Enabling genome editing in tropical maize lines

Genome editing is a powerful tool to accelerate plant breeding, but its large-scale application still confronts significant challenges. Prominently among these is the recalcitrance to traditional genetic transformation protocols exhibited by many genotypes of important crop species. Despite the widespread use of a few maize genotypes amenable to genetic transformation, these are unsuitable for agronomic tests in field trials or commercial applications. This hindrance is somewhat aggravated by the fact that most of the known transformable maize lines are adapted to temperate geographies, whereas a considerable proportion of maize production happens in the tropics. To overcome the low efficiency and genotype dependency of genetic transformation, various techniques have recently been developed and are constantly being refined. Ectopic expression of morphogenic regulators is among the most promising approaches to achieve universal transformation and genome editing capabilities in maize. Here, we report the successful genome editing of agronomically relevant tropical maize lines using a morphogenic regulators-based protocol. To this end, we used a RNA-guided endonuclease based construct aiming at the knockout of the VIRESCENT YELLOW-LIKE gene, which results in an easily recognizable phenotype.