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Background <p><i>Niallia</i> strains have been reported to exhibit strong environmental adaptability across diverse habitats; however, the discovery of novel <i>Niallia</i> species in saline-alkaline agroecosystems and their functions in enhancing plant salt tolerance remain systematically unexplored. Saline-alkaline stress is a major abiotic constraint on global food production, creating an urgent need to discover novel strains capable of improving crop salt tolerance for sustainable agriculture.</p> Results <p>Two bacterial strains, designated 03190ᵀ and 03091, were isolated from the rhizosphere of maize grown in long-term saline-alkaline soil. Both are Gram-positive, aerobic, rod-shaped strains subjected to polyphasic taxonomic analysis and genome mining for plant growth promoting and salt tolerance genes. Phenotypic, genetic and genomic data distinguished the strains from <i>Niallia</i> species with validly published names. Compared with the closest related type strain, <i>Niallia nealsonii</i> DSM 15077ᵀ, they shared 99.16% 16S rRNA gene sequence similarity, while average nucleotide identities were 84.28% and 84.30%, and digital DNA‑DNA hybridization values were 23.6% and 23.5%, all well below the thresholds for species delineation. Phylogenetic trees based on 16S rRNA and single core genes consistently showed that the two strains formed a distinct monophyletic clade. Genomic analysis revealed complete Mrp/Kdp osmotic tolerance systems, a conserved antimicrobial resistance repertoire, and additional adaptive traits, including horizontally acquired metabolic genes, CRISPR immunity, biosynthetic gene clusters (BGCs), and a diverse array of carbohydrate-active enzymes (CAZymes) underpinning niche adaptation. In pot experiments with maize seedlings, inoculation with strain 03190ᵀ increased root fresh weight and shoot dry weight by 46.84% and 39.90%, respectively, while strain 03091 increased root fresh weight and root length by 71.17% and 45.14%; both strains significantly elevated chlorophyll content. Physiologically, strain 03091 synergistically enhanced the activities of superoxide dismutase (SOD) and peroxidase (POD), whereas strain 03190ᵀ primarily restored the salt‑suppressed SOD activity.</p> Conclusions <p>Based on polyphasic taxonomic and phylogenomic data, strains 03190ᵀ and 03091 are considered as a novel species for which the name <i>Niallia yueguangensis</i> sp. nov. is proposed, with 03190ᵀ (= JCM 37594ᵀ) designated as the type strain. This study highlights the ecological features of these strains, which enhance the salt tolerance of maize seedlings and might be used as biocontrol agents and biofertilizers for sustainable agriculture in saline-alkaline soils. Further research investigations are needed to confirm the potential application of the proposed novel type strain.</p>

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Niallia yueguangensis sp. nov., a novel bacterium from maize rhizosphere in saline-alkaline soil enhancing plant salt tolerance

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年4月18日

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  • Xing Wang,
  • Fu Yang,
  • Yijun Li,
  • Qianyu Wu,
  • Daoshun Zhang,
  • Haisheng Wang,
  • Xiaoxia Zhang

摘要

Background

Niallia strains have been reported to exhibit strong environmental adaptability across diverse habitats; however, the discovery of novel Niallia species in saline-alkaline agroecosystems and their functions in enhancing plant salt tolerance remain systematically unexplored. Saline-alkaline stress is a major abiotic constraint on global food production, creating an urgent need to discover novel strains capable of improving crop salt tolerance for sustainable agriculture.

Results

Two bacterial strains, designated 03190ᵀ and 03091, were isolated from the rhizosphere of maize grown in long-term saline-alkaline soil. Both are Gram-positive, aerobic, rod-shaped strains subjected to polyphasic taxonomic analysis and genome mining for plant growth promoting and salt tolerance genes. Phenotypic, genetic and genomic data distinguished the strains from Niallia species with validly published names. Compared with the closest related type strain, Niallia nealsonii DSM 15077ᵀ, they shared 99.16% 16S rRNA gene sequence similarity, while average nucleotide identities were 84.28% and 84.30%, and digital DNA‑DNA hybridization values were 23.6% and 23.5%, all well below the thresholds for species delineation. Phylogenetic trees based on 16S rRNA and single core genes consistently showed that the two strains formed a distinct monophyletic clade. Genomic analysis revealed complete Mrp/Kdp osmotic tolerance systems, a conserved antimicrobial resistance repertoire, and additional adaptive traits, including horizontally acquired metabolic genes, CRISPR immunity, biosynthetic gene clusters (BGCs), and a diverse array of carbohydrate-active enzymes (CAZymes) underpinning niche adaptation. In pot experiments with maize seedlings, inoculation with strain 03190ᵀ increased root fresh weight and shoot dry weight by 46.84% and 39.90%, respectively, while strain 03091 increased root fresh weight and root length by 71.17% and 45.14%; both strains significantly elevated chlorophyll content. Physiologically, strain 03091 synergistically enhanced the activities of superoxide dismutase (SOD) and peroxidase (POD), whereas strain 03190ᵀ primarily restored the salt‑suppressed SOD activity.

Conclusions

Based on polyphasic taxonomic and phylogenomic data, strains 03190ᵀ and 03091 are considered as a novel species for which the name Niallia yueguangensis sp. nov. is proposed, with 03190ᵀ (= JCM 37594ᵀ) designated as the type strain. This study highlights the ecological features of these strains, which enhance the salt tolerance of maize seedlings and might be used as biocontrol agents and biofertilizers for sustainable agriculture in saline-alkaline soils. Further research investigations are needed to confirm the potential application of the proposed novel type strain.