Enhanced hairy root induction in garlic (Allium sativum L.) via Agrobacterium rhizogenes: Targeting the basal plate of intact sprout

Hairy root induction in garlic represents a promising approach to actively exploit biomass from a familiar plant species rich in antibacterial compounds. Previously, the stem disc region of garlic was identified as a potential site for morphogenesis; however, few studies have focused on utilizing this tissue for hairy root induction and optimizing the conditions to enhance transformation efficiency. Histological analysis revealed that the basal plate contains soft parenchyma tissue conducive to root and vascular development, making it a suitable target for transformation in monocot species. In this study, we investigated the factors influencing hairy root induction from this recalcitrant tissue. Our results indicated that maintaining the integrity of the basal plate of stem disc in 10-day-old garlic seedlings significantly enhanced induction efficiency compared to sectioning methods. Through preservation of the primary root system and inner clove tissue and addition of acetosyringone, roots exhibited further improved stability in genetic, morphological, and growth traits, with fresh biomass accumulation reaching 1 g per induced explant and the hairy-root induction rate achieved 100%. PCR analysis confirmed the presence of rolB and rolC genes in induced roots, verifying successful gene transfer by Agrobacterium rhizogenes ATCC 15834. Overall, this study provides important insights into improving hairy root induction in garlic-a monocotyledonous species typically considered recalcitrant-and highlights the stem disc as a reliable and efficient target tissue for generating bioactive root biomass. These findings not only advance transformation strategies in monocots but also open broader opportunities for metabolic engineering, enhanced production of valuable secondary metabolites, and the development of sustainable biotechnological platforms for pharmaceutical and agricultural applications.