Isozymatic and morphological diversity in the races of maize of Mexico

To determine the relationships and genetic diversity among the Mexican races of maize, 209 accessions representing 59 races were analyzed for 21 enzyme systems encoded by 37 loci; 154 out of the 209 accessions were grown in multiple locations and seasons irt Mexico and 47 morphological characters were measured. A very high level of variation among and within the Mexican races was found. However, more than 65% of the alleles Sound in the accessions studied are rare, occurring at frequencies below 0.01. In addition, some populations have low levels of genetic diversity and have values of genetic differentiation similar to selfing crops. Most of the accessions with low values of genetic diversity are specialty varieties.