Callus Development and Indirect Shoot Regeneration from Seedling Explants of Sugar Beet ( Beta vulgarisL.) Cultured In Vitro

For callus production, hypocotyl, cotyledon, petiole and leaf explants from seedlings of different sugar beet ( Beta vulgaris L.) breeding lines were cultured on MS medium containing BAP or KIN in combination with NAA or 2,4-D at 0.0, 0.5 or 1.0 mg/l. The use of both auxins in combination with 0.5 mg/l BAP or 0.5 mg/l KIN resulted in greater amounts of callus from all types of explants. However, hypocotyl and cotyledon explants produced significantly more callus than petiole and leaf explants when the means of all lines were taken into account. Two types of callus were usually obtained, white and friable callus with large cells (Type I) and green and compact callus with smaller cells (Type II). For shoot induction, Type I callus was transferred to MS medium containing 2.5 mg/l TDZ or 1.0 mg/l BAP in combination with 0.3 mg/l IAA, together with or without a cold pre-treatment at 4¡C for two weeks. More shoots developed from the pre-treated callus and elongated shoots could be readily rooted on MS medium containing 3.0 mg/l IBA.