The efficient plant genetic transformation system mediated by FELBs and RTBs respectively via novel somatic embryogenesis in Allium sativum

Introduction Somatic embryogenesis represents an indirect but highly efficient biotechnological method for plant regeneration, genetic transformation, and virus-free propagation. Methods Herein, we investigated the effects of NAA, 2,4-D, and TDZ on the morphogenic capacity of Allium sativum . This is evaluated in terms of the formation of frog egg-like body and rhizoid tuber morphological structures, somatic embryo development, shoot regeneration, and the genetic transformation method. Results Two novel high-efficiency SE systems in garlic were characterized, operating through the FELB and RTB pathways, respectively, with a focus on the regulatory effects of plant growth regulators (PGRs) on SE progression. In the FELB pathway, somatic embryos were highly induced from root explants, achieving an induction rate of 96.33%. Embryoid development was successfully accomplished using a combination of 2.5 mg/L NAA and 2.5 mg/L 2,4-D under dark conditions. Furthermore, 5.0 mg/L BAP was identified as the optimal cytokinin concentration for plant regeneration via the FELB pathway. In the RTB pathway, somatic embryos were also efficiently induced from root explants; under sucrose semistarvation conditions, the average number of RTBs induced per explant reached 44.067. Embryoid development in the RTB pathway was achieved with 10 mg/L NAA under dark conditions combined with 20.0 mg/L TDZ under light conditions (180 µmol·m -2 s -1 ), a combination that significantly promoted RTB formation. Isolated RTBs were successfully germinated on MS medium supplemented with 2.5 mg/L BAP. This study is the first to reveal that the developmental stages and ontogenetic processes of FELBs and RTBs in the monocotyledonous plant garlic exhibit striking homology to those reported in dicotyledonous species. Using RcLEC1-B as a reporter gene, we confirmed the successful establishment of FELB/RTB-mediated genetic transformation; the TCS gene was further introduced to enhance garlic resistance against Penicillium chrysogenum and Phytophthora porri . Discussion Collectively, our findings establish novel methodologies for garlic SE and transgenic manipulation, providing valuable tools for the genetic improvement of this economically important crop.