AFLP-based genetic relationships among maize inbred lines selected in a climatically temperate location

AFLP analysis was performed on a series of 71 Italian inbred lines, conside red representative of the breeding material maintained at the Bergamo Maize Station of the Istituto Sperimentale per la Cerealicoltura. Twenty America n reference lines, distinctive for the major heterotic groups available sup plied the basis of genetic diversity to which the Italian inbreds were corr elated in the assessment of their relative genetic relationships. A total o f 682 poly morphic fragments were identified, which were used to calculate pairwise genetic distances and to subsequently derive hierarchical clusteri ng. Clustering of the inbreds reflected pedigree information and resulted i n the identification of major groups derived from Lancaster Sure Crop (LSC) and Iowa Stiff Stock Synthetic (BSSS) heterotic breeding material. AMOVA s tatistics, performed on the established genetic structure, revealed a high proportion of variance within heterotic groups, indicating that in the bree ding program variability had been maintained within the groups during inbre d line constitution. AMOVA results were corroborated by diversity analysis, which revealed a high level of genetic variability within and across heter otic groups. In conclusion, AFLPs appeared highly informative and constitut ed a valuable tool for assigning inbred lines to, and assaying genetic vari ability across, heterotic groups.