Genetic diversity analysis of rambutan (Nephelium lappaceum L.) collections from Kerala using microsatellite molecular markers

  Full text PDF

Rambutan (Nephelium lappaceum L.) cultivation shows promising potential in Kerala, a tropical region in India known for its diverse agricultural practices; however, despite existing morphological characterization and diversity studies of local collections, comprehensive genetic diversity analysis using molecular markers remains lacking in the country. This research, conducted between 2021 and 2023, aimed to fill this gap by assessing the genetic diversity of twenty rambutan collections from the major rambutan growing regions in Kerala using SSR molecular markers. DNA isolation was performed using CTAB with minor modifications to obtain high-quality DNA samples. A sorbitol buffer pre-wash was done to improve the DNA quality. From 16 SSR primers screened, five were selected based on reproducibility and distinct banding patterns. These primers exhibited 100 % polymorphism, with polymorphic information content values ranging from 0.60 to 0.72, indicating their informativeness. The marker index, which measures primer utility, ranged from 1.80 to 2.88. Cluster analysis revealed two major clusters at a similarity coefficient of 0.70, with Cluster I comprising eight accessions and Cluster II comprising 12 genotypes. Principal coordinate analysis confirmed this clustering pattern. Genetic diversity ranged from 61 % to 70 % among the studied accessions, with collections from the same area exhibiting closer genetic distances, indicating possible dispersal from related parents. This study provides valuable foundational information for future crop improvement programs and marker-assisted breeding initiatives for rambutan in Kerala.