Evaluation of variability among breeding lines and cultivars of taro (Colocasia esculenta) in Papua New Guinea using ISSR fingerprinting and agro-morphological characterization

Abstract

Agro-morphological characterization and inter-simple sequence repeat (ISSR) DNA fingerprinting were used to evaluate variability among selected Papua New Guinean (PNG) taro (Colocasia esculenta) accessions. Twenty-three discriminatory descriptors selected from the International Plant Genetic Resources Institute (IPGRI, 1999) descriptor list were combined with ISSR markers to characterize 13 taro accessions. Genotyping data were obtained via polymerase chain reaction (PCR) with three ISSR primers: (GA)9AT, (GA)9AC and (ACC)6Y. Initial evaluation of the agro-morphological variation indicated that the total variation observed appeared to be associated with colours of corm flesh, corm cortex and petiole, stolon formation, corm shape, lamina orientation and lamina vein pattern. All genotypes were separated as distinct morphotypes, providing useful information for development of a minimum descriptor list. ISSR primers generated complex banding patterns, with primer (GA)9AC amplifying fewer but proportionately more (90%) polymorphic fragments. Fingerprinting with three ISSR primers enabled the identification of closely related genotypes and the separation of those that were distantly related. Little correlation was found in between the agro-morphological and molecular data in the clusters generated. However, the two types of data provided complementary information on the existing diversity and available genotypes that can be immediately used by the breeders.