Cytological analysis of embryogenic callus and regenerated plants of Urginea Indica Kunth., Indian squill

Abstract

Friable calli were induced from bulb scale explants of diploid (2 n = 20) Indian squill, Urginea indica Kunth. Embryogenic calli were formed when one year old friable calli were allowed to remain on the high 2,4-D medium for a prolonged period. The original explant, friable calli, somatic embryos and plant regenerated via somatic embryogenesis were examined cytologically. The original explant had a negligible level of DNA variation. The dedifferentiating calli showed complete elimination of diploid cells after 6 months and friable calli were composed of cells with high chromosome number (100–300). Embryogenic calli contained large and small cells, the latter with deeply stained nuclei, showing variable ploidy (6n-12n). Globular embryoids were also composed of polyploid cells, with chromosome numbers ranging from 40–90 with a few highly polyploid cells (< 160). Among about a thousand plants regenerated from these friable embryogenic cultures, chromosome numbers of 150 plants were determined. All plants were polyploid. About 50% of the plants were octaploid; 6% were predominantly hexaploid and rest were of variable ploidy. The results show that highly polyploid cells are capable of forming somatic embryoids and regeneration. © 1989 Taylor & Francis Group, LLC.