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Background and Aims <p>Phosphorus (P) deficiency is a major environmental constraint that limits crop growth. The plant microbiome plays a beneficial role in improving crop tolerance to P-deficiency. This study characterized bacterial communities associated with two foxtail millet (<i>Setaria italica</i> L.) genotypes differing in P-deficiency tolerance, aiming to elucidate root-microbe synergistic adaptation to P stress.</p> Methods <p>We used 16S rRNA sequencing to analyze α-diversity of rhizosphere and root endophytic bacteria under P-deficient conditions, and constructed co-occurrence networks to identify key functional taxa. Through microbial transplantation experiments and screening of plant growth-promoting rhizobacteria (PGPR) strains, we validated the growth-enhancing effects of microbiomes induced under P-deficient conditions.</p> Results <p>The P-tolerant foxtail millet genotype L30 exhibited enhanced adaptation to P- deficient conditions by increasing root biomass and root acid phosphatase activity. Under P deficiency, L30 and the P-sensitive genotype C33 showed higher α-diversity in their rhizosphere and root bacterial communities. Furthermore, the rhizosphere of L30 was enriched with Proteobacteria, Bacteroidota and Firmicutes, and maintained a higher degree of connectivity in the rhizobacterial co-occurrence network. The rhizobacterial community from L30 also demonstrated stronger plant growth-promoting effects. To further validate these effects, the bacterial strains isolated from the L30 rhizosphere were inoculated into P-deficient C33 seedlings in a pot experiment. Twelve strains were identified as potential PGPR, significantly increasing the plant height and shoot dry weight of C33 by 90.2% and 41.0%, respectively. Notably, four strains (SiRh2, SiRh21, SiRh26 and SiRh36) demonstrated robust capacities in inorganic phosphate solubilization, accompanied by a decrease in the medium pH.</p> Conclusion <p>This study demonstrated that foxtail millet genotypes profoundly reshaped the bacterial community structure under P-deficient conditions. The rhizosphere microbiome associated with the P-tolerant genotype enhanced the P deficiency tolerance of the P-sensitive genotype. These findings significantly enhance our understanding of the complex plant–microbe feedback mechanisms under P-deficient conditions.</p>

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Reshaping the root-associated bacterial community for enhanced phosphorus deficiency tolerance in foxtail millet

  • 期刊论文

  • 发表日期：

    2025年10月29日

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  • Xiongwei Zhao,
  • Mengqing Li,
  • Yixuan Liang,
  • Jie Zhang,
  • Jian Cui,
  • Chuang Ma,
  • Yuanhuai Han,
  • Yiwei Jiang,
  • Yanhua Cao,
  • Guofang Xing

摘要

Background and Aims

Phosphorus (P) deficiency is a major environmental constraint that limits crop growth. The plant microbiome plays a beneficial role in improving crop tolerance to P-deficiency. This study characterized bacterial communities associated with two foxtail millet (Setaria italica L.) genotypes differing in P-deficiency tolerance, aiming to elucidate root-microbe synergistic adaptation to P stress.

Methods

We used 16S rRNA sequencing to analyze α-diversity of rhizosphere and root endophytic bacteria under P-deficient conditions, and constructed co-occurrence networks to identify key functional taxa. Through microbial transplantation experiments and screening of plant growth-promoting rhizobacteria (PGPR) strains, we validated the growth-enhancing effects of microbiomes induced under P-deficient conditions.

Results

The P-tolerant foxtail millet genotype L30 exhibited enhanced adaptation to P- deficient conditions by increasing root biomass and root acid phosphatase activity. Under P deficiency, L30 and the P-sensitive genotype C33 showed higher α-diversity in their rhizosphere and root bacterial communities. Furthermore, the rhizosphere of L30 was enriched with Proteobacteria, Bacteroidota and Firmicutes, and maintained a higher degree of connectivity in the rhizobacterial co-occurrence network. The rhizobacterial community from L30 also demonstrated stronger plant growth-promoting effects. To further validate these effects, the bacterial strains isolated from the L30 rhizosphere were inoculated into P-deficient C33 seedlings in a pot experiment. Twelve strains were identified as potential PGPR, significantly increasing the plant height and shoot dry weight of C33 by 90.2% and 41.0%, respectively. Notably, four strains (SiRh2, SiRh21, SiRh26 and SiRh36) demonstrated robust capacities in inorganic phosphate solubilization, accompanied by a decrease in the medium pH.

Conclusion

This study demonstrated that foxtail millet genotypes profoundly reshaped the bacterial community structure under P-deficient conditions. The rhizosphere microbiome associated with the P-tolerant genotype enhanced the P deficiency tolerance of the P-sensitive genotype. These findings significantly enhance our understanding of the complex plant–microbe feedback mechanisms under P-deficient conditions.