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TRUE‐BREEDING COLCHICINE‐INDUCED MUTANTS FROM SORGHUM HYBRIDS
Author(s) -
Franzke Clifford J.,
Sanders Mary E.
Publication year - 1965
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1965.tb06778.x
Subject(s) - biology , hybrid , pollen , polyploid , colchicine , mutant , ploidy , genetics , allele , sorghum , chromosome , botany , plant breeding , gene , agronomy
Colchicine treatment of sorghum seedlings of both F 1 hybrids and of their pollen parent lines resulted in complex mutant plants the majority of which were true‐breeding. Recessive irradiation‐induced characters originally homozygous in the pollen parent lines and heterozygous in the hybrids did not appear in any of the mutants or their self progenies. Recessive normal characters apparently absent in the pollen parent lines and heterozygous in the hybrids appeared in some mutants and bred true in their self progenies. These results are consistent with the hypothesis that colchicine‐induced mutants arise through chromosome substitution (Sanders and Franzke, 1964, Jour. Arnold Arb. 45: 36). Since sorghums with 2 n = 20 are believed to be of polyploid derivation, interchangeable chromosomes carrying different alleles could be present in true‐breeding lines. There is evidence that diploid mutant complements may result from reduction of polyploid nuclei. Since the proportion of true‐breeding mutants was as large from the highly heterozygous seedlings as from the homozygous seedlings, segregation of chromosomes during reduction must be primarily by c‐pairs which later separate as the homologues of a new cell. Plants from such cells would be equivalent to doubled haploids. With colchicine treatment, true‐breeding lines have been obtained from multiple hybrids in a single step rather than after many generations of selling.