Cytogenetic relationship of Zea mays ssp mays L., Zea mays ssp. mexicana, Zea diploperennis and Zea perennis
1994
dela Vina, A.C. | Ramirez, D.A. | Engle, L.M. | Mendoza, A.C.A. (Philippines Univ. Los Banos, College, Laguna (Philippines). Inst. of of Plant Breeding)
Hybrids between eight genotypes of maize Zea mays ssp. mays and its three wild relatives (Z. mays ssp mexicana, Z. diploperehis and Z. perennis) were produced. Thirty eight cross combinations were made. Cytological studies showed that three species (Z. mays ssp mays, Z. mays ssp mexicana and Z. diploperennis) are diploids with chromosome number of 2n=20. On the other hand, Z. perennis is tetraploid with 2n=40 chromosomes. F1 and BC1 hybrids between the diploid species have 2n=20 chromosomes while the Z. mays ssp mays x Z. perennis F1 hybrid has 2n=30 chromosomes and the BC1 has 2n=22 chromosomes. Meiotic behavior was generally normal in the diploid species and their hybrids. Low frequencies of meiotic aberrations such as Laggards, bridges and early disjunction were observed. Furthermore, the meiotic aberrations of the hybrids between ssp mays and ssp mexicana are much lower than that of ssp mays x Z. diploperennis hybrids. Pollen fertility of the F1 and BC1 hybrids are high, ranging from 78.0 percent to 93.6 percent. In the Z. mays ssp mays x Z. perennis F1 ad BC1 hybrids, the observation is that there is wider range of meiotic aberrations and at a higher frequencies than that of the hybrids between diploid species. Consequently, pollen fertility was very low (36.88 percent to 77.09 percent). Pathways of genetic transfer from the wild relatives to maize are proposed
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