Exploring the endophytic microbiome of maize leaves: roles in plant growth promotion and defense against Bipolaris maydis

Abstract

Background and aims

The growing global population, expected to reach 9.7 billion, is driving an increased demand for food production. While chemical crop protection is commonly used, concerns over its environmental impact and safety have shifted focus toward developing safer and more sustainable alternatives. Biological control of Maydis leaf blight (MLB) in maize, through naturally occurring endophytic bacteria from the phyllosphere, presents an eco-friendly option. The phyllosphere, home to diverse microbial communities collectively known as the phyllomicrobiome, holds significant potential for biocontrol strategies.

Methods

The maize phyllomicrobiome was analyzed using both microbial metabarcoding and conventional microbiological techniques. Diversity analysis was conducted for both total and culturable microbiomes. Endophytic bacterial isolates were assessed for their functional potential, followed by field validation. The expression of maize candidate genes was analyzed using qPCR.

Results

Through 16S rRNA gene sequencing, ten distinct bacterial species were identified from the maize phyllosphere: Alcaligenes (2), Brevundimonas (2), Pseudomonas (3), Microbacterium (1), Proteus (1), and Stenotrophomonas (1). Over 50% of these isolates demonstrated significant inhibition of Bipolaris maydis, the causal agent of MLB, through the production of secretory or volatile metabolites. Among them, Pseudomonas aeruginosa, Brevundimonas olei, and Stenotrophomonas maltophilia suppressed MLB symptoms by more than 60% in planta. These strains also exhibited strong plant growth promotion and nutrient solubilization activity.

Conclusions

This study identifies promising endophytic bacteria, including Stenotrophomonas, Brevundimonas, and Pseudomonas, from the maize phyllosphere as potential sustainable solutions for enhancing maize health and productivity.