Challenges, Opportunities, and Emerging Perspectives in Eggplant Transformation and Genome Editing

Eggplant (Solanum melongena L.) is a major horticultural crop for which genetic transformation and genome editing could accelerate functional genomics and precision breeding, but their routine use remains constrained by regeneration recalcitrance, strong genotype dependence, and fragmented methodological reporting. This review critically assesses Agrobacterium-mediated transformation protocols, genome-editing studies, and emerging in planta virus-based approaches across the complete workflow, from explant preparation and nucleic-acid delivery to regeneration, selection, plant recovery, and outcome assessment. The major variables shaping transformation success are examined, including explant type and age, pre-culture, bacterial strain, infection and co-culture conditions, acetosyringone, regeneration medium, selection pressure, shoot recovery, rooting, and efficiency assessment. The evidence indicates that reported performance differences are difficult to interpret because studies often rely on genotype-specific optimization, incomplete methodological description, and non-equivalent efficiency metrics. Complementary strategies are also discussed, including virus-induced gene silencing, virus-induced gene editing, biolistics, protoplast delivery, floral dip-inspired approaches, highly regenerable model genotypes, and morphogenic regulators. Finally, the review outlines priorities to move eggplant biotechnology from proof-of-concept toward reproducible breeding pipelines: standardized reporting, direct protocol comparisons, genotype-aware optimization, mechanistic studies of recalcitrance, and transformation-competent reference lines. Although centered on eggplant, the methodological framework and reporting priorities identified here are relevant to other horticultural crops in which genotype-dependent regeneration limits genome engineering. Together, these priorities provide a roadmap from isolated proof-of-concept experiments to reproducible and breeding-relevant genome-editing pipelines.