Abstract:
Many studies reported wide genetic variability of Arabica coffee accessions collected from
Ethiopia compared with commercial cultivars demonstrating the great potential of these
accessions for future breeding purposes. However,little work has been done on the
molecular genetic structure and diversity of Ethiopian Arabica coffee populations. Hence,
this study was initiated with the objective of studying the genetic diversity of Coffea arabica
populationscollected from different regions of Ethiopia using SSR markers. A total of 20
SSR markers were used to genotype 86 accessions and produced a total of 112 alleles,
ranging from 3 to 11 with an average of 5.6 alleles per locus.All the loci across the entire
populations were found to be highly polymorphic and informative with PIC values ranging
from 0.45 to 0.75 with a mean of 0.6 confirming the good discriminatory power of the SSR
loci used.Average observed heterozygosity andallelic richness across all populations
ranged from (0.22-0.27 and 3.52-4.26), with a mean of 2.43 and 3.97, respectively. AMOVA
showed 63% of the variation to be within populations, 33% among individuals within
populations and 4% among population based on geographical origin.The smallerFst
(0.037) observed indicates the presence of lower population geneticdifferentiation as a
result of higher gene flow (Nm =2.45) between the C. arabica populations. The lowest mean
genetic distance observed between C. arabica populations was 0.21. The populations from
Bale and Hararge were highly distant from other populations.The unweighted pair group
methods with arithmetic meanbased cluster analysis and principal coordinate analysis
poorly grouped the individuals into distinct clusters confirming the presence of population
admixture due to the long distance movement of C. arabica seeds and high gene flow among
populations of adjacent geographical regions. The observed higher genetic variability in all
populations indicates that the country has huge coffee genetic diversity which can serve
coffee improvement.Comparatively, the populations from Omo, Ilubabor and Benchi Maji
were more diverse than other populations. Thus, special attention on these populations may
be useful in future Coffea arabica breeding program, germplasm conservation.
