• 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.

• 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.

• Korean Journal of Plant Tissue Culture
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• v.26 no.3
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• pp.149-156
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• 1999

In order to investigate the effect of low temperature pretreatment on pollen dimorphism and embryo formation in anther culture of Platycodon grandiflorum, the anthers with microspore at the uninucleate stage were cultured on Murashige and Skoog medium supplemented with 0.5mg/L NAA and 1.0 mg/L BA. The low temperature pretreatment have clear effect on the frequencies of S pollen grains, symmetrical binucleate microspores (B type of S pollen), multinucleate and multicelled pollen grains. Especially, after low temperature pretreatment at 8$^{\circ}C$ for 5 days increased the frequency of S pollen grain (20.6%) in vivo. In addition, the highest frequency of callus induction (54.9%) and embryo formation (9.9%) were obtained from the anther pretreatment at 8$^{\circ}C$ or 5 days. Three distinct pathways could be recognized in the androgenesis, one involving mainly the vegetative cell, the second starting with the vegetative and the generative cell, respectively, and the third accompaning with two equal vegetative type cells in the pollen grains.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.53 no.2
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• pp.150-155
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• 2008

This experiment was carried out to investigate the effect of proton ion and gamma-ray irradiation on microspore culture of the flower buds of $M_2$ generation in winter type of Brassica napus L. ssp. oleifera. The seeds of three rape varieties, 'Halla', 'Naehan' and 'Tammi' were pretreated with proton ion and gamma-ray 400 Gy and 600 Gy, respectively. When microspore culture techniques were used, embryogenesis was increased in some varieties by proton ion and gamma-ray irradiation treated flower buds of $M_2$ generation than control. In genotypes 'Naehan' showed the highest embryo production frequency, but 'Tammi' showed lowest embryo production frequency. Some of the embryoids developed directly into plantlets, whereas others developed abnormally multilobe. Plants were regenerated and successfully acclimatized in pots.

• Korean Journal of Plant Resources
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• v.18 no.2
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• pp.302-308
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• 2005

This study was carried out to obtain the basic informations on the characteristics of gametophytes formation and embryo developement in Dicentra spectabilis. Microspore mother cells developed from archesporial cells, start meiosis when flower bud length reaches around 1 mm, formed tetrahedral type tetrad. The 4 microspores were separated. They were developed to male gametophytes, respectively. Megaspore mother cells were observed when flower bud length was $4{\sim}5\;mm$. The developemental type of megaspore was polygonum and embryo sac was amphitropous. Three large and distinctive antipodals did not degenerated and remained after embryo sac was developed. When the male and female gametophytes was fully developed, the length of stamen and style was very similar or stamen was shorter about 0.5 mm than that of style. This result indicates that self-fertilization can be occurred in this species. After fertilization, developing zygotic embryos showed various stages of development from globular to cotyledonary embryos, and zygotic embryo in seed scattering time seemed to have an early cotyledonary stage.

• The Journal of Natural Sciences
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• v.6 no.1
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• pp.71-78
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• 1993

Five $F_1$ hybrids of radish(Raphanus sativus L.) were used in the study for induction of microspore derived embryos. Anthers from the mid-uninucleate to early bicellular stage were inoculated on the modified B5 medium and modified Nitch-Nitch medium supplemented with several growth regulators. The efficiency of anther culture was dspendent on the genotype of donor plants and we obtained various culture efficiency from different genotypes. Induction of embryos from microspore was best result on Nitsch-Nitsch media supplemented with 0.1mg/l NAA and 0.05mg/l BAP. Heat treatments of anthers at $35^{\circ}C$-2days and combined with pretreatment of $4^{\circ}C$ for 2, 8, 12 and 16days . Among the treatments, $35^{\circ}C$-2 days treatment combined with $4^{\circ}C$-2days pretreatment treatment were the most effective in developing embryos from microspores.

• Journal of Korean Society of Forest Science
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• v.31 no.1
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• pp.1-7
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• 1976

When haploid plant would be appeared by the anther culture, the large quantity of young plant multiplied maternal inheritance and the same pure line rapidly in the short length of time, which will be effected to cut down much expences efforts and time for the production of seeds or seedlings. Therefore, the development of the technique for this would be much profited in the country industry. In the late of a few years studies were early attempted in this field, but up this time there were a few success of plants only and none of perennial plant. In this status of the country condition required earnestly for the development of the green industry, this researcher attempted to culture the anther of late uninucleate microspore or early binucleate microspore of the Prunus mume and other three psecies, economic trees estimated specially economic, on the place of Modified Murashige and Skoog's medium supliment with Kinetine, 2.4-D, and N.A.A for inducing haploid plants. The obtained results were as follows: 1. 2,000 anthers were cultured and there were shown that 2N callus in Prunus mume had 82 as 4.1%, 2N callus in Prunus tomentosa 15 as 0.8%, 2 N callus in Prunus salisina 75 as 4% 2. N callus had shown 40 as 2% from Prunus armeniaca var. ansu only, and the other trees showed all 2N callus. 3. Callus had appeared in every tree but 2N callus appeared was all filaments and there showed from only connective tissue N callus appeared was all from anther locule inside. 4. Then Prunus armeniaca var. ansu only was not callus of somatic anther tissue origin, but as there was callus origined from microspore which was changed in to swollen microspores or polynucleate microspores, it was certained to need haploid plant.

