Use of Haploids in Species with Polysomic Inheritance
Polyhaploids derived from polyhaploids exhibiting polysomic inheritance may be homozygous or heterozygous. For instance, dihaploids of potato may be AA or Aa or aa, depending upon the genotype of the tetraploid potato, which can be heterozygous for this gene (AAAa, AAaa, Aaaa). Therefore, by doubling of haploids, homozygosity can not always be achieved in these cases, unless dihaploids are again used for production of monoploids. Therefore, the use of haploids in an autotetraploid crop like potato differs from that in crops like barley, rice wheat, etc.