Anatomical Changes during in Vitro Direct Formation of Shoot Bud from Root Tips in Garlic (Allium sativum L.)

In vitro direct shoot bud organogenesis from garlic (Allium sativum L. cv. White roppen) root tips was studied under a light microscope. In root tips cultured on the shoot induction medium that consisted of Murashige and Skoog basal salts and vitamins with 1 μM NAA and 10 μM BA, periclinal cell divisions were initiated in epidermal cells in the formative part or the distal elongation zone of the root apical meristem 6 to 8 days after the start of culture (day 6∼8). The periclinal cell divisions continued to form tiers of cells until day 12. Some of the cells divided anticlinally and formed protrusions of shoot primordia. Several shoot bud primordia developed within 16 days. Organized shoot apical meristems with leaf primordia were evident by day 20. The shoot bud formation in this study did not involve callus formation. The in vitro shoot bud formation from root tips could be efficientiy used for the rapid clonal propagation of garlic without changing the genetic fidelity. The implications of developmental pattern in direct bud regeneration are relevant in developing suitable regeneration systems and conducting critical physiological experiments