Analysis of genetic diversity in coconut and its conservation in root (wilt) disease affected areas of Kerala: A community participatory approach

Abstract

Root (wilt) disease is a major constraint to coconut production in Kerala State. Conserving ecotypes with resistance or tolerance to the disease on a community basis is essential to sustain coconut production in the root (wilt) disease prevalent areas. Three communities’viz., Pathiyoor and Devikulangara (Alappuzha District) and Thodiyoor (Kollam District) were selected and a survey was conducted with the participation of stakeholders, to characterize the local coconut ecotypes. Six ecotypes comprising of four talls and two dwarfs were identified and morphological data revealed that the local ‘Jappanan’ ecotype closely resembled Evoor Green Tall ecotype. Simple Sequence Repeat (SSR) analysis in 90 selected coconut palms representing the six ecotypes using 14 markers indicated that the observed heterozygosity was higher in tall ecotypes (0.179-0.365) compared to the dwarfs (0.03-0.07). Lower values for observed heterozygosity compared to the expected heterozygosity in tall ecotypes are indications of genetic basis for disease resistance observed in diseasefree mother palms. Molecular characterization helped in identifying diverse coconut ecotypes having application in production of vigorous hybrids. In the dendrogram constructed using nut character data, three of the tall ecotypes (Green Tall, Brown Tall and Brick Red Tall) clustered together whereas ‘Jappanan’ clustered separately. Mantel’s correlation test using the ZT software revealed significant correlation (0.96) between the SSR data and morphological data.