• Genomics & Informatics
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• v.6 no.3
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• pp.130-135
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• 2008

The haplotypes of a 200 kb region in the human chromosome X terminal band (q28) were analyzed using the International HapMap Project Phasell data, which had been collected for three analysis panels (YRI, CEU, and CHB＋JPT). When multiple linkage disequilibrium blocks were encountered for a panel, the neighboring haplotypes that had crossover rate of 5% or more in the panel were combined to generate 'haploid' configurations. This resulted in 8, 7, and 5 'haploid' configurations for the panels of YRI, CEU, and CHB＋JPT, respectively. The multiple sequence alignment of these 'haploids' was used for the calculation of allele-sharing distances and the subsequent principal coordinate analysis. Two 'haploids' in CEU and CHB＋JPT were hypothesized as 'parental' in light of the observations that the successive recombinants of these haploids can model two other haploids in CEU and CHB＋JPT, and that their configurations were consistent with those in YRI. This study demonstrates the utility of haplotype phylogeny in understanding population evolution.

• Current Research on Agriculture and Life Sciences
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• v.31 no.2
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• pp.75-82
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• 2013

Haploids are plants with a gametophytic number of chromosomes in their sporophytes. Androgenesis occurs from asymmetric division of pollen grains into generative cells and vegetative cells, followed by re-entry of the vegetative cell during S-phase, which causes microspores progress into G2/M transition in culture. One of the most interesting features of haploids is the possibility to produce doubled haploid (DH) individuals. Doubled haploidy is extremely useful to plant breeders because it enables shortened breeding periods and efficiency in selection of useful recessive agronomic traits. Doubled-haploid technology is not only applicable to breeding, but also to transformation programs of desired genes. In addition to practical breeding programs, DH lines provide useful materials of fundamental genetics including exploitation of QTLs and genes conferred with various agronomic traits by establishing DH populations. This paper provides historical overviews on androgenesis and describes several mechanisms associated with pollen embryogenesis, including mode of actions in pollen embryogenesis, mechanisms of chromosome doubling and factors affecting androgenesis. We also discuss recent progress in application of haploids to breeding, genes associated with in vitro response and drawbacks to anther culture for application of doubled haploids in crop breeding.

• Journal of the Korean Society of Tobacco Science
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• v.4 no.2
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• pp.23-30
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• 1982

Six flue- cured cultivars of Nicotiana tabacum L., 15 possible $F_1$ hybrids and $F_2$ Populations among them, and 15 haploid Populations from Fl hybrids and haploids from Parents, were evaluated. Comparisons of the $F_1$, hybrids and $F_2$ Populations with the Parents indicated that heterosis values were small but significant for yield, plant height, days to flower, leaf length and width and total alkaloids from-6.0% to 5.4% in $F_1$ hybrids, and from -3.4% to 3.6% for Plant height days to flower leaves per plant in $F_2$ populations, respectively. There were positive correlations for yield, plant height, days to flower, leaves per plant and total alkaloids between diploid and haploid populations. Increase or decrease ratio of haploids to diploids of total alkaloids was appeared to 30.3%. Those for yield, leaf length and width, value arid reducing sugar were ranged from -4.1% to -27.6%.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.22 no.1
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• pp.41-44
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• 1977

Production of haploids in vitro anther culture of Nicotiana tabacum L. was oriented in a large number on a chemically defined culture medium. The haploids were screened for T.M.V. resistance and the segregating ratio in F$_1$ were in good agreement with the expected ratio.

• Journal of the Korean Society of Tobacco Science
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• v.16 no.1
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• pp.64-68
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• 1994

The present experiments were conducted to investigate some of the factors affecting the number of haploids derived from anther culture of Nicotiana tabacum. Anther - donor plants grown under controlled environment room at 3$0^{\circ}C$ yielded more haploid than room at 18, 25 and 26-22-18$^{\circ}C$ in anther culture. Donor plants starved of fertilizer yielded more haploids as compared to those of the well fed with fertilizer in anther culture. Pretreatment of exercised flower bud at 5$^{\circ}C$ was shown to be more effective in anther culture than pretreatment at 7 and 1$0^{\circ}C$, and the optimum temperature and period of pretreatment were 4 or 6 days at 5$^{\circ}C$.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.29 no.4
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• pp.328-333
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• 1984

Variation in ploidy level of regenerated plants from rice anthers and effective diploidization methods of haploid plants were studied to obtain basic information in rice breeding through anther culture. In a total of 574 plants derived from anther culture using 14F$_1$ hybrids as materials, there were 49.7% haploids, 48.6% diploids and 1.7% polyploids, respectively. The frequency of haploids in Japonica/Indica crosses was 60.6%, and that of Japonica/Japonica crosses was 43.0% in average. Inclusion of 2.4-D or NAA as phytohormone may increase the frequency of haploids, but kinetin may increase the frequency of diploids. The rate of auto-diploidization by tiller separation of haploid plants showed 8.2% in average. The rate of diploidization by leaf-sheath injection of colchicine showed 18.8% in average. Morphological characters of haploids plants showed that 64.6% in culm length, 63.4% in panicle length, 68% in flag leaf length, and 74.4% in flag leaf width compared to diploid plants. These apparent morphological differences will contribute to identify the ploidy of plants derived from rice anther culture.

• Journal of Plant Biotechnology
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• v.39 no.1
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• pp.13-22
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• 2012

Plant regeneration has been optimized increasingly by organogenesis and somatic embryogenesis using a range of explants with tissue culture improvements focusing on factors, such as the age of the explant, genotype, media supplements and $Agrobacterium$ co-cultivation. The production of haploids and doubled haploids using microspores has accelerated the production of homozygous lines in Brassicaceae crop plants. Somatic cell fusion has facilitated the development of interspecific and intergeneric hybrids in sexually incompatible species of $Brassica$. Crop improvement using somaclonal variation has also been achieved. Transformation technologies are being exploited routinely to elucidate the gene function and contribute to the development of novel enhanced crops. The $Agrobacterium$-mediated transformation is the most widely used approach for the introduction of transgenes into Brassicaceae, and $in$ $vitro$ regeneration is a key factor in developing an efficient transformation method in plants. Although many other Brassicaceae are used as model species for improving plant regeneration and transformation systems, this paper focuses on the recent technologies used to regenerate the most important Brassicaceae crop plants.

• Korean Journal of Plant Resources
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• v.23 no.6
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• pp.503-512
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• 2010

Anther derived double haploids (DHs) from sweet pepper genotypes ('Special', 'Derby', 'Bossanova', 'Fiesta', 'Debora' and 'Minipaprika') were used to study the agronomic variation in 2006. Ninety-nine successful DHs regenerants (32 from 'Special', 25 from 'Derby', 23 from 'Bossanova', 10 from 'Fiesta', 6 from 'Debora' and 3 from 'Minipaprika') were transplanted at plastic house and studied on their agronomic characters. Variation in agronomic characters was observed within the DHs of each genotype. DHs obtained from 'Derby' and 'Fiesta' exhibited wide variation in fruit yield $plant^{-1}$ whereas averaged fruit yield $plant^{-1}$ was highest in 'Derby' (1608 g) and less variation was observed in DHs of 'Bossanova'. Based on the agronomic characters expressed in DHs population at this environment, SP55, SP56, SP60, and SP116 from 'Special', SP8, SP10, SP14, SP16, and SP34 from 'Derby', SP115, SP119, SP142, SP143, SP196, and SP199 from 'Bossanova', SP41, SP45, and SP114 from 'Fiesta', SP21 from 'Debora' and SP91 from 'Minipaprika' identified as elite inbred lines and these DH lines could be used for commercial hybrids production in sweet pepper. Genetic relationship among the selected inbred lines using molecular markers and their response to diseases are further recommended to study.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.1
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• pp.62-67
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• 2002

An efficient system of rice microspore culture could contribute to the production of genetically modified rice. The microspores were isolated by mechanical or shed methods. The number of microspores per 100 anthers isolated at uninucleate stage was higher than (or similar to) those at binucleate stage in isolation method with pestle or spatular, but microspore divisions were not easily observed on both stages. On the other hand, pollen division in shed pollen culture was observed more frequently at uninuclear than at binuclear stage. Cold pretreatment at 1$0^{\circ}C$ for 10 days resulted in the best multicellular division to produce microcalli at 12.5% efficiency in shed microspores. Heat shock at 33$^{\circ}C$ for one hour before or after pollen shedding enhanced cell division and callus formation. Out of twelve green regenerants, two were haploids and ten were diploids based on the chromosome analysis of root tips. The size of stoma was 12$^{m}$ m in haploids and 15 ${\mu}{\textrm}{m}$ in diploids determined by scanning electron microscope (SEM).

• Journal of Plant Biotechnology
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• v.5 no.1
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• pp.51-57
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• 2003

Doubled haploids have long been recognized as a valuable tool in plant breeding since it not only offers the quickest method of advancing heterozygous breeding lines to homozygosity, but also increased the selection efficiency over conventional procedures due to better discrimination between genotypes within any one generation. Salt tolerant mutants were obtained in rice the variety, 'Hawsungbyeo', through in vitro mutagenesis of in vitro cultured anther-derived calli. Various doses (30, 50, 70 and 90 Gy) of gamma ray were applied to investigate the effect of radiation on callus formation on medium containing 1% NaCl, green plant regeneration, frequency of selected doubled haploid mutants and of the salt tolerant screen. It was demonstrated that the dose of 30 and 50 Gy gamma rays had significant effects on callus formation, regeneration and selection of salt tolerance. No tolerant lines were obtained from non-mutagenized cultures. From gamma ray irradiated cultures, five tolerant lines ($M_2$generation) at germination stage and 13 tolerant lines ($M_3$genoration) at seedling stage were obtained. The frequency of salt tolerant mutants indicates that anther culture applied in connection with gamma rays is an effective way to improve salt tolerance.