物群落结构和功能促进水稻苗的早期生长。

Abstract:

[Background] Microbial fertilizers prepared with plant growth-promoting rhizobacteria (PGPR) are an important way to achieve sustainable agricultural development. [Objective] To systematically study the distribution of Bacillus velezensis FH-1 capable of promoting rice growth in complex soil systems and the mechanism of the strain in promoting rice growth on a spatial-temporal scale. [Methods] The rice seedlings were inoculated with B. velezensis FH-1, and rice seedling and rhizosphere soil samples in different layers were collected at different time points. The plant height and dry weight of rice seedlings were measured by a ruler and a balance, respectively. After DNA was extracted from the rhizosphere soil, 16S rRNA gene amplicon sequencing was performed to analyze the microbial community composition. Spearman correlation analysis was performed to study the correlations between rice and microorganisms. [Results] On day 0 after inoculation, there was no significant difference between the B. velezensis FH-1 (F) group and the control group (CK). The rice growth-promoting effect of group F became increasingly obvious over time. On day 20 after inoculation, the plant height and dry weight of rice seedlings in group F were 6.02% and 12.52% higher than those in group CK, respectively (P<0.05). During days 5–10 after inoculation, the colonization abundance of B. velezensis FH-1 in the 0–3 cm underground soil layer was 1.19%–2.64% higher than that in the 3–6 cm underground soil layer. During this period, B. velezensis FH-1 promoted rice growth by enriching Kineosporiaceae and Chitinophagales and promoting fumarate respiration in the 0–3 cm underground soil layer and enriching Bacillaceae and Phycisphaerae and enhancing nitrate ammonification in the 3–6 cm underground soil layer. During days 15–20 after inoculation, the colonization abundance of B. velezensis FH-1 in the 0–3 cm underground soil layer was 134%–139% higher than that in the 3–6 cm underground soil layer. During this period, B. velezensis FH-1 promoted rice growth by enriching Bacillus and Ilumatobacteraceae and promoting xylanolysis in the 0–3 cm underground soil layer and enriching Acidimicrobiia and Mycobacterium and boosting respiration of sulfur compounds in the 3–6 cm underground soil layer. [Conclusion] In the soil ecosystem, B. velezensis FH-1 promotes the early growth of rice seedlings by regulating the structure and function of the microbial community in the soil on a spatial-temporal scale.