Abstract
The efficient regeneration of plants from commercial genotypes is a pre-requisite for successful genetic transformation, to apply modern crop improvement techniques such as CRISPR-based genome editing. Plant regeneration through the somatic embryogenesis pathway offers an advantage over the organogenesis approach, avoiding the risk of developing chimeras. Plant genotype, explant type, and media compositions play an essential role in the in-vitro regeneration of plants. This study aimed to characterize the commercially grown Australian soybean genotypes for their potential to induce somatic embryos, embryo proliferation, maturation, germination, and plant regeneration. Overall, nine soybean cultivars belonging to different maturity groups were evaluated. Immature cotyledon ranging from 2-4 and 4-6 mm in size were used as explants for somatic embryogenesis induction. Maximum somatic embryo induction frequency (86%) was observed from 4-6 mm immature cotyledons of the cv. Jack (MG III), followed by 66%, 26%, 21%, and 6% in cultivars Williams (MG III), Snowy (MG III), MoonB1 (MG V), and PNR791 (MG V), respectively. On the other hand, cv. Snowy showed maximum somatic-embryo-inducing potential (67%) in 2-4 mm immature cotyledons followed by Williams, Jack, MoonB1, and PNR791. Somatic embryos from Jack, Williams, and Snowy cultivars were further tested for embryo proliferation, maturation, and germination. Maximum proliferation and maturation were observed in cv. Jack, followed by Snowy and Williams. However, cv. Snowy showed a significantly higher conversion of cotyledonary stage embryos to plantlets (85%), than both Jack and Williams cultivars (53% each). In conclusion, this study outlined a protocol for somatic embryogenesis and plant regeneration from three soybean cultivars. Our findings suggest commercial cv. Snowy could be a good candidate for developing transgenic plants through somatic embryogenesis.