Genetic and epigenetic alterations associated with somatic embryogenesis in Argania spinosa

Abstract Expanding the habitat of the Morocco’s endemic species, Argania spinosa L., using high-quality, true-to-type plants has become essential. Somatic embryogenesis represents a biotechnological tool for capturing the genetic advantages of selected elite genotypes for their clonal propagation. This approach could support either forest reforestation or the establishment of new orchards dedicated to high-quality oil production. Therefore, this study focuses on evaluating the potential for somatic embryogenesis in this multipurpose tree. Our primary objective was to optimize culture conditions using various plant growth regulators and adjuvants. In addition, considering the species’ inherent resistance to in vitro stimuli, we explored a pharmacological approach using 5-Azacytidine treatments on leaf explants to induce DNA hypomethylation. This approach aimed to investigate its impact on the key embryogenesis-related genes and epigenetic regulators involved in the somatic embryogenesis process, which were identified for the first time in the argan genome. Our results indicated that the treatment without 5-Azacytidine showed no signs of embryogenesis. In contrast, the application of 20 µM 5-Azacytidine for seven days had a positive effect on the expression levels of embryogenesis-related genes. This treatment notably increased the expression of BABY BOOM ( AsBBM ) and WUSCHEL RELATED HOMEOBOX 4 ( AsWOX4 ). DNA hypomethylation induced changes in the expression of genes associated with epigenetic regulation, including PICKLE ( AsPKL ) and components of the Polycomb Repressive Complex, specifically Curly Leaf ( AsCLF ) and Like Heterochromatin Protein ( AsLHP ), which mediate histone methylation, leading to chromatin remodeling and cell reprogramming during somatic embryogenesis induction. The findings suggest that DNA methylation, Polycomb-mediated histone methylation, and PKL -related chromatin remodeling are crucial for inducing totipotency in somatic cells and achieving somatic embryogenesis in recalcitrant materials.