Determination of genetic diversity among wild and domesticated beans using Inter Simple Sequence Repeats(ISSRs),

Introduction Many different DNA-based molecular techniques are being developed for fingerprinting and to estimate genetic diversity in eukaryotic organisms. Because of ¿le relative ease in its utilization, PCR is increasingly being used as a tool in marker development. Random amplified polymorphic DNA (RAPD) markers are easier to analyze than RFLPs and are being used in breeding programs to tag genes controlling important agronomic traits; however, RAPDs have been shown to be less reproducible among laboratories (Jones et al., 1997). Amplified firagment length pol)miorphism (AFLP) markers are anotiier PCR-based method, which reveal a large number of reproducible markers distributed throughout the genome (Jones et al., 1997). Use of radioactive isotopes and fluorescent labeling as part of the AFLP technique is expensive and might not be affordable to many laboratories in developing countries. Microsatellites DNA sequences, or Simple Sequence Repeate (SSRs), are sequences of di-, trior tetaranucleotides repeated many times in the genome, which are very abundant in eukaryotic genomes. SSRs motifs can present high levels of allelic diversity at these loci, making them valuable as genetic markers (Panaud et al., 1995). SSRs can be analyzed using PCR but require primers specific to the flanking sequence of the SSR, a st^ that requires the use of genomic libraries, cloning and sequencing. Although very powerfiil for cultivar fingerprinting, development of microsatellites is therefore costly and lengtiiy.