Full Length Research Paper

Characterization of Kenyan sweet potato genotypes for SPVD resistance and high dry matter content using simple sequence repeat markers

Karuri, H. W.¹, Ateka, E. M.¹*, Amata, R.², Nyende, A. B.¹ and Muigai, A. W. T.¹

¹Jomo Kenyatta University of Agriculture and Technology P. O. Box 62000, 00200, Nairobi, Kenya.

²Kenya Agricultural Research Institute. P. O. Box 14733, 00800 Nairobi, Kenya.

*Corresponding author. E-mail: eateka@agr.jkuat.ac.ke.

Accepted 20 February, 2009

Simple sequence repeat (SSR) markers were used to characterize Kenyan sweet potato genotypes for resistance to the sweet potato virus disease (SPVD) and high dry matter content. Eighty nine (89) genotypes with a mean symptom severity score of between 1 and 1.5 were selected following graft inoculation with SPVD-infected scions and characterized using 6 SSR primers. The 6 SSR primer pairs had an average polymorphic information content (PIC) of 0.47. The average number of alleles within the 89 genotypes across the 6 loci was 13.52. Cluster analyses revealed a 50% variation among the 89 genotypes. The dendrogram did not reveal any unique clustering of the genotypes according to dry matter content and reaction to SPVD. The genetic differences among the SPVD resistant genotypes and those with high dry matter revealed by the distinct groups suggest a significant genetic variability and the presence of different sources of resistance to SPVD and high dry matter. This characterization will give valuable information for breeders and serve as a baseline for efficient development of new cultivars resistant to SPVD and containing high dry matter.

Key words: Polymorphic information content, SPVD, severity, cluster analysis.