The cytoplasm of Zea mays ssp. mexicana (teosinte) affects several inh
erited traits when combined with genotypes of maize (Zea mays ssp. may
s). The meiotic behavior and the total DNA content of four lines of ma
ize with teosinte cytoplasm were compared with those of the parental l
ines. The results obtained suggest that the cytoplasm of teosinte prom
otes an increase in total nuclear DNA content, perhaps through an incr
ease of highly repetitive DNA in the knob zones. The analysis of meiot
ic behavior indicates that the cytoplasm of teosinte can alter the spa
tial distribution of the genomes, since two groups of five bivalents e
ach were observed at a high frequency. During prophase I - anaphase I,
each group of five bivalents behaves in a slightly asynchronous way w
ith respect to the other group and, moreover, two nucleoli were observ
ed in 10% of the cells. These results suggest that the cytoplasm of te
osinte could induce changes affecting genomic structure and function i
n some maize genotypes. These changes are of potential importance for
breeding programs and evolutionary studies.