• 식물조직배양학회지
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• 제24권4호
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• pp.239-256
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• 1997

Plants belonging to the category of 2n apomixis or agamospermy form embryos and seeds without the processes of normal meiosis and syngamy. Seeds produced in this way have identical genotype of their maternal parent. Three different types of agamospermy are recognized: diplospory, apospory, and adventitious (adventive) embryony. $F_1$ hybrid cultivars cannot be used as seed sources in the next ($F_2$) generation because this generation would be extremely variable as a result of genetic segregation. Hybrid vigor is also reduced in the $F_2$ generation. Therