Genetic diversity of the Sri Lanka Yellow Dwarf coconut form as revealed by microsatellite markers.

Sri Lanka Yellow Dwarf (SLYD) is an important coconut form as a parent in the national coconut breeding programme of Sri Lanka. Though dwarf coconuts are known to be purelines, SLYD displays uncharacteristic morphologies. The current research was conducted to characterize a sample of 15 SLYD individuals using 10 SSR marker loci to determine the genetic diversity within the form. One palm each of Sri Lanka Tall (SLT), Green Dwarf (GD) and Gon Thembili Tall (GT) were used as reference coconut forms. Genomic DNA was extracted and PCR amplification was performed followed by 6% denaturing polyacrylamide gel electrophoresis to visualize the bands. Genotypic data were analysed using PowerMarker software. All ten marker loci were polymorphic, and among them more informative microsatellite loci for the tested population were identified. A total of 34 alleles were scored in the 15 individuals of SLYD ranging from a minimum of two to a maximum of five and a total of 22 heterozygous loci were identified spreading across the ten marker loci. The results indicated the SLYD to share bands more frequently with tall coconut forms than GD. The dendrogram displayed three clusters of SLYD with one group including comparative form GD and another cluster including both SLT and GT. The observed heterozygosity, and genetic and allelic diversities exceed the levels that can be expected from dwarf coconut forms which are self-breeding purelines. It is recommended to purify SLYD coconut form to ensure genetic purity of SLYD parental palm pool in Sri Lanka. Tropical Agricultural Research Vol. 26 (1): 131 – 139 (2014)