Culturable endophytic bacterial communities associated with field-grown soybean

Area of Science:

• Microbiology
• Plant Science
• Genetics

Background:

• Endophytic bacteria reside within plant tissues, influencing host physiology.
• Understanding these microbial communities is crucial for sustainable agriculture.
• Soybean (Glycine max) is a vital crop, and its associated microbiome can impact yield and health.

Purpose of the Study:

• To assess and compare the culturable endophytic bacterial populations in transgenic and nontransgenic soybean.
• To characterize these bacteria phenotypically and genotypically for plant growth-promoting traits.
• To investigate potential differences in bacterial communities related to soybean genotype and tissue type.

Main Methods:

• Isolation of endophytic bacteria from roots, stems, and leaves of transgenic (glyphosate-resistant) and nontransgenic soybean cultivars.
• Phenotypic characterization for plant growth-promoting activities (e.g., IAA production, phosphate solubilization).
• Genotypic identification using partial 16S rRNA gene sequencing.

Main Results:

• Significant differences in bacterial densities were observed between soybean genotypes and tissue types.
• Roots and glyphosate-resistant (GR) soybean generally showed higher bacterial numbers.
• Fifty-four strains were identified, primarily as Enterobacter ludwigii and Variovorax paradoxus.
• 44.4% of isolates produced indoleacetic acid (IAA) or solubilized phosphates; 9.2% (all from GR soybean) exhibited both traits.

Conclusions:

• The composition of culturable endophytic bacterial communities differs between transgenic and nontransgenic soybean.
• Bacterial abundance was generally higher in transgenic soybean cultivars.
• Bacterial endophytes associated with GR and nontransgenic soybean were distinct, with some showing plant growth-promoting potential.