Population Structure and Pathogenic Diversity of Colletotrichum lindemuthianum in Common Bean Growing Regions

Abstract

Population structure and pathogenic diversity of Colletotrichum lindemuthianum in common bean growing regions were investigated to understand variability in virulence, host specificity, and regional distribution of anthracnose pathogen populations. Field surveys were conducted across major bean-producing areas, and infected plant samples exhibiting typical anthracnose symptoms such as dark sunken lesions on pods, stem cankers, and leaf necrosis were collected. Fungal isolates were obtained and characterized based on cultural morphology, growth rate, and sporulation patterns on standard media. Pathogenic variability was assessed through inoculation on differential bean cultivars to determine race composition and virulence profiles. Results revealed high genetic and pathogenic diversity among C. lindemuthianum populations, indicating the presence of multiple physiological races within and across regions. Significant differences in virulence were observed among isolates, with certain populations showing broad virulence spectra capable of infecting multiple host differentials. Molecular analysis supported the observed variability, revealing distinct genetic groupings correlated with geographic origin and host interaction patterns. Population structure analysis suggested limited gene flow between regions, contributing to localized differentiation and emergence of region-specific pathogen profiles. The study highlights the dynamic nature of C. lindemuthianum populations and their rapid adaptation to host resistance genes in common bean. These findings emphasize the need for continuous monitoring of pathogen diversity and the deployment of durable resistance strategies in bean breeding programs.