Mammalian growth factors enhance regeneration in transgenic tomato lines

Genome editing technologies are now available for many crop species, greatly enhancing our ability to investigate gene function and transforming the field of plant transgenesis. However, the capacity to regenerate whole plants from cell culture remains a major limiting factor in many crops. Even in species with regeneration potential, certain genotypes remain recalcitrant. The physiological state of plant cells plays a central role in growth and development and is closely associated with kinase-mediated signaling networks. Notably, several defense-related genes activated during cellular repair processes following transgenesis share significant homology with mammalian defense genes. In this study, we evaluated whether supplementation with three mammalian growth factors could enhance regeneration efficiency in tomato. We selected two cytokines and a pro-inflamatory factor showing homology with plant kinase genes. We compared the percentage of transgenic plants generated through CRISPR-Cas9-mediated mutagenesis of four genes involved in sugar and organic acid metabolism across six tomato lines exhibiting varying regeneration capacities. Over three years of transformation experiments, we demonstrated that the addition of mammalian growth factors during transgenesis significantly improved regeneration frequency, particularly in recalcitrant tomato genotypes. Furthermore, growth factor supplementation not only enhanced transformation efficiency in difficult-to-transform lines but also increased the production of stable secondary lines.