ASSESSMENT OF GENETIC DIVERSITY IN DENT AND POPCORN (ZEA-MAYS L) INBRED LINES USING INTER-SIMPLE SEQUENCE REPEAT (ISSR) AMPLIFICATION

Popcorn (Zea Mays L.) hybrids grown in the United States are derived f rom narrow-based germplasm, and standard RFLP analysis detects relativ ely little polymorphism. Inter-simple sequence repeat (ISSR) amplifica tion, a novel technique based on PCR amplification of inter-microsatel lite sequences to target multiple loci in the genome, was employed to investigate its potential for detection of polymorphism among nineteen popcorn and eight dent corn inbred lines. ISSR yielded an average of 54 bands/primer/inbred line, with over 98% of the bands repeatable acr oss DNA extractions and separate PCR runs. Ten primers based on di- an d tri-nucleotide tandem repeats revealed 73% and 87% polymorphism amon g popcorn and dent corn lines, respectively, with an overall 95% polym orphism rate. Principal component and cluster analyses resulted in gro uping of dent and popcorn lines corresponding to their heterotic breed ing pools. ISSR amplification, in addition to being both simple and co st and time efficient, provides for rapid production of highly polymor phic markers which appear to correspond to known pedigree information. Therefore, the ISSR technique may have great potential for identifyin g polymorphism in species with narrow-based germplasm, and for use in DNA marker-assisted breeding approaches.