Molecular Assessment of <i>Cocos nucifera</i> L. Var. Sri Lanka Yellow Dwarf for Genetic Purity and <i>Aceria</i> Mite Tolerance

Abstract

World-over, coconut is classified broadly into tall and dwarf phenotypes. The dwarf coconut variety is further divided into forms based on the colour of the epicarp. The Sri Lanka Yellow Dwarf (SLYD) coconut variety was observed to have individuals of differing phenotypes and this variety also showed varying degrees of tolerance to Aceria guerreronis (Keifer), which is a pest infesting coconut causing economic losses. This study was aimed at the evaluation of the coconut form SLYD for varietal confirmation and the tolerance to Aceria mite at the microsatellite marker loci. Twenty five sample palms drawn randomly from four morphological groups based on stature and tolerance to Aceria mite were genotyped at seven SSR marker loci along with Sri Lanka Tall (SLT) and Sri Lanka Green Dwarf (SLGD) as reference varieties. Three SSR loci were highly informative for the SLYD population and the results revealed the presence of a population structure within the SLYD coconut population. A clear clustering was observed for tall like and the dwarf like groups with more variation within the tall like group. Clear allelic identifications were established at several SSR loci for the clustering based on stature and the markers were identified for distinguishing different groups. The study provided evidence for the need for reclassification and purification of SLYD coconut population. Certain associations were present for the character Aceria mite tolerance, indicating the potential for marker assisted selection.