Genetic Diversity Analysis of the Wild Coffea arabica L. Populations From Harenna Forest, Bale Mountains of Ethiopia, Using Inter Simple Sequence Repeats (ISSR) Marker

Abstract

In spite of their importance, the level and distribution of wild Coffea arabica L. in Harrena has not been extensively examined in depth with molecular markers. The current study was conducted on the wild Arabica coffee of the Harenna Forest of Bale Mountain, southeast part of Ethiopian. The levels and distribution of within and among populations genetic diversity of one hundred wild Coffea arabica L individuals, representing four populations: two from semidisturbed (Bale-I and Bale-3) and two from undisturbed (Bale-4 and Bale-6) regions of the forest, were collected and evaluated with Inter Simple Sequence Repeats (ISSR). A total of nine primers which contain different simple sequence repeat (SSR) were used and tested for PCR amplifications. A total of one hundred thirty seven bands were detected. The number of bands per ISSR markers ranges from ten to twenty one with an average of 15.2. These were then used to estimate the genetic diversity. Out of the total bands produced, 61(44.53%) were polymorphic and the number of polymorphic bands per ISSR markers ranges from one (1) to nineteen (19), with an averages of 6.77. The similarities between individual genotypes were estimated using UPGMA and NJ analysis. The populations were found to be clustered on the basis of their respective origin. The UPGMA cluster analysis showed that the four populations form two major clusters (undisturbed and semi-disturbed populations together) according to locations from which they were collected. The two major clusters further divided into two. Analysis of molecular variance (AMOVA) indicated that population level genetic diversity was relatively high (56.8%). Shannon’s diversity index showed the same patterns and indicated that the within and between populations genetic diversity of Coffea arabica L. populations are significantly different. A considerable proportion (83.6 %) of the total genetic diversity was distributed within populations (i.e., due to differences among individuals within the populations). 16.4% of the total genetic diversity was due to differences among populations. Such distributions of the total genetic diversity could be attributed to gene flow via insect pollinators, seed flow by wild animals, birds and human. Generally, on the basis of samples of 137 bands in the four populations, ISSR was able to reveal moderate to high levels of genetic diversity within and among wild coffee populations of Harenna Forest of Bale Mountain.