Differential interactions between Curtobacterium flaccumfaciens pv. flaccumfaciens and common bean

Area of Science:

• Plant Pathology
• Bacteriology
• Genetics

Background:

• Bacterial wilt, caused by Curtobacterium flaccumfaciens pv. flaccumfaciens, significantly impacts common bean yield by obstructing water and nutrient transport.
• The existence of distinct physiological races within this pathogen has not been previously documented.

Purpose of the Study:

• To identify physiological races of Curtobacterium flaccumfaciens pv. flaccumfaciens.
• To evaluate the differential interactions between pathogen isolates and common bean genotypes.
• To select common bean genotypes exhibiting resistance to bacterial wilt.

Main Methods:

• Inoculation of 30 common bean genotypes with eight aggressive Curtobacterium flaccumfaciens pv. flaccumfaciens isolates under greenhouse conditions.
• Disease assessment 15 days post-inoculation.
• Partial diallel analysis to identify differential interactions and ecovalence estimation for differential genotype selection.

Main Results:

• Differential interactions between pathogen isolates and bean genotypes were confirmed, indicating the presence of physiological races.
• Isolates BRM 14939 and BRM 14942 were identified as highly aggressive, while BRM 14941 and BRM 14946 were least aggressive.
• Genotypes IPA 9, Ouro Branco, and Michelite showed higher resistance; IAC Carioca Akytã, BRS Notável, Pérola, IAC Carioca Aruã, and Coquinho were identified as differentials.

Conclusions:

• Physiological races of Curtobacterium flaccumfaciens pv. flaccumfaciens exist, necessitating tailored disease management.
• Resistant common bean genotypes were successfully identified.
• A set of differential bean genotypes was proposed for future pathogen characterization and breeding programs.