耐低氮磷回交系水稻群体中根际促生菌的筛选、鉴定及其应用探索

Isolation, identification, and application of plant growth-promoting rhizobacteria from backcross inbred rice populations with tolerance to low nitrogen and low phosphorus

摘要:

目的 从低氮磷处理的耐低氮磷水稻品种YTZ和耐低氮磷水稻回交子代品种H8的根系组织中分离并筛选出具有促生功能的水稻根际促生菌。方法 采用平板划线法分离纯化菌株；利用16S rRNA基因测序等方法进行菌种鉴定；通过解磷、固氮、产吲哚-3-乙酸(indole-3-acetic acid, IAA)等功能指标筛选促生菌株；对目标菌株进行全基因组测序分析，挖掘其功能基因，揭示其分子机制。通过盆栽试验测定根际相关土壤理化性质，探究目标菌株对水稻苗期氮、磷吸收效率的促进作用；利用16S rRNA基因扩增子测序分析其对水稻根际微生物群落结构的影响，结合菌群构建及菌群载体效果评价探索菌剂的应用潜力。结果 共筛选出7株具有解磷、固氮能力的菌株，并对其IAA产生能力进行定量分析，最终筛选出5株具代表性的菌株进行盆栽试验。其中，高地芽孢杆菌(Bacillus altitudinis) Hxx04的促生效果最为显著，使水稻植株鲜重增加47.2%，株高增加48.6%，显著提升了水稻苗期氮、磷吸收效率。根际土壤中全氮、碱解氮、全磷及有效磷含量均显著降低，表明目标菌株促进了水稻对氮磷养分的吸收。群落分析显示，接入目标菌株后根际群落呈现高丰度分布，为水稻生长提供了氮素营养支持。在以B. altitudinis Hxx04为核心菌株的两两联合接种(双菌组合)评估中“膨润土+秸秆”载体组合效果最佳。结论 菌株B. altitudinis Hxx04能高效利用氮磷并显著促进水稻生长，使水稻在鲜重和株高方面均有显著提升，同时减少了对化肥的依赖，兼具增产与环境保护效益。本研究为绿色农业提供了新的微生物资源与理论支持，有助于实现水稻氮磷高效利用与生态环境保护的协同目标。

Abstract:

Objective To isolate and characterize plant growth-promoting rhizobacteria (PGPR) from the roots of the rice variety YTZ and the backcross progeny H8 with tolerance to low nitrogen and low phosphorus, and evaluate the potential of PGPR in promoting the growth of rice seedlings.Methods Bacterial strains were isolated by plate streaking and taxonomically identified through 16S rRNA gene sequencing. Functional traits, including phosphate solubilization, nitrogen fixation, and indole-3-acetic acid (IAA) production, were assessed for strain selection. Whole-genome sequencing was performed to mine functional genes and elucidate potential molecular mechanisms of target strains. Pot experiments were conducted to evaluate strain effects on the physicochemical properties of soil and nutrient (nitrogen and phosphorus) uptake of seedlings, while 16S rRNA gene amplicon sequencing was employed to analyze rhizosphere microbial community dynamics. In addition, synthetic microbial consortia and carrier combinations were developed and assessed for application feasibility.Results Seven strains with phosphate-solubilizing and nitrogen-fixing capabilities were obtained, and their IAA production was quantitatively determined. Five representative strains were selected for pot experiments. Among them, B. altitudinis Hxx04 exhibited the strongest plant growth-promoting effect, increasing the fresh weight by 47.2% and plant height by 48.6%, while significantly enhancing nitrogen and phosphorus uptake efficiency of rice seedlings. Inoculation with Hxx04 led to marked reductions in soil total nitrogen, alkali-hydrolyzable nitrogen, total phosphorus, and available phosphorus, indicating improved nutrient uptake by rice plants. Rhizosphere community analysis revealed increased microbial abundance following inoculation, which supported the nitrogen supply for seedling growth. Furthermore, a synthetic microbial consortium centered on B. altitudinis Hxx04 performed optimally when being inoculated with the carrier combination of bentonite and straw.Conclusion B. altitudinis Hxx04 demonstrated high efficiency in nitrogen and phosphorus utilization and significantly promoted rice growth (evidenced by increased fresh weight and plant height), thereby reducing chemical fertilizer dependence. Its dual contribution to yield enhancement and environmental sustainability highlights its potential as a valuable microbial resource for green agriculture, supporting the goal of coordinating nutrient use efficiency with ecological conservation in rice production.