Interplay between wheat cultivars, biocontrol pseudomonads, and soil

Area of Science:

• Plant-microbe interactions
• Agricultural microbiology
• Plant breeding

Background:

• Root-colonizing pseudomonads offer plant benefits, but wheat genotype interactions are poorly understood.
• Cultivar-specific accumulation of beneficial bacteria in the wheat rhizosphere and influencing factors require investigation.
• Optimizing pseudomonad-wheat interactions can enhance plant growth and reduce reliance on chemical inputs.

Purpose of the Study:

• To characterize three Swiss winter wheat cultivars (Arina, Zinal, Cimetta) for their capacity to accumulate plant-beneficial pseudomonads.
• To assess cultivar-specific selection of 2,4-diacetylphloroglucinol (DAPG)-producing Pseudomonas genotypes in different soils.
• To evaluate wheat cultivar responses to Pseudomonas inoculants for plant growth promotion and pathogen protection.

Main Methods:

• Cultivar screening for rhizosphere pseudomonad accumulation.
• Denaturing gradient gel electrophoresis (DGGE) of the phlD gene to analyze Pseudomonas genotype diversity.
• Plant growth assays with Pseudomonas inoculants in the presence and absence of Pythium ultimum.

Main Results:

• Significant cultivar-specific differences in pseudomonad accumulation were observed, strongly influenced by soil type.
• Soil type and wheat cultivar interacted to shape the diversity and abundance of specific Pseudomonas genotypes (phlD), with some genotypes accumulating in a cultivar-specific manner in one soil.
• While Arina showed superior protection against Pythium ultimum with Pseudomonas fluorescens CHA0, it benefited least from growth promotion by bacterial inoculants without the pathogen.

Conclusions:

• Wheat cultivar choice and soil type are critical factors in managing beneficial rhizosphere pseudomonads.
• Cultivar-specific selection of Pseudomonas genotypes, particularly DAPG producers, can be soil-dependent.
• Breeding wheat for enhanced beneficial microbial interactions, considering cultivar-soil type compatibility, offers a novel strategy for low-input and organic farming systems.