Parenchymal motor cells of pulvini base: An ideal explant for efficient direct regeneration in white poplar

Objective: Poplars (Populus sp.) are the most industrially important woody plants, garnering significant global attention for the introduction of new traits using genetic engineering and gene/genome editing approaches. However, the efficacy of genetic transformation and regeneration response of plant explants remains challenging among Populus species due to high variation in their genetic background. This work aimed to identify an optimal explant source to enhance high-frequency genetic transformation and genome editing capabilities in white poplar.Methods: Transverse and longitudinal thin cell layer (t/lTCL) explants from Populus alba L. pulvinus and stem tissues were cultured on the shoot induction media with varying concentrations of BAP (۰, ۰.۲۵, ۰.۵, ۰.۷۵, and ۱.۰ mg/L) in combination with IBA/NAA (۰, ۰.۲۵, ۰.۵, and ۰.۷۵ mg/L) to evaluate their regeneration potential. The effect of node position on pulvini-tTCL regeneration was assessed, and histological analysis was performed on highly responsive explants. The root induction was examined using media with graded levels of IBA (۰, ۰.۱, ۰.۲, ۰.۳ mg/L) and NAA (۰, ۰.۰۵, ۰.۱, ۰.۱۵, and ۰.۲ mg/L).Results: We obtained the fast and highly responsive tTCL-mediated shoot regeneration from the parenchyma cell layers (۴۰۰-۵۰۰ µm thickness) of the pulvinus basis of the ۴th node cultured on shoot induction medium containing BAP ۰.۷۵ mg/L and IBA ۰.۵ mg/L, with a mean of ۴۳.۵۹ ± ۰.۲۲ shoots per explant. The regenerated shoots were well-rooted in root induction medium containing IBA ۰.۲ mg/L and NAA ۰.۱ mg/L. The well-hardened plants were transferred to greenhouse conditions.Conclusion: The superior capacity of pulvini-tTCL tissue provides an opportunity to achieve high-frequency transgenic white poplar in genetic engineering and genome editing approaches.

کلیدواژه ها:

Direct organogenesis ، Microscopy analysis ، Populus alba ، Pulvinus ، Thin cell layer ، Tissue maturity culture ، tTCL