Genome engineering holds great promise for producing new plant varieties better able to feed the increasing global population. In many species, this approach requires selectively coaxing small clumps of cells carrying DNA sequences of interest to regenerate into whole plants with well-organized shoots and roots. Although regeneration is readily achieved and allows for successful genome engineering in some plant species, regeneration is still too low-throughput or prohibitively difficult in many crops. A critical challenge then is defining and overcoming the barriers that frustrate regeneration in these species. The proposed research will address this problem by investigating why whole plant regeneration is so hard to achieve in sunflower, a globally significant oil and confectionary seed crop. Specifically, the responses of cultivated sunflower cells and tissues to various experimental regeneration conditions will be characterized, and these observations will be compared to the responses of more easily regenerated relatives in the sunflower family. These results will then be leveraged to design experimental interventions with the goal of overcoming sunflower’s barriers to regeneration. Thus, the proposed research will deliver a toolkit of solutions for a major crop that currently lacks modern biotechnology tools to validate gene functions and accelerate breeding for traits essential to sunflower biology and agricultural production. The findings and methods from the proposed r