• 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).

• Korean Journal of Breeding Science
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• v.42 no.5
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• pp.431-438
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• 2010

Anthers of sweet pepper $F_1$ cultivar 'Special' were cultured on Dumas De Vaulx (C medium), supplemented with $0.1mgL^{-1}$ 2, 4-D and $0.1mg{\cdot}L^{-1}$ kinetin with 3% sucrose, and 0.32% phytagel. The calluses obtained were further sub-cultured on Murashige and Skoog (MS) medium without growth regulators for regeneration. Regenerated plantlets were grown in plastic pots under plastic house and characterized their cytological and morphological characters in spring, 2008. Twenty percent plantlets were identified as haploid plants after chromosome and ploidy analysis. Haploid plants contained 12 chromosomes, high stomatal density with small stomatal length as compared to diploid plants. Stomatal length in haploids was 23.3% smaller than diploids. Haploid plants were characterized as small leaf and petiole size, poor vigor, thin stem and short plant height, short internodes and small flower buds, fruit size and fruit weight as compared to diploid plants and most of the haploid fruits were seedless. SP55, SP62, SP68, SP72 and SP77 are found high yielding double haploids with high total soluble content (8.6, 8.7, 9.2, 9.1 and $9.8^{\circ}Brix$, respectively) and desirable fruit shape, and recommended them to exploit as inbred lines for heterosis breeding.

• Journal of The Korean Society of Grassland and Forage Science
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• v.17 no.1
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• pp.1-10
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• 1997

Unreduced (2n) gametes are meiotic products (pollen or egg) having a sporophytic (somatic) chromosome number, resulting from abnormalities during either microsporogenesis or megasporogenesis. They occur naturally at a low frequency in many plant species. Unreduced (2n) gametes in plants can be identified for four possible ways as follow i) pollen size and/or shape differences between haploid (n) and diploid (2n) pollen, ii) ploidy analysis (chromosome number) of progeny or meiotic analysis (presence of dyads andlor triads at the microspore stage), iii) progeny performance and fertility and iv) dosage of isozyme and DNA markers. Unreduced (2n) gametes can be an effective breeding tool in synthesizing new cultivars, providing a unique method to maximizing heterozygosity, i.e., transferring a large proportion of the non-additive genetic effects (intra- and inter- locus interactions) h m parent to offspring and can also be used to overcome infertility of interploidy crosses. Sexual polyploidization through 2n gametes has been a major route to the formation of naturally occurring polyploids. The three mechanisms of 2n pollen formation in potato have been discovered as follow: i) parallel spindles (ps) or tripolar spindles (ts), ii) premature cytokinesis (pc-I, pc-2) and iii) synaptic mutants (sy-2, sy-3, sy-4). Genetic analysis indicated that the mechanisms of 2n gamete formation were controlled by single recessive gene in potato, alfalfa, red clover, etc., and by two recessive genes in wheat. The use of 2n gametes which can efficiently transfer germplasm fiom wild relatives to cultivated species, especially fiom diploid to tetraploid could make a contribution to the improvement of germplasm base in breeding programs.

• Horticultural Science & Technology
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• v.33 no.6
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• pp.869-876
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• 2015

Wild relative species of domesticated crops are useful genetic resources for improving agronomic traits. Cytogenetic investigations based on chromosome composition provide insight into basic genetic and genomic characteristics of a species that can be exploited in a breeding program. Here, we used FISH analysis to characterize the ploidy level, chromosome constitution, and genomic distribution o f 5S and 4 5S r ibosomal DNA (rDNA) in four wild Cucurbitaceae species, namely, Citrullus lanatus (Thunb.) Mansf. var. citroides L. H. Bailey (2n = 22), Melothria japonica Maxim. (2n = 22), Sicyos angulatus L. (2n = 24), and Trichosanthes kirilowii Maxim. (2n = 66, 88, 110 cytotypes), collected in different areas of Korea. All species were diploids, except for T. kirilowii, which included hexa-, octa-, and decaploid cytotypes (2n = 6x = 66, 8x = 88, and 10x = 110). All species have small metaphase chromosomes in the range of $2-5{\mu}m$. The 45S rDNA signals were localized distally compared to the 5S rDNA. C. lanatus var. citroides and M. japonica showed one and two loci of 45S and 5S rDNA, respectively, with co-localization of rDNA signals in one M. japonica chromosome. S. angulatus showed two co-localized signals of 5S and 45S rDNA loci. The hexaploid T. kirilowii cytotype showed five signals each for 45S and 5S rDNA, with three being co-localized. This is the first report of hexaploid and decaploid cytotypes in T. kirilowii. These results will be useful in future Cucurbitaceae breeding programs.

• Journal of Aquaculture
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• v.3 no.2
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• pp.135-144
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• 1990

Fertilized eggs of Oreochromis niloticus were subjected to cold treatments at $14^{\circ}C$ for 30, 45 and 60 minutes starting 5 minutes after insemination at $27^{\circ}C$. Ploidy levels were determined by chromosome preparations and the analysis of both cell and nuclear sizes. A temperature shock of $14^{\circ}C$ for 60 minutes yielded the best results ( $83.3\%$). Gonadal development in both sexes was severely retarded in all triploid groups at 6 months of age.

• Journal of Embryo Transfer
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• v.17 no.1
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• pp.13-21
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• 2002

Intracytoplasmic Sperm Injection (ICSI) has been widely used fur both human infertility and basic research. However, the high incidence of chromosomal abnormality is severe problem in cattle. Various oocyte activation stimuli, therefore, were compared by assessment of developmental capacity and chromosome analysis. Motile sperm selected by Percoll-density gradient were treated with 5 mM dithiothreitol (DTT) and injected into an oocyte matured fur 24 h. Eggs were then allocated into 5 treatment groups. Group 1 (control), sperm injection was performed without any further activation stimuli to the oocytes. Group 2 (handled control), sham injection was performed without sperm. In Group 3, oocytes exposed to 5 (M ionomycin for 5 min at 39(C. Group 4. ionomycine + 1.9 mM demethylaminopurine (DMAP, 3 h) and Group 5, ionomycine + 3 h culture in Ml99 + DMAP. Cleavage and the later development rate in Groups 1, 2 and 3 were significantly (P<0.05) lower than those in Groups 4 and 5. The incidence of chromosomal abnormality in the embryos treated directly with DMAP after ionomycine was relatively higher than in the embryo of Group 3 h, delayed DMAP treatment. From this results DMAP caused to be arrested the release of the 2nd polar body, resulting in changes of chromosomal pattern. Therefore, the time interval between ionomycin and DMAP is a crucial role in bovine ICSI.

• Journal of Plant Biotechnology
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• v.31 no.1
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• pp.73-78
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• 2004

This study was carried out to develop an in vitro chromosome doubling systems for the breeding of tetraploid lily cultivar. Different concentration (ppm) and treatment time (hour) of colchicine, oryzalin and caffeine were compared for the efficiency of bulb regeneration and tetraploidization. The occurrence of tetraploid plants by colchicine was the highest in the concentration of 1,000 ppm for three hours. In oryzalin treatment, the best combination was at 30 ppm for three hours. However, the effects of oryzalin treatments were similar between 10 ppm and 30 ppm concentrations. The survival rate was dramatically reduced in a high concentration of caffeine although some treatments had a higher tetraploid induction. As a consequence, reliable results for the tetraploid production were obtained in the treatments of 1,000 ppm colchicine, 3,000 ppm oryzalin both for three hours, and 9,000 ppm caffeine for nine hours.

• Development and Reproduction
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• v.20 no.4
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• pp.305-314
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• 2016

The marine medaka, Oryzias dancena is a suitable sample as a laboratory animal because it has a small size and clearly distinguishes between female and male. Data on the growth and maturity of the diploid and triploid sea cucurbit species suitable for laboratory animals are very useful for studying other species. Triploidy was induced in the marine medaka by cold shock treatment ($0^{\circ}C$) of fertilized eggs for 45 min, applied two minutes after fertilization. The diploid and triploid male fish were larger than their female counterparts (P<0.05), and the concentrations of thyroid stimulating hormone (TSH) and thyroxine (T4) were higher in the induced triploids over 1 year (P<0.05). In both the diploid and tri-ploid groups the concentrations of TSH and T4 were higher in the male fish than in the females (P<0.05), while the testo-sterone and estradiol-$17{\beta}$ concentrations in the induced triploids were lower than in the diploids (P<0.05). The gonadosomatic index (GSI) of the triploid fish was lower than that for the diploids, and the GSI for females in each ploidy group were higher than that for the males. For both groups the GSI was highest at 4 months of age, and decreased thereafter to 12 months. Analysis of the gonads of one-year-old triploid fish suggested that the induction of triploidy probably causes sterility in this species; this effect was more apparent in females than in males.

• Plant Biotechnology Reports
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• v.5 no.3
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• pp.265-271
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• 2011

The cultivated potato as well as its tuber-bearing relatives are considered model plants for cell and tissue culture, and therefore for exploiting the genetic variation induced by in vitro culture. The association between molecular stability and tissue culture in different genetic backgrounds and ploidy levels has already been explored. However, it still remains to be ascertained whether somaclonal variation differs between callus-derived chromosome-doubled and undoubled regenerants. Our research aimed at investigating, through amplified fragment length polymorphism (AFLP) markers, the genetic changes in marker-banding patterns of diploid and tetraploid regenerants obtained from one clone each of Solanum bulbocastanum Dunal and S. cardiophyllum Lindl (both 2n = 2x = 24) and tetraploids from cultivated S. tuberosum L. (2n = 4x = 48). Pairwise comparisons between the banding patterns of regenerants and parents allowed detecting considerable changes associated to in vitro culture both at diploid and tetraploid level. The percentages of polymorphic bands between diploid and tetraploid regenerants were, respectively, 57 and 69% in S. bulbocastanum and 58 and 63% in S. cardiophyllum. On average, the frequencies of lost parental fragments in regenerants were significantly higher than novel bands both in S. bulbocastanum (48 vs. 22%) and S. tuberosum (36 vs. 18%) regenerants. By contrast, in S. cardiophyllum, a similar incidence of the two events was detected (32 vs. 29%). Our results revealed that structural changes after tissue culture process strongly affected the genome of the species studied, but diploid and tetraploids regenerated plants responded equally.

• Korean Journal of Medicinal Crop Science
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• v.26 no.5
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• pp.362-369
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• 2018

Background: For stable induction of tetraploidy in Fallopia multiflora Haraldson, colchicine was treated to establish the condition of induction and investigated the morphological and cytogenetic traits of the tetraploid plants obtained compared to those of diploid ones. Methods and Results: For the induction of tetraploidy, F. multiflora plants were soaked in aqueous solutions of colchicine at various concentration (0.1, 0.5, and 1.0%). After this, 2% dimethyl sulfoxide (DMSO) was added at room temperature on a shaker set at 150 rpm for periods of 12, 24, and 48 h. The induction rate of tetraploids appeared to be the highest in plants treated with 0.5% colchicine for 24 h. As the colchicine concentration and soaking time increased above these levels, the growing tip of the roots did not develop and they began to rot. When compared to diploid plants, tetraploids differed greatly in various characteristics, including the sizes and shapes of the leaves, fruits, flowers and roots. The induced tetraploid F. multiflora had larger guard cells, and chloroplasts, increased number of chloroplast in the guard cells and decreased stomatal densities. Conclusions: When colchicine induced plants for tetraploid, it can be distinguished from diploids, in various characteristics such as morphological changes as stomatal size, number of chloroplasts per guard cell, number of chromosomes and flow cytometry. Therefore, it proved that these methods are suitable, quick and easy methods for the identification of the ploidy level of F. multiflora.