# Leveraging Cell‐Free Supernatants of Phyllospheric Bacteria to Combat Wheat Pathogens and Boost Growth

## TL;DR

This study shows that cell-free supernatants from two types of bacteria can help protect wheat from fungal diseases and improve its growth, offering a sustainable alternative to chemical treatments.

## Contribution

The novel contribution is the evaluation of cell-free supernatants from phyllospheric bacteria as biocontrol agents and bio-stimulants for wheat.

## Key findings

- Cell-free supernatants from Serratia marcescens and Fictibacillus spp. significantly reduced disease severity in wheat.
- Serratia marcescens CFS resulted in the highest grain count and biomass in treated wheat plants.
- Metabolomic analysis identified antifungal and growth-promoting compounds in the supernatants.

## Abstract

Wheat is a major staple crop in Pakistan but faces significant threats from biotic stressors such as powdery mildew (Blumeria graminis) and stripe rust (Puccinia striiformis). These fungal diseases can drastically reduce wheat yields, leading to substantial economic losses. This study aimed to evaluate the antifungal efficacy of Cell Free Supernatants (CFSs) from
Serratia marcescens
and Fictibacillus spp. (both originally derived from phyllosphere of
Gossypium arboreum) against these fungal pathogens and assess their impact on wheat growth and yield. Wheat plants (
Triticum aestivum
, Galaxy‐2013) were treated with CFSs from both strains, alongside control groups treated with Salicylic Acid (SA), Gibberellic Acid (GA3), and water (negative control). Disease severity was assessed using leaf area and spore count assays. Plant growth parameters, including height, fresh and dry weight, grain count, and spike number, were measured. Metabolomic analysis of the CFSs was conducted using 1H NMR. CFS treatments significantly reduced disease severity, with the lowest average percentage disease (APD) observed in the
Serratia marcescens
group for stripe rust (1.86%) and in the GA3 group for powdery mildew (1.30%). Fictibacillus spp. CFS also reduced the severity of both pathogens. CFS from
Serratia marcescens
resulted in the highest grain count and biomass. NMR analysis revealed the presence of antifungal and growth‐promoting compounds in the CFSs. CFSs from
Serratia marcescens
and Fictibacillus spp. show promise as effective bio‐stimulants and biocontrol agents against fungal diseases in wheat, offering a sustainable alternative to chemical treatments. Their application could improve wheat yield and contribute to more sustainable agricultural practices.