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|Title:||Tripsacum-X-Maize Hybrids in Tripsacum Cytoplasm|
|Author(s):||Porter, Hedera Lynn|
|Department / Program:||Agronomy|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||F$\sb1$ hybrids between tetraploid Tripsacum dactyloides (2n = 72) and diploid maize (2n = 20) were produced containing 82 chromosomes (72Td + 10Zm) in Tripsacum cytoplasm. Four backcrosses, with maize as the recurrent parent, produced an array of chromosomal types. The most common pathway for elimination of Tripsacum chromosomes was 2n = 82, 2n = 92, 2n = 56, 2n = 38, and 2n = 23 or 24 chromosomes. Plants with 2n = 38, 50, and 52 were also obtained.
Analysis of microsporogenesis showed no definitive evidence for intergenomic pairing. Averages for the chromosome configurations observed at diakinesis for the parents and hybrids were as follows: (1) T. dactyloides, 0.80I, 30.07II 0.15III, 2.65IV; (2) Z. mays, 0.12I 9.94II; (3) 2n = 82 F$\sb1$, 9.88I, 30.24II, 0.08III, 2.81IV, 0.02V; (4) 2n = 92 BC, 3.05I, 36.10II, 1.33III, 3.19IV; (5) 2n = 56 BC, 0.97I, 26.93II, 0.29IV; (6) 2n = 38 BC, 16.08I, 10.19II, 0.27III, 0.07IV, 0.02V; and (7) 2n = 28 BC, 24.83I, 0.82II, 0.37III, 0.24IV. Multivalent configurations in the 28- and 38-chromosome plants were mostly of an end-to-end type commonly observed in haploid plants.
Twenty-seven morphological characters were recorded for Tripsacum dactyloides, Zea mays, and the following hybrids: 2n = 82; 2n = 92; 2n = 56; 2n = 52; 2n = 38; and 2n = 28. Multivariate analysis (cluster analysis, discriminant analysis and principal components analysis) was used in order to consider many variables simultaneously.
Seeds with multiple embryos were found in all F$\sb1$ and backcross generations examined. The frequency of multiple embryos varied from 10.5% for the 82-chromosome F$\sb1$ to 44.4% for the 52-chromosome backcross hybrid. Multiple individuals produced by a single seed usually contained the same chromosome number.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1987.
|Date Available in IDEALS:||2014-12-16|