Nature, Evolution, and Breeding of Polyploids
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1984-05
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Abstract
Different kinds of polyploids are defined andcharacterized by their genome formulas. It is emphasized that natural polyploids range-in genome composition from true autopolyploids to true allopolyploids. The origin and evolution of polyploids is discussed, and special attention is paid to the role of numerically unreduced or 2n gametes. Methods of inducing autopolyploidy are mentioned along with the requirements that diploid crops should meet in order to obtain useful results from somatic doubling. Methods of resynthesizing existing allopolyploid crops or synthesizing new ones are evaluated and the main requirements for success discussed. It is emphasized that genetically broad initial material is indispensable both for induction of autopolyploids and for (re)synthesis of allopolyploids that are to be useful for breeding. Some characteristic features relevant to the breeding of autopolyploids are described with emphasis on the effects of di-allelism and multi-allelism on inbreeding depression and heterosis. Also some particular characteristics of allopolyploids are treated, and some unconventional breeding approaches are briefly discussed. Index Descriptors: polyploidy, evolution, breeding, somatic doubling, 2n gametes, multi-allelism, heterosis, and inbreeding depression.
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Iowa State Journal of Research, May 1984, Vol.58 No.4