Chromosome number and DNA content in callus culture ofCostus speciosus (Koen.) Sm.

Abstract

Karyological changes in the callus tissue of Costus speciosus (Koen.) Sm. at different ages have been analysed both by counting chromosome number and quantitating DNA content through cytophotometry. The cultures had been established from the tuber and maintained in modified Murashige and Skoog's basal medium (Physiol. Plant. 15: 473-497, 1962) supplemented with 2,4-D, NAA and BAP. Abnormality in chromosome behaviour leading to the formation of hypo-and hyperdiploid cells along with the diploid cells was observed. The abnormalities reached an optimum at different ages of the callus followed by a decline which varied amongst three populations. The frequency of hyperdiploid cells was higher than that of the hypodiploids. The role of endomitotic replication as well as non-disjunction of chromosomes resulting in the variation in chromosome number has been suggested. This was supported by the nuclear DNA value in successive passages. A difference in average amount of nuclear DNA with increase in age of the callus was recorded and the value also differed amongst these populations.

High Frequency in vitro Propagation Through Somatic Embryogenesis of Iphigenia indica Kunth et Benth, an Endangered Medicinal and Colchicines Yielding Herb of Commercial Interest

“…Chromosome analysis of the callus tissue and the regenerates were determined through aceticorcein staining squash technique (Mukhopadhyay and Sharma 1990). Ten root tips from each regenerate were stained and 25 well-scattered metaphase plates from each preparation were analyzed.…”