SSR DNA marker aided genetic diversity assessment of selected willow clones

Abstract

Around 100 clones of tree willows were subjected for nursery screening twice on morphometric traits. Genetic diversity was assessed in twenty-five genetically superior willow clones hailing from six countries using 16 SSR primers. Fourteen primers amplified the DNA but only ten showed polymorphism. Total 34 bands were scored, out of that 27 were found to be polymorphic and 7 were monomorphic. Three primers showed 100% polymorphism whereas 79.4% polymorphism was recorded in total. The dendrogram obtained from SSR markers revealed that clone SE-69-002 (S. matsudana) and NZ-1040 (S. matsudana X S. alba) as most similar clones (Jaccards coefficient of 0.97), and clone PN-721(S. matsudana X S. alba) and PN-731 (S. nigra), as most divergent clones (Jaccards coefficient of 0.63). All the genotypes were grouped into 4 distinct clusters. On the basis of similarity coefficient analysis the first cluster comprised of 11 genotypes, the second cluster have 8 genotypes where as third one has only one genotype and fourth cluster retained five genotypes. The clustering pattern further indicated that the geographic distribution may not be the reflection of genetic diversity in willow clones. Genotypes with high molecular diversity could be used in breeding programme in order to obtain heterotic hybrids and development of gene pools with broad genetic base. The genotype specific bands developed by the SSR primers could also be used for identification of cultivar.