Comparative genomics and metabolomics reveal phytohormone production, nutrient acquisition, and osmotic stress tolerance in Azotobacter chroococcum W5

TL;DR

This study explores how Azotobacter chroococcum W5, a plant growth-promoting bacterium, helps crops by producing hormones, acquiring nutrients, and tolerating stress.

Contribution

The study combines comparative genomics and metabolomics to reveal novel stress tolerance and growth-promoting traits in Azotobacter chroococcum W5.

Findings

A. chroococcum W5 produces phytohormones and solubilizes phosphate, aiding plant growth.

The strain shows osmotic stress tolerance through elevated osmoprotectants like proline and glycerol.

Wheat seed inoculation with W5 improves germination and seedling vigor.

Abstract

Concerns about ecological degradation and reduced biodiversity have intensified the search for sustainable solutions in agriculture. The use of plant growth-promoting bacteria (PGPB) offers a promising alternative to enhance soil quality and crop yield while reducing the consumption of chemical fertilizers.

Here, we characterize the plant growth-promoting potential of Azotobacter chroococcum W5 through comparative genomics, in vitro experiments, and metabolomic analyses.

Comparative genomic analysis revealed plant growth-promoting traits, including phytohormone biosynthesis, nutrient acquisition, stress adaptation, and colonization in the A. chroococcum W5 strain. Experimental assays confirmed the production of auxin, gibberellic acid, phosphate solubilization, moderate nitrogen fixation, and growth on ACC. Wheat seed inoculation significantly enhanced germination metrics, seedling vigor, and altered carbohydrate metabolism in the seed endosperm. Under salt and osmotic stress, A. chroococcum W5 metabolomic profiling revealed adaptive responses, including elevated levels of osmoprotectants (proline, glycerol) and oxidative stress markers such as 2-hydroxyglutarate, while putrescine and glycine decreased.

Our results show that the A. chroococcum W5 strain has great potential for the development of novel formulations. More importantly, our results highlight the potential of using plant growth-promoting microorganisms for innovative, sustainable solutions in agriculture.

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