Molecular identity for commercially important inter-specific hybrids of Coffea using ISSR-DNA marker: implication on genetic improvement

Six popular and widely cultivated arabica coffee (Coffea arabica L.) varieties of commercial importance namely Selection 5B, Selection 13, Selection 11, Selection 8, Selection 7.3 and Selection 3 were tested for their genetic identity with ISSR markers. Fifteen ISSR primers were tested using genomic DNA of selected coffee varieties. Pooled genomic DNA of all the six varieties was amplified with each ISSR primer with an average of four loci per primer. The size range of locus amplified by all the fifteen primers was ranging from 100 to 1200 bp depending upon on the ISSR primers. Only three out of fifteen primers, namely ISSR4, ISSR6 and ISSR8, were screened based on the number of amplified locus and size range from low to high. The selective ISSR primers distinguished all the six varieties of coffee with unique markers. ISSR 4 amplified two unique markers with a locus size 1300 bp and 950 bp for Sln.5B and 180 bp and 150 bp for Sln.13. ISSR6 had produced five varietal-specific markers with a locus size of 180 bp in Sln.5B, 1250 bp in Sln.11, 350 bp in Sln.3. ISSR8 had amplified seven unique loci across the coffee varieties with 700 bp and 800 bp in Sln.5B, 200 bp and 500 bp in Sln.11 and one locus each in Sln.7.3 and Sln.3 with 300 bp and 150 bp respectively. Repeated amplification of genomic DNA of all the six varieties of coffee with selective ISSR primers produced consistent ISSR genetic fingerprints. Selective ISSR primers were validated with marker parameters resolving power (RP), effective multiplex ratio (EMR), marker index (MI) and polymorphic information content (PIC). Utilisation of these markers in arabica coffee genetic improvement is discussed.