Molecular Characterization of Sapota Genotypes Using RAPD Markers

PCR-based Random Amplified Polymorphic DNA (RAPD) markers were used to study the characterization of 31 accessions of sapota comprising 19 cultivars, 6 landraces and 6 hybrids. DNA isolated by CTAB method was used for amplification of 48 markers by using 7 RAPD primers (OPA 04, OPB 03, OPB 06, OPB 08, OPC 02, OPC 08, and OPC 05). All 48 polymorphic fragments were used to generate the similarity matrix and construct a dendrogram. In this matrix highest genetic similarity of 100% was observed between the 'DHS-1' and 'DHS-2', while the least (23%) was between 'PKM-3' and 'Culcutta Round'. UPGMA (unweighted pair group method with arithmetical averages) cluster analysis using Jaccard's coefficient of similarity of 31 genotypes showed medium to high diversity, which are distributed between the ranges of 35-100%. Maximum genetic similarity distance between 'Oval' and 'Murabba' (91%), whereas minimum genetic similarity distance was 35% between 'PKM-5' and 'Mohangootee'. The clustering revealed that all round and oval shape fruit bearing genotypes are grouped together and oblong shape fruit bearing genotypes are grouped together. The oblong shape fruit bearing genotypes are narrowly associated with the round and oval-shaped fruit bearing genotypes, which are 'PKM-4', 'Culcutta Round', 'PKM-3' and 'Mohangootee'. All these genotypes are having oblong-shaped fruit, except 'Culcutta Round', whereas 'PKM-5' has been made distinctive cluster in the dendrogram because of its distinctive oblong-shaped fruit, which is closely associated with 'PKM-4', 'PKM-3' and 'Mohangootee'.