GENETIC STUDIES ON THE BEHAVIOR OF THE B$sup 3$ CHROMOSOME IN TB-3a, AND THE USE OF A-B TRANSLOCATIONS IN MUTATION STUDIES, IN MAIZE
An A-B translocation, designated as TB-3a, was used to study the behavior of the B/sup 3/ chromosome. Through a detafled genetic study of progenies produced by the cross 3 3 x 3 3/sup B/ B/sup 3/ B/sup 3/ (pollen parent), the nondisjunction of B/sup chromosomes during microsporogenesis and at the 2nd mitotic division in microspore was confirmed. However, nondisjunction of the B/sup 3/ chromosomes at the 2nd microspore division was found only 3/sup B/ B/ sup 3/ pollen, not in 3 B/sup 3/ pollen. Rates of nondisjunction of the B/sup 3/ chromosomes in 3/sup 3/ B/sup 3/ pollen were similar in the three families analyzed but rates of preferential fertilization varied greatiy in the different families. When 3 3/sup B/ B/sup 3/ B/sup 3/ plants were used as egg parents, nondisjunction of the B/sup 3/ chromosomes at meiosis was apparent. There was no indication of nondisjunction during embryo sac formation. The advantages expected from the use of A-B translocations in the study of mutations as compared with conventional methods are discussed. To test the expected advantages, TB-1a, TB-3a, TB-9a, TB-9b, and TB-10a were chosen as pollen parents. As egg parents, Hy2/Oh7, multiple-dominant single-cross hybrids, McClintock's Ds;ac/ac and Ds;Ac/ ac, bz-s and bz-m, and wx-s and wx-m were used. The first two kinds of egg parents were studied with and without x-ray treatment. The use of mutable strains was based on the expectation that mutation would be enhanced by the transposition of mutable elements. The total number of kernels analyzed was approximately 648,000. The most frequent phenotypes expressed as seedling and endosperm mutants were yellow-green and abnormal morphology, and defective kernels, and endosperm marking, respectively. Relatively few cases of prospective mutants transmitted their mutant phenotypes to the following generations, and only rarely were the mutant phenotypes fixed in homozygous condition after one or two generations of self-pollination. In general no qualitative differences were observed in seedling and endosperm mutants among the different pollen parents, egg parents, or egg parent treatments. The results indicate that the use of A-B translocations in mutation study does not appear to be promising. The technical difficulties encountered in the experiments are also discussed. (Dissertation Abstr., 24: No. 9, March 1964)
- Research Organization:
- Originating Research Org. not identified
- NSA Number:
- NSA-18-019513
- OSTI ID:
- 4020621
- Resource Relation:
- Other Information: Thesis. Orig. Receipt Date: 31-DEC-64
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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