Articles of Significant Interest in This Issue.

Abstract

The reduced genetic diversity of monoculture agricultural crops has been associated with adaptation of plant pathogens to local environments. This is of concern on a global scale for emerging plant pathogens such as the bacterium Xylella fastidiosa. Castillo et al. (e02095-20) show that following its establishment in the U.S., grapevine-infecting strains of X. fastidiosa split into populations on the East and West Coasts. Subsequently, population diversification occurred via nucleotide changes in the core genome sequences and gene gain/loss. This finding shows that X. fastidiosa populations can quickly become differentiated, which may lead to local pathogen specialization in newly introduced landscapes.