Genetic diversity analysis of cyanogenic potential (CNp) of root among improved genotypes of cassava using simple sequence repeat markers

Abstract

^<*nogeni c potential (CNp) of cassava constitutes a S C r *° u s problem for over 500 million people who rely *he crop as their main source of calories. Genetic •^fcrsity is a key to successful crop improvement for Redin g new improved variability for target traits, ^ny-lhree improved genotypes of cassava developed •J International Institute of Tropical Agriculture (IITA), ^**iaru were characterized for C Np trait using 35 Simple Sequence. Repeat (SSR) markers. Essential colorimetry P»cric test was used for evaluation of CNp on a color scale of 1 to 14. The CNp scores obtained ranged from 3 to 9, with a mean score of 5.48 (± 0.09) based on Statistical Analysis System (SAS) package. TMS M98/ 0068 (4.0 ±0.25) was identified as the best genotype with low C N p while TMS M98/0028 (7.75 ±0.25) was the worst. The 43 genotypes were assigned into 7 phenotypic groups based on rank-sum analysis in SAS. Dissimilarity analysis representatives for windows generated a phylogenetic tree with 5 clusters which represented hybridizing groups. Each of the clusters (except 4) contained low CNp genotypes that could be used for improving the high C Np genotypes in the same or near cluster. The scatter plot of the genotypes showed that there was little or no demarcation for phenotypic C Np groupings in the molecular groupings. The result of this study demonstrated that SSR markers are powerful tools for the assessment of genetic variability, and proper identification and selection of parents for genetic improvement of low C Np trait among the IITA cassava collection.