In 1982 Zea mays tetraploids (2n=40) were crossed in a greenhouse with the tetraploid hybrid Zea diploperennis x Z. perennis (2n=40) obtaining an annual and fertile hybrid with a chromosome number 2n=40.
F2 hybrid plants already mentioned have a great genetic variability, but in all cases are very prolific and fertile. From chromosomal study of the F2 it has been verified that all the descendants have a chromosome number of 2n=40, and the chromosomes match forming bi- or tetravalents, having practically no mono- or trivalents (Table 1). The average chiasma per cell is 36.94, the average pollen fertility in the population is 95% with a minimum of 93% and a maximum of 99%. In anaphase an equal chromosome number migrates to each pole and there are not any delayed chromosomes or inverted bridges.
From the F2 hybrid study between Z. mays, Z. diploperennis and Z. perennis it has been verified that, when the hybrid has a chromosome number of 2n=40, there is a high meiotic regularity and fertility in the hybrid and all its descendants.
Table 1: Meiotic configurations of F2 the tetraploid hybrid of Z. diploperennis x Z. perennis.
Maria del Carmen Molina
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