Isozyme-based genetic fingerprinting of Manihot sp

Abstract

Many cassava varieties have been released into farmers’ fields in Nigeria, but no reliable means in tracking their identity, thus causing multiple naming of these varieties. The methods used for identifying different cultivars of crop plants are based conventionally on the phenotypic expressions of the plant, plant parts, seeds or mode of introduction. The objectives of this study were to establish a reliable means of identifying cassava genotypes in in farmers’ fields based on isozyme analysis. Thirty- two cassava genotypes comprising of IITA elite cultivars, local landraces and adapted farmers’ varieties were planted at a spacing of 1m x 1m in a randomized complete block design in two replications.. Three morphological clusters were observed at 0.44, 0.497, and 0.497 levels of coefficient of similarity. The stem and petiole colours were observed as dominant traits in cassava classification. There are 3, 8, 9 and 11 loci for SKDH, 6-PGD, AAT and G-6-PDH, respectively, while isozyme markers 6-PGD, AAT and G-6-PDH revealed more polymorphism in cassava classification. These results imply important information for cassava population development and improvement that can be exploited by breeder.

Key words: Isozyme markers, genotypes, classification, morphology and polymorphism