Clonal Expansion From Standing Genetic Variation Underpins the Evolution of an Emerging Plant Pathogen in Australia

This study investigates the genetic and phenotypic diversity of the plant pathogen Curtobacterium flaccumfaciens pv. flaccumfaciens, responsible for tan spot in mungbean in Australia. By analyzing 119 isolates collected from 1986 to 2019, researchers found that the pathogen's evolution is driven by clonal expansion from existing genetic variation rather than new genotypes. The study highlights the importance of understanding pathogen diversity and aggressiveness to guide breeding programs for effective disease resistance. It emphasizes the need for robust screening protocols and the selection of aggressive, locally representative isolates to ensure accurate resistance assessment in crops. This research is crucial for developing informed breeding strategies to manage the spread and impact of tan spot, a significant pathogen with a broad host range.