True-breeding lines are required for the development and production of crop varieties. In a classical breeding approach these lines are obtained through inbreeding, and often 7-9 generations of inbreeding is performed to achieve the desired level of homozygosity, over a period of several years. In contrast, the chromosomes of haploids can be doubled to produce true-breeding lines in a single ge...

Factors affecting reliable plant regeneration from unfertilized ovule culture of gentians (Gentiana spp.) were examined. Cold pretreatment (4°C) of flower buds enhanced or maintained production of embryo-like structure (ELS). When 43 genotypes were surveyed in two different labs, 40 of them produced ELSs ranging from 0.01 to 26.5 ELSs per flower bud. No ELSs could be obtained in three genotypes...

Using the Saccharomyces cerevisiae MATa/MATalpha ORF deletion collection, homozygous deletion strains were identified that undergo mating with MATa or MATalpha haploids. Seven homozygous deletions were identified that confer enhanced mating. Three of these, lacking CTF8, CTF18, and DCC1, mate at a low frequency with either MATa or MATalpha haploids. The products of these genes form a complex in...

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...