Genetic diversity in cassava based on agronomical, physiological and est-microsatellite markers under moisture stress conditions

Abstract

Genetic diversity of 23 cassava accessions was studied using agro-physiological and  EST-Microsatellite markers. Based on agronomical and physiological parameters the genotypes were classified into 6 clusters. Cluster-2 had highly 10 genotypes while the clusters-5 and 6 had single accession. The high yielding and highly drought tolerant genotype 8S501 stood alone in cluster-5. It had high cluster mean values for majority of the traits. The genotypes present in cluster-4 & 5 and cluster-1 & 2 were divergent and hybridization between these two groups may result in superior genotypes for drought tolerance. The EST-Microsatellites obtained from drought transcriptome of cassava showed that the mean number of alleles per locus was 1.81 with an average size of 217.7 basepairs (bp). The locus, MeESSR47 (Thylakoid membrane phosphoprotein 14 kDa, chloroplast precursor, putative), had more heterozygosity (0.387) and Shannon’s Index (0.575) among all the loci. These results cumulatively showed the low polymorphism in the EST regions of cassava DNA. The dendrogram showed 4 clusters based on EST Microsatellite diversity. The microsatellite based cluster classification of genotypes did not follow the diversity based on agronomical traits under moisture stress condition. A weak correlation revealed by Mantel test also indicated that there was no relation between agronomical and molecular diversity.