Characterisation of Sri Lanka Yellow Dwarf Coconut (Cocos nucifera L.) by DNA fingerprinting with SSR markers

Coconut (Cocos nucifera L.) is classified into three main varieties in Sri Lanka as tall, dwarf and intermediate with each variety including several forms of coconut. Sri Lanka Yellow Dwarf (SLYD) is a coconut form included under the variety dwarf and it is a parent of the improved coconut hybrid CRIC65. Morphological differentiation of SLYD from Sri Lanka Yellow Semi Tall (SLYST) and a mixed morphological group (ML) of SLYD and SLYST is impossible at the seedling stage. The objective of the present study was to derive DNA fingerprints for SLYD and SLYST for distinct identification at any stage during its life cycle. A total of 30 palms were genotyped with sixteen polymorphic SSR primer pairs and data were analysed with the PowerMarker V3.25 software. The results revealed SLYD specific DNA fingerprints at SSR loci CAC65, CAC4, CNZ10, CnCirD8 and CNZ6. These markers scored specific homozygous alleles for SLYD with very high allelic frequency, and scored very low frequencies in SLYST and ML phenotypes. SLYD formed a clear separate cluster in the UPGMA dendrogram while SLYST and ML formed separate mixed clusters. Thus the present study was successful in generating specific DNA fingerprints for SLYD and this information will be of practical use in differentiating SLYD at the seedling stage, especially in the establishment of isolated coconut seed gardens for mass production of improved coconut cultivars having SLYD as a parent.