Northeastern Pacific biogeography of Labyrinthula phylogenetic diversity highlights ubiquity of L. zosterae and emergence of a novel pathogenic species
This study investigates the genetic diversity of the protist Labyrinthula in eelgrass (Zostera marina) ecosystems, an ideal model for host-pathogen dynamics. Labyrinthula zosterae (Lz), the pathogen responsible for eelgrass wasting disease, induces lesions on eelgrass leaves, causing tissue necrosis, shoot mortality, and habitat loss. We collected eelgrass samples from Alaska to Southern California and performed high-throughput sequencing targeting the 18S gene. We identified two dominant pathogenic strains: one in the Lz clade, similar to strains identified as pathogenic in the Pacific and Atlantic outbreaks, and a novel strain associated with crescent-shaped lesions.