Microsatellite and RAPD polymorphisms in Ontario corn hybrids are related to the commercial sources and maturity ratings

Random-amplified polymorphic DNA (RAPD) and microsatellite markers were use d to estimate the genetic relationships among 37 Ontario corn hybrids. Almo st all (95%) of the 160 RAPD fragments and all of the 79 microsatellite all eles were polymorphic across the 37 hybrids. Similarity values among the hy brids ranged from 31% to 86% when based on the RAPD data. The similarities based on microsatellite markers ranged from 12% to 77%. The genetic diversi ty revealed by microsatellite marker analysis was higher than that obtained fro RAPD analysis. The similarity matrices for the microsatellite data and the RAPD data were moderately correlated (0.43). Cluster analyses based on either type of marker showed that most oaf the hybrids from the same compa ny were closely related to each other. Both dendrograms clustered similar p airs or groups of hybrids. A principal component analysis, based on the com bined RAPD and microsatellite data, yielded a good separation of the hybrid s with Ontario Corn Heat Unit (OCHU) values <2800 from those with OCHU valu es >2800. Seventeen RAPD markers and 5 microsatellite markers were signific antly associated with the OCHU ratings of the hybrids.