Original Articles

Genetic distance analysis of elite cassava (Manihot esculenta Crantz) genotypes in Malawi using morphological and AFLP marker techniques

Published in: South African Journal of Plant and Soil
Volume 23, issue 1, 2006 , pages: 58–61
DOI: 10.1080/02571862.2006.10634731
Author(s): I., R.M. BenesiDepartment of Plant Sciences, South Africa, M.T. LabuschagneDepartment of Plant Sciences, South Africa, A., G.O. Dixon, Nigeria, C.D. ViljoenDepartment of Plant Sciences, South Africa, N.M. Mahungu, Malawi

Abstract

Cassava is the second most important staple food crop in Sub-Saharan Africa and is also an important food and cash crop in Malawi. A prerequisite for any genetic improvement programme is knowledge of the extent of genetic variation present between cultivars and genetic distances between them. This can be achieved through characterisation of germplasm using morphological, biochemical or DNA markers. This study was done to determine the genetic relatedness of commercial Malawi cassava varieties and promising clones using AFLP DNA markers and morphological descriptors, and to compare these methods in characterising cassava genotypes. Trials with 16 cassava genotypes were planted at Chitedze and Makoka in Malawi. Morphological characterisation was done during plant growth and at harvest. This study revealed that the genetic distances for the local cultivars, locally bred clones and introduced genotypes were divergent. This is supported by the distribution of the genotypes in different clusters despite their origin. Genetic distances determined by morphological characterisation correlated to those determined from AFLP fingerprinting. It is however, a prerequisite that morphological characterisation be based on salient traits, and the conversion of the morphologic data into binary characters needs careful consideration to achieve meaningful results.

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