K.J. Kasha, Y.S. Shim, E. Simion, J. Letarte
In the applications of haploid plants, chromosome doubling has a major role and has been widely researched. Chromosome doubling restores fertility to plants and often results in genetically homozygous doubled haploids. In diploid and allopolyploid species these homozygous plants have the potential to become pure breeding new cultivars or the parents for producing uniform hybrids. It is also significantly easier to select for disease, agronomic and quality traits on doubled haploid lines than on F2 plants. With autopolyploid species it is easier to breed and select at the haploid level. However, chromosome doubling to the optimum ploidy level is desired for maximum yield. Chromosome doubling procedures are dictated to some extent by the methods used to produce the haploid plants. If the haploid plant is derived from the male gamete (androgenesis) it is often feasible to apply doubling treatments at the single uninucleate stage or at the first post-meiotic mitotic division (PMI). What was initially described as spontaneous doubling may actually result from the type of pretreatments used to induce embryogenesis. More recently, the use of anti-microtubule agents for induction of both embryogenesis and chromosome doubling from microspores are leading to improved doubling frequencies. Evidence suggests that much of the microspore stage doubling could arise through nuclear fusion. The female gamete is protected by the ovule, making it more difficult to study and apply treatments for chromosome doubling. These gynogenetic haploids most often have come from ovule culture or chromosome elimination and the haploid seedlings are often the stage available for treatment to double the chromosomes.
Kasha, K.J., Shim, Y.S., Simion, E. and Letarte, J. (2006). HAPLOID PRODUCTION AND CHROMOSOME DOUBLING. Acta Hortic. 725, 817-828
DOI: 10.17660/ActaHortic.2006.725.114
androgenesis, gynogenesis, chromosome elimination, nuclear fusion, endomitosis, anti-microtubule agents, pretreatments

Acta Horticulturae