# Exogenous K+ enhances the desiccation tolerance and adhesion of Pseudomonas protegens SN15-2

## TL;DR

Adding potassium improves the survival and adhesion of a beneficial soil bacterium under drying stress, helping it better protect plants.

## Contribution

Exogenous K+ and Gmd overexpression are novel strategies to enhance P. protegens desiccation tolerance and biocontrol efficacy.

## Key findings

- Exogenous K+ significantly improves desiccation tolerance in P. protegens.
- K+ enhances adhesion and promotes expression of stress-related genes like Gmd.
- Overexpression of Gmd increases viability in microcapsules under desiccation stress.

## Abstract

Pseudomonas protegens is an important plant growth-promoting rhizobacterium capable of both suppressing phytopathogens and enhancing plant growth. The ability of P. protegens to withstand desiccation stress is essential for its successful application in biocontrol.

This study investigated the effects of potassium (K+) on the desiccation tolerance and adhesion ability of P. protegens through potassium supplementation during cultivation. In addition, transcriptome sequencing and gene overexpression analysis were used to investigate the mechanism by which K+ influences desiccation tolerance in P. protegens.

The addition of exogenous K+ was found to significantly enhance the survival of P. protegens under desiccation stress. Transcriptome analysis demonstrated that K+ induced the expression of multiple genes associated with nucleotide sugar biosynthesis and signal transduction, which are closely involved in bacterial stress tolerance. Additionally, K+ was observed to enhance the adhesion capability of P. protegens, thereby contributing to its successful colonization. Further experiments revealed that the GDP-mannose 4,6-dehydratase Gmd, whose expression is upregulated by K+, plays a pivotal role in the desiccation tolerance of P. protegens. The supplementation of K+ and the overexpression of Gmd were both found to markedly enhance the viability of P. protegens in microcapsule formulations under desiccation stress.

In summary, this study provides straightforward and effective protective strategies to improve the desiccation tolerance and biocontrol efficacy of P. protegens, which is of great significance for advancing its formulation and application.