Guard Cell Metrics in Common and Japanese Hops from Wild, Feral, and Cultivated Backgrounds

Japanese hops are a closely related annual relative of the perennial crop species common hops, as such they are a potential genetic resource for accelerating hop breeding and cultivar development. Ploidy manipulation is an important tool in common hop breeding. In other crop systems, epidermal peels measuring guard cell traits-length, width, and plastid number-provide a rapid and low-cost method for screening ploidy levels. Guard cell length in Japanese hop exhibited intraindividual variability but appeared potentially less environmentally sensitive than plastid-based metrics in Japanese hop and trended higher in the tested triploid cultivar.