The nutrient limitation hypothesis provides a nongenetic explanation for the evolution of life cycles that retain both haploid and diploid phases: differences in nutrient requirements and uptake allow haploids to override the potential genetic advantages provided by diploidy under certain nutrient limiting conditions. The relative fitness of an isogenic series of haploid, diploid and tetraploid...

333 converted into homozygous parental breeding lines, as desirable allele combinations are lost through recombination during meiosis. That obstacle has been overcome by Wijnker et al. who have reverse bred Arabidopsis thaliana parental lines from heterozygous hybrids using a process that involves preventing meiotic crossing over. The authors used RNA interference (RNAi) to silence DISRUPTED ME...

haploid inducer line can be transferred (DH) technology can not only shorten the breeding process but also increase genetic gain. Haploid induction and subsequent genome doubling are the two main steps required for DH technology. Haploids have been generated through the culture of immature male and female gametophytes, and through inter- and intraspecific via chromosome elimination. Here, we fo...

On the basis of the first inducer of maternal haploids in maize (Zea mays L.), Stock 6 (Coe, 1959), a number of new inducer lines have been created (Tyrnov et al, 1984; Lasharmes et al, 1988; Sarkar et al, 1994; Shatskaya et al, 1994; Chalyk, 1999; Rober et al, 2005). The inducers possess dominant anthocyanin marker genes allowing haploids to be identified at different stages (dry seeds, seedli...

Abstract Diverse processes leading to doubled haploid (DH) plant production, such as microspore embryogenesis, gynogenesis, and distant hybridization followed by genome elimination, are based on the unique ability of cells form embryos without fertilization. All these possible because various in vitro culture systems that enable growth development tissues or single outside parental organism. Th...

The creation of homozygous plants is essential for both genetic studies and the production hybrid seeds, particularly in that were pollinated by an alien species. Dihaploid (DH) technology important application obtaining lines used to plant speed breeding programs. generation haploid embryos pollen irradiation pollination female flowers with irradiated has been successfully applied. influence o...

The great economic importance of sugar beet determines the ongoing biotechnological studies conducted worldwide to improve technology obtaining doubled haploids (DHs) using method unpollinated ovule culture in vitro. To induction gynogenesis, we tested effect thidiazuron (TDZ), temperature bud pretreatment, different concentrations sucrose, and culturing on liquid or solid medium. Three genotyp...

suns. The extension of the Andromeda nebula beyond the photographic limits is presumably typical of what may be found for other such objects. Comparisons with the surface brightness of the galaxy are still hampered by uncertainties in the data for our own system. There may be no part of the galaxy which, seen from outside, would be as bright as the central portion of M 31. In the latter system ...

H A P L O I D vertebrates may occur spontaneously but are very rare (Fankhauser, 1941; Humphrey & Fankhauser, 1957); however, haploids may be experimentally produced in fish (Swarup, 1959) and in mammals (Beatty, 1953), while amphibian eggs may be so treated that all developing embryos are haploid (Porter, 1939; Gurdon, 1960). The full descriptions of the development of haploid Rana pipiens (Po...

We tested the hypothesis that the time course of the evolution of antifungal drug resistance depends on the ploidy of the fungus. The experiments were designed to measure the initial response to the selection imposed by the antifungal drug fluconazole up to and including the fixation of the first resistance mutation in populations of Saccharomyces cerevisiae. Under conditions of low drug concen...