Cytogenetic relationship of Zea mays ssp. mays (L.) and Zea perennis (Hitch) Reeves and Mangelsdorf
1994
Dela Vina, A.C. | Ramirez, D.A. (Philippines Univ. Los Banos, College, Laguna 4031 (Philippines). Inst. of Plant Breeding)
Cytological analysis revealed that the Zea mays ssp mays is a true diploid maize with a chromosome number equal to 2n = 20, while Zea perennis is a perennial tetraploid with chromosome number 2n = 40. The F1 hybrid is a triploid with a chromosome number equal to 2n = 30, one set of chromosome coming from the maize parent and two sets from the perennial parent. The backcross (BC1) has 2n = 20-25 indicating perennis chromosome elimination. Bivalent formation predominated in the parents while a wide range of chromosomal association was noted in the hybrids. High frequency of normal cells was observed in meiosis 1 and meiosis 2 in maize while chromosomal abnormalities such as laggard, early disjunction, bridge and bridge and fragments at relatively high frequency were noted in perennis, F1, and BC1. The pollen fertility of the hybrids and perennis was relatively low (36.88-77.09 percent) compared to maize (97.43 percent). Analysis of pachytene chromosomes revealed differences among the parents and the hybrids in terms of relative length, position of the centromere and the presence or absence of knobs
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