Asparagus is especially suitable for polyploidy breeding. The aim is to develop clone-based hybrid varieties, in particular male 4x varieties. For this purpose, genetically divergent diploid idiotypes") are subjected to mitotic or meiotic polyploidization. In developing hybrid partners, special attention is paid to resistance in addition to yield and quality characters. Early diagnoses are apphed in selection so as to shorten breeding times. Somaclonal variations may occur relatively often on in vitro propagation; these need to be eliminated. Triplex and quadruplex type males are suitable for paternal hybrid partners. Strong inbreeding depressions need to be avoided in their production.
Isocnzyme analyses bave been carried out in polyploid rye. Taking into eonsideration zymograms at the diploid level, eonclu.sions ean be drawn eoncerning the geneties of band positions and band intensity. This IS rather clear with tbe aspartate aminotransferase and the NAD-specific aromatic aleohol debydrogenase. For both isoenzymes one gene locus witb two alleles is responsible in tbe zones analyzed. In both cases a superdominance is assumed. Thereby nulUplex-, simplex-, duplex-, triplex-and quadruplex types can be distinguished. For tbe banding pattern witb the leucine aminopeptidase two gene loci witb two alleles each are responsible. With allelic interaction codominance is supposed. On this base it is possible to differentiate between bomozygosity and heterozygosity. Difficulties in autopolyploid breeding can be overcome by means of geneticallyanalyzed isoenzymes as markers. This is demonstrated by examples.
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