Effect Of Gamma Irradiation Mutagenesis On Diversity Of Cassava Tissue Culture Plantlets

Abstract

Cassava, Manihot esculenta Crantz (Euphorbiaceae), is one of the leading food and feed plants of the world and stands as the 3rd largest source of carbohydrates for human consumption after rice and maize. However, the cassava sub-sector has not realized its full growth in terms of commercialization and utilization. It is evidenced that the tuber crop can enhance the food base of the poor, increase their income and mitigate poverty among rural households but challenge of diseases and pest hamper its performance. Mutation and efficiency enhancing techniques have been shown to improve resistance in crops through increased diversity from which desired selections can be made. This study was aimed at development of tissue culture generated mutant populations of cassava mosaic virus (CMV) resistant cassava through gamma irradiation and in-vitro selection. Tissue cultured plantlets of farmer and consumer preferred but CMV susceptible cassava variety KM-1 were irradiated with gamma rays at 15Gy and the mutagenised population subcultured 4 times to M1V3 to eliminate chimera. Selected putative mutants were screened for effect of mutagenesis, in comparison with the parent variety. The assessed parameters included plant height through the first growth period, number of nodes, leaf morphology (number of leaf lobes) and colour of petiole. The data was collected after every fortnight for 2 months. Results showed that the mutant selections differred among themselves as well as from the parent variety in the assessed paramenters. The lobes for the parent variety were 5 while for the mutant population these raged from 4 to 9 and the differences were found to be significant. There was no significant difference in the petiole colours