Comparative Evaluation of Soybean Genotypes for In Vitro Regeneration via Direct Organogenesis

Genetic transformation plays a vital role in enhancing crop performance under changing climatic conditions. However, soybean (Glycine max L.) remains a transformation-recalcitrant species, with regeneration efficiency strongly influenced by genotype, explant type, and in vitro culture conditions. In this study, four soybean genotypes: Faisal Soybean, AARI Soybean, Rawal-I, and Williams-82 were evaluated for their regeneration potential via direct organogenesis using half-split cotyledonary explants. Explants were cultured on Murashige and Skoog (MS) medium supplemented with varying concentrations of benzyl amino purine (BAP) and naphthalene acetic acid (NAA) for shoot induction, and indole-3-butyric acid (IBA) and indole-3-acetic acid (IAA) for root induction. Among the tested genotypes, Faisal Soybean exhibited the highest regeneration efficiency, with 40.13% shoot induction and 26.83% root induction, followed by AARI Soybean. The optimal shoot induction was achieved on MS medium containing 2.0 mg·L−1 BAP + 0.1 mg·L−1 NAA, while the highest root induction was observed on medium with 0.5 mg·L−1 IBA + 1.2 mg·L−1 IAA. In contrast, Rawal-I showed the lowest regeneration response across all stages. These findings highlight significant genotype-dependent variation in regeneration potential, reinforcing the importance of selecting responsive cultivars for transformation. The optimized protocol developed in this study provides a reliable foundation for future genetic transformation and crop improvement efforts in soybean.