Microrhizome-Derived Somatic Embryogenesis: A Model System for the Illustration of Embryo Development in Aloe vera L

The intricate combinatorial chemistry of bioactive components in the Aloe vera L. gel makes industrial-scale production through chemical synthesis or microbial fermentation impractical. This reliance on natural plant sources is compounded by challenges in genetic improvement, as traditional breeding methods are ineffective due to seedless varieties and an asexual mode of propagation. Regeneration from a single transformed cell through somatic embryogenesis is a prerequisite of any genetic engineering programme, yet it has not been reported before. The present research illustrated in vitro shoot and microrhizome formation from field-grown rhizome, direct and indirect somatic embryogenesis from thin cell layer microrhizome, genetic homogeneity assessment, and field transplantation for the first time. The study optimized exogenous auxins, cytokinin, sucrose levels, and photoperiods across all growth stages. Morpho-histological study at different stages of regenerated cultures revealed the occurrence of direct and indirect somatic embryogenesis from the epidermis of the explant and from the morphogenic meristem inside callus tissue respectively. This work provides the first detailed study of different steps of cellular and organ differentiation from asymmetric cell division (ACD) in a monocot species using somatic embryogenesis, addressing a knowledge gap since zygotic embryogenesis in Aloe vera is not described. The key developmental stages included spherical, globular, and club-shaped pro-embryos; formation of bipolar embryos with distinct periderm, ground meristem, vascular tissues and organs like scutellum, coleoptile, hypocotyl, plumule, and root system. This research will contribute to understanding the developmental biology of monocot embryogenesis and support genetic improvement efforts to enhance bioactive compound production in Aloe vera.