# Bacterial consortia enhance nutrient uptakes and molecular response in tomato seedlings under alkaline soil stress: a comparative study

## TL;DR

This study shows that using a mix of two bacteria can help tomato plants grow better in alkaline soils by improving nutrient uptake and stress resistance.

## Contribution

The novelty lies in demonstrating the effectiveness of a bacterial consortium in enhancing plant growth and molecular responses under alkaline soil stress.

## Key findings

- Bacterial consortia improved germination, root and shoot development, and seedling vigor in alkaline soils.
- The consortium increased protein, proline, antioxidant activity, and flavonoid content in treated plants.
- Nutrient-regulating genes were activated, enhancing root metabolism and stress resilience in plants.

## Abstract

Nutrient deficiencies in alkaline soils (pH 7.9–8.5) frequently limit plant growth due to insufficient nutrient availability and uptake. This study investigated the effects of two bacterial strains, VITK-1 (Pseudomonas sp.) and VITK-3 (Burkholderia sp.), on nutrient absorption, growth, and gene expression in tomato (Solanum lycopersicum) seedlings grown in alkaline soil. Bacterial treatments were applied individually and as a consortium, and their ability to promote plant growth and nutrient solubility was evaluated. In vitro studies demonstrated the strains’ ability to solubilize essential nutrients, generate extracellular enzymes, and exhibit a variety of Plant Growth-Promoting Rhizobacteria (PGPR) characteristics, with strong antagonistic activity against Fusarium oxysporum f.sp. lycopersici and Ralstonia solanacearum (35.7%–76.5%). In vivo investigations revealed notable improvements in germination (73.3%), root and shoot development, and overall seedling vigor when compared to untreated controls. The bacterial consortium significantly improved protein (54.5%) and proline (69.5%) levels, antioxidant activity (50.7%), phenolic (60.9%), and flavonoid content (52.5%), and decreased carbohydrate accumulation. Furthermore, treated plants exhibited activation of nutrient-regulating genes (NRT2, PR-1, and AMT-1) associated with better root metabolism (improved 1.58–1.70 mg) and resilience to stress (GR-1 and DREB3). These results show the potential of PGPR inoculants, particularly consortia, as a promising strategy for improving nutrient uptake, biochemical characteristics, and stress tolerance in crops grown in alkaline soils.

Illustration of a plant showing the effects of bio-priming with PGPR (plant growth-promoting rhizobacteria) on plant growth and nutrient uptake. The diagram displays increased growth attributes, nutrient content, antioxidant activity, root elongation, protein, and carbohydrate levels. Roots absorb multiple nutrients and interact with PGPR consortium, improving soil pH and nutrient availability.