Rice Root Exudate Modulates Functional Traits of Plant-Growth-Promoting Bacteria: A Step Towards Rhizosphere...

Area of Science:

• Agricultural Science
• Microbiology
• Plant Science

Background:

• Rhizosphere engineering optimizes plant-microbe interactions for crop productivity and soil health.
• Root exudates are crucial for recruiting and activating plant growth-promoting rhizobacteria (PGPR).

Purpose of the Study:

• To investigate the impact of rice root exudates from different cultivars and growth stages on PGPR functional traits.
• To identify key metabolites and bacterial traits involved in successful rhizosphere colonization.

Main Methods:

• Assessed growth, chemotaxis, biofilm formation, and cell wall-degrading enzyme activity of five PGPR strains exposed to root exudates from three rice cultivars.
• Analyzed root exudate composition using gas chromatography-mass spectrometry.
• Utilized principal component and correlation analyses to link PGPR traits with rhizosphere competence.

Main Results:

• Significant strain- and cultivar-specific modulation of PGPR functional traits was observed.
• Specific PGPR strains (NE14, FD48) showed enhanced traits in response to certain rice cultivar exudates.
• Identified key root exudate metabolites (e.g., hexadecanoic acid, cinnamic acid derivatives) influencing PGPR behavior.
• Cell wall-degrading enzymes and chemotaxis were key factors in PGPR strain variability and rhizosphere competence.

Conclusions:

• Root exudate composition and developmental stage critically influence PGPR colonization and functionality.
• Functional trait-based screening is essential for selecting PGPR adapted to specific rhizosphere environments.
• This study provides a framework for PGPR-mediated rhizosphere engineering to improve agricultural sustainability.