Population structures of Brazilian tall coconut (Cocos nucifera L.) by microsatellite markers

Coconut palms of the Tall group were introduced to Brazil from the Cape Verde Islands in 1553. The present study sought to evaluate the genetic diversity among and within Brazilian Tall coconut populations. Samples were collected of 195 trees from 10 populations. Genetic diversity was accessed by investigating 13 simple sequence repeats (SSR) loci. This provided a total of 68 alleles, ranging from 2 to 13 alleles per locus, with an average of 5.23. The mean values of gene diversity (H-e) and observed heterozygosity (H-o) were 0.459 and 0.443, respectively. The genetic differentiation among populations was estimated at (theta) over cap (p) = 0.1600 and the estimated apparent outcrossing rate was t(a) = 0.92. Estimates of genetic distances between the populations varied from 0.034 to 0.390. Genetic distance and the corresponding clustering analysis indicate the formation of two groups. The first consists of the Baia Formosa, Georgino Avelino, and Sao Jose do Mipibu populations and the second consists of the Japoata, Pacatuba, and Praia do Forte populations. The correlation matrix between genetic and geographic distances was positive and significant at a 1% probability. Taken together, our results suggest a spatial structuring of the genetic variability among the populations. Geographically closer populations exhibited greater similarities.