APOMICTICALLY REPRODUCING 39-CHROMOSOME MAIZE-TRIPSACUM HYBRIDS

Creation of 39-chromosome hybrids of maize with Tripsacum (30Mz + 9Tr) continuously reproducing by apomixis Is reported. The studied lines w ere discovered in the progeny of 56-chromosome F-1 hybrid (20Mz + 36Tr ) and had different origins. Cytogenetic analysis and the absence of m olecular (at the DNA level) and isozyme polymorphism in the progeny of 39-chromosome hybrids confirmed stability of apomictic reproduction. Based on karyological data and analysis of PCR products, the conclusio n was drawn that, despite the different origins of occurrence, both st udied hybrids have identical sets of 9 Tripsacum chromosomes. The resu lts are discussed with regard to Tripsacum genome structure, perspecti ves in utilizing the obtained lines to localize and map apomixis-deter mining genes, and the creation of hybrid corn with fixed heterosis.