Genetic Characterization of Ghanaian Avocados Using Microsatellite Markers

The origin, horticultural race and genetic relationship among Ghanaian avocado (Persea americana Mill.) seedlings were studied. A population of 172 avocado samples, selected from farmers' fields and backyards, Were genotyped using 12 simple sequence repeat markers. Representatives of the three horticultural races served as outliers in this study. An average 4.42 alleles per locus were elucidated across all populations. The average expected heterozygosity, H, (0.51), was 41.7% greater than the observed heterozygosity, R. (0.36), depicting heterozygote deficiency and a high level of homogeneity or inbreeding within the entire Ghanaian population. The genetic distances between the Ghanaian subpopulation pairs was low (0.00 to 0.07), further supporting a high level of homogeneity and suggesting either very few founder parents or a high proportion of founders with very little genetic variability. The phylogenetic tree generated reaffirmed the high genetic similarity among the Ghanaian seedlings with only 8.7% clustering separately. The Ghanaian population also was found to be genetically more closely related to the West Indian representatives but distinct from the Mexican and the Guatemalan accessions, proposing that either most of the founders may have been of the West Indian race or founders of the other races may not have survived the harsh tropical conditions of Ghana. It is suggested that enlarging Ghana's avocado gene pool by introducing various elite cultivars Will improve the avocado industry in this country.