PLANT REGENERATION FROM SUSPENSION CULTURES OF IRIS PUMILA L.

Abstract

A protocol for efficient plant regeneration of Iris pumila L. was developed via somatic embryogenesis and/or organogenesis from suspension cultures. Induction of embryogenic calli was achieved by leaf-base culture of in vitro grown plants on solid Murashige and Skoog (MS) medium supplemented with 3 % sucrose and (in mgL): inositol 100, pantothenic acid 10, nicotinic acid 5, vitamin B1 2, vitamin B6 1, casein hydrolysate 250, proline 250, 2,4-dichlorophenoxyacetic acid (2,4-D) and kinetin (1.0 mgL, each). Cell suspensions were established and maintained in MS liquid medium with the same content of 2,4-D and kinetin as used for induction and proliferation of embryogenic calli. After three subcultures stable suspension cultures were successfully established and maintained by subculturing every 3 weeks. The suspension cultures were initially composed of single cells, bi-, three and multicellular proembryos and cell aggregates. In prolonged suspension cultures (6-8 weeks) three types of embryogenic calli were observed: yellow, compact (Type I); yellow-green, friable (Type II) and white, friable (Type III). The effect of cytokinins (zeatin 0.05; 0.1; 0.2 and / or 6-benzylaminopurine-BAP, 0.1 and 1.0 mgL, respectively) on plant regeneration of these three types of calli were investigated. Friable (Type II and III) suspension derived calli have the highest morfogenic potential. During the regeneration process, two different regeneration pathways were observed: somatic embryogenesis and/or organogenesis dependent on used cytokinin. Germination of normally developed somatic embryos was achieved on MS solid medium without hormones. Potted plants of I. pumila grew normally and flowered.