Cytology of root tips of Dioscoreophyllum cumminsii (STAPF) diel

Abstract

Dioscoreophyllum cumminsii is a tropical dioecious rainforest vine. It grows in humid and heavily shaded understorey vegetation of closed forest, from May to October. The fruit, serendipity berry, contains a protein sweetener called monellin that could replace sugar in foods for diabetics and dieters. Other parts of the plant, for example, tubers, stems and leaves have medicinal values. This work was set up to study the mitotic chromosomes of root tips of D. cumminsii and establish the number of chromosomes in the genome. This is necessary since it appears that there is no published work on the chromosome number and structure of this important plant. The study was carried out at the Cytology Laboratory of the Department of Botany, University of Nigeria Nsukka. Root tips for the chromosome work were obtained from three sources: runners originating from main vine; sprouting pieces of tubers and redifferentiated root tips from callus. The results showed that normal metaphase plates of root tips of D. cumminsii contained sixteen chromosomes, 2n = 16. These chromosomes showed variations in size based on centromeric positions giving rise to metacentric and sub-metacentric chromosomes. Metaphase cells with more than 16 chromosomes were encountered from root tips regenerated in vitro from callus cells. This cytological knowledge is useful for future micropropagation or breeding activities involving D. cumminsii.

Keywords: Aneuploids, Euploids, Monellin, Protein sweetener, Redifferentiation

Agro-Science Vol. 4 (1) 2005: pp. 43-45