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Key message <p><i>Priestia megaterium</i> SI1-IITJ, root endophyte of Thar Desert plants, mitigates fluoride stress tolerance of <i>Arabidopsis thaliana</i> through induction of salt tolerance genes and suppression of transporters and ROS production.</p> Abstract <p>We isolated a sodium fluoride (NaF)-resistant bacterium, <i>Priestia megaterium</i> SI1-IITJ, from the internal root tissues of several Thar Desert plants, <i>Aerva javanica</i>, <i>Cyperus conglomeratus</i>, <i>Senna tora</i>, and <i>Tephrosia purpurea</i>, tolerating up to 100 mM NaF. The root endophytic behavior of the isolate was confirmed by scanning electron microscopy. SI1-IITJ possesses plant growth-promoting properties, including auxin production (19.8&#xa0;µg mL<sup>− 1</sup>), phosphate solubilization (index 3.64), aminocyclopropane-1-carboxylic acid (ACC) deaminase (0.54 mmol α-ketobutyrate mL<sup>− 1</sup>), and nitrate reductase (0.65 µmol mL<sup>− 1</sup> nitrite) activities, revealed by biochemical tests and whole genome sequencing. SI1-IITJ extrudes fluoride ions (F<sup>−</sup>) from the cell, possibly through an F<sup>−</sup> efflux transporter, <i>CrcB</i>, identified in its genome. Significant growth improvements were observed in <i>Arabidopsis thaliana</i> under F<sup>−</sup> stress in hydroponics and soil culture upon coculture with SI1-IITJ, which improved the chlorophyll content by 1.6%, total nitrogen by 30.4%, and reduced reactive oxygen species by 48.9% and F<sup>−</sup> content by 63.9% in plant tissues. A differential gene expression analysis of <i>A. thaliana</i> by transcriptome sequencing indicated an unperturbed F<sup>−</sup> exporter, <i>AtFEX1</i>, but up-regulation of 55 genes regulating root meristem growth, cell wall modification, chlorophyll biosynthesis, Fe homeostasis, and high salt- and abiotic stress-responsive genes. On the other hand, 103 genes were down-regulated, suppressing systemic acquired resistance, plant defense, and H<sub>2</sub>O<sub>2</sub> production. In conclusion, our results provide genomic insights into the mechanisms of F<sup>−</sup> toxicity alleviation and growth enhancement by a desert plant growth-promoting rhizobacterium (PGPR), highlighting <i>Priestia megaterium</i> SI1-IITJ as a potential biofertilizer for mitigating F<sup>−</sup> stress in plants.</p>

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A Desert endophyte, Priestia Megaterium SI1-IITJ, Improves Fluoride Stress Tolerance by Reducing Fluoride Content of Plant Tissues and Perturbing Salt Tolerance and Defense Genes of Arabidopsis Thaliana

  • 期刊论文

  • 发表日期：

    2025年12月11日

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  • Devanshu Verma,
  • Pinki Sharma,
  • Rishabh Kumar,
  • Neelam Jangir,
  • Vijesh Prajapat,
  • Debankona Marik,
  • Rabisankar Mandi,
  • Trisikhi Raychoudhury,
  • Nar Singh Chauhan,
  • Ayan Sadhukhan

摘要

Key message

Priestia megaterium SI1-IITJ, root endophyte of Thar Desert plants, mitigates fluoride stress tolerance of Arabidopsis thaliana through induction of salt tolerance genes and suppression of transporters and ROS production.

Abstract

We isolated a sodium fluoride (NaF)-resistant bacterium, Priestia megaterium SI1-IITJ, from the internal root tissues of several Thar Desert plants, Aerva javanica, Cyperus conglomeratus, Senna tora, and Tephrosia purpurea, tolerating up to 100 mM NaF. The root endophytic behavior of the isolate was confirmed by scanning electron microscopy. SI1-IITJ possesses plant growth-promoting properties, including auxin production (19.8 µg mL− 1), phosphate solubilization (index 3.64), aminocyclopropane-1-carboxylic acid (ACC) deaminase (0.54 mmol α-ketobutyrate mL− 1), and nitrate reductase (0.65 µmol mL− 1 nitrite) activities, revealed by biochemical tests and whole genome sequencing. SI1-IITJ extrudes fluoride ions (F−) from the cell, possibly through an F− efflux transporter, CrcB, identified in its genome. Significant growth improvements were observed in Arabidopsis thaliana under F− stress in hydroponics and soil culture upon coculture with SI1-IITJ, which improved the chlorophyll content by 1.6%, total nitrogen by 30.4%, and reduced reactive oxygen species by 48.9% and F− content by 63.9% in plant tissues. A differential gene expression analysis of A. thaliana by transcriptome sequencing indicated an unperturbed F− exporter, AtFEX1, but up-regulation of 55 genes regulating root meristem growth, cell wall modification, chlorophyll biosynthesis, Fe homeostasis, and high salt- and abiotic stress-responsive genes. On the other hand, 103 genes were down-regulated, suppressing systemic acquired resistance, plant defense, and H2O2 production. In conclusion, our results provide genomic insights into the mechanisms of F− toxicity alleviation and growth enhancement by a desert plant growth-promoting rhizobacterium (PGPR), highlighting Priestia megaterium SI1-IITJ as a potential biofertilizer for mitigating F− stress in plants.