• Journal of Plant Biotechnology
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• v.41 no.3
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• pp.116-122
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• 2014

Total of fifty accessions of Brassica rapa with various morphological characteristics were used for production of double haploid plants though microspore culture in Brassica rapa. Among them, only 30 accessions induced embryos from microspores. The highest efficiency of embryo induction of 1.194 per bud was obtained from IT135449 of turnip type, while 3 accessions of sarson (winter oil) type did not generate embryo. The effect of heat shock periods for embryogenesis was also investigated with 4 accessions (IT135449; Turnip type, IT199710; Chinese cabbage type, IT212886; Pak choi type, IT218043; Summer oil type). The high productions of embryos were observed in IT135449, IT199710 and IT212886 when microspores were pre-cultured to $32^{\circ}C$ for 2 days. In IT218043, high embryogenesis was observed at the 3 days of heat shock treatment. The optimal condition of shoot regeneration for IT199710 was observed in MS medium supplemented with NAA $0.5mg{\cdot}L^{-1}$ and BAP $1mg{\cdot}L^{-1}$. In contrast, the IT135449 and IT212886 were observed high regeneration frequency in MS medium without plant growth regulators. All the plantlets regenerated from microspore-derived embryos have been successfully transplanted to soil, and bud self-pollinated seeds were produced from doubled haploid plants. This indicated that double-haploid genotype was likely generated naturally during embryogenesis process.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.5
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• pp.394-406
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• 1991

It was proved that cold tolerance of rice plants at the young microspore stage was affected by water temperature and nitrogen application from the spikelet differentiation stage to the young microspore stage, and this mechanism could be explained in the point of view of pollen developmental physiology. The cold tolerance of rice plants at the young microspore stage was severely affected by water temperature (Previous water temperature) and nitrogen application(Previous nitrogen application) from the spikelet differentiation stage to the spikelet differentiation stage. Although the duration is only 10 days or so from the spikelet differentiation stage to the young microspore stage, these days are very important period to confirm the cold tolerance of rice plants at the young microspore stage. The higher previous water temperature up to $25^{\circ}C$ and the deeper previous water depth up to 10cm caused the more cold tolerance of rice plants. Water irrigation of 10cm before the cretical stage showed lower cool injury than that of water irrigation of 20cm during the critical stage. The preventive effect of cool injury by combined treatment of the deep water irrigation before and during the critical stage was not additive but synergistic. The cold tolerance of rice plants grown in previous heavy nitrogen level was rapidly decreased when nitrogen content of leaf blade at the young microspore stage was excessive over the critical nitrogen level. Nitrogen content of leaf blade at the changing point of cold tolerance was estimated as about 3.5% for Japonica cultivars and about 2.5% for Indica x Japonica cultuvars. It is considered that these critical nitrogen contents of leaf blade can be used as a index of the safe critical nitrogen level for the preventive practices to cool injury. It was summarized that increase of engorged pollens per anther by high previous water temperature resulted from the increase of number of differentiated microspores per anther, otherwise, the increase of engorged pollens by the decrease of previous nitrogen level was caused by the decrease of the number of aborted microspores per anther.

• Journal of Korean Society of Forest Science
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• v.43 no.1
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• pp.6-13
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• 1979

In order to substract the time and cost of propagation for inducing the haploid plants per each species. 500 anthers of late uninucleate microspore on early binucleate microspore stage of Robinia pseudoacacia (Fuel tree) Punius granatum (Ornamental tree). Aleurites fordii (Faty tree) and Styrax japonica (Silvicultural tree) were cultured on the modified Murashige and Skoog's medium supplemented with Kinetin, 2.4-D and NAA as growth regulators. And I observed the samples of cultured anthers under the microscope which were made by Microtoming method and Paraffin method. The results were summarized as follows: 1) Among 500 cultured anthers per each species, anther numbers inducing the diploid callus were as follow: Styrax japonica 20 (4% for the species total); Aleurites fordii 10 (2% for the species, total) and Punica granatum 45 (9% for the species total) were showed. 2) 2n Callus were induced from anther wall. but haploid callus were induced from anther locule. 3) Haploid callus were induced only in 25 anthers (5% for the species total) of Robinia pseudoacacia. 4) These haploid callus were not originated from body cell of anther wall tissue, but from reduced microspores, 5) Since already reported many herbaceous haploid plants were induced from the callus which were originated from reduced microspores, I conclude that the anther of woody plant which induced the haploid callus also will be cultured haploid plant.