# Whole-Genome Sequencing and Analysis Reveals Plant Growth-Promoting Properties and Biocontrol Potential of the Crotalaria retusa Endophytic Bacillus velezensis Strain G2T39

## TL;DR

A plant-friendly bacteria called Bacillus velezensis G2T39 was found to help plants grow and fight harmful fungi, making it a promising tool for sustainable agriculture.

## Contribution

The study reveals the genetic basis for the biocontrol and plant growth-promoting traits of Bacillus velezensis G2T39 through whole-genome sequencing and analysis.

## Key findings

- Bacillus velezensis G2T39 shows biocontrol activity against multiple crop pathogens like Colletotrichum gloeosporioides and Fusarium oxysporum f. sp. Vasinfectum.
- The genome of G2T39 contains genes for secondary metabolite production and plant growth promotion, including nitrogen and phosphate metabolism.
- The strain is closely related to known biocontrol strains like B. velezensis FZB42, as confirmed by phylogenetic and genomic analyses.

## Abstract

Bacillus velezensis strain G2T39 is an endophytic bacterium previously isolated from Crotalaria retusa L., with evidenced biocontrol activity against Fusarium oxysporum f. sp. Cubense and Fusarium graminearum. In this study, it was shown that this strain also exhibited biocontrol activity against Colletotrichum gloeosporioides and Fusarium oxysporum f. sp. Vasinfectum, two important crop pathogens in tropical zones. Comprehensive phylogenetic and genomic analyses were performed to further characterize this strain. The genome of B. velezensis G2T39 consists of a single circular chromosome of 4,040,830 base pairs, with an average guanine–cytosine (GC) content of 46.35%. Both whole-genome-based phylogeny and average nucleotide identity (ANI) confirmed its identity as B. velezensis, being closely related to biocontrol and plant growth promotion Gram-positive model strains such as B. velezensis FZB42. Whole-genome annotation revealed 216 carbohydrate-active enzymes and 14 gene clusters responsible for secondary metabolite production, including surfactin, macrolactin, bacillaene, fengycin, bacillibactin, bacilysin, and difficidin. Genes involved in plant defense mechanisms were also identified. Additionally, G2T39 genome harbors multiple plant growth-promoting traits, such as genes associated with nitrogen metabolism (nifU, nifS, nifB, fixB, glnK) and a putative phosphate metabolism system (phyC, pst glpQA, ugpB, ugpC). Additional genes linked to biofilm formation, zinc solubilization, stress tolerance, siderophore production and regulation, nitrate reduction, riboflavin and nicotinamide synthesis, lactate metabolism, and homeostasis of potassium and magnesium were also identified. These findings highlight the genetic basis underlying the biocontrol capacity and plant growth-promoting properties of B. velezensis G2T39 and support its potential application as a sustainable bioinoculant in agriculture.