First Reported Sexual Recombination Between Isolates from Barley and Barley Grass.

Barley grass (), which often occurs in proximity to commercial barley () cultivars, is an alternative host to , an economically important pathogen causing net blotch in barley. This study is the first to report the sexual recombination of isolates collected from barley with those collected from barley grass. The sexual recombination between isolates from barley and barley grass was confirmed using a neighbor-net network and haploblock plots based on whole-genome sequencing of seven progeny isolates. Pathogenicity assays revealed that isolates from barley grass were not host specific and could infect both barley and barley grass, and the progeny isolates were virulent on commercially grown barley cultivars. Our results contradict previous population and pathogenicity studies of isolates obtained from barley and barley grass that have reported that the two populations are genetically distinct and host specific, suggesting that isolates collected from barley or barley grass could be two different entities. Despite the genetic divergence of isolates from barley and barley grass revealed through our phylogenomic analysis, there seems to be no complete host or reproductive separation between these populations. Therefore, there is a potential for generation of novel pathotypes through sexual recombination between s isolates associated with barley and barley grass, with a risk of increased impacts on commercial barley cultivars that do not carry resistance to these pathotypes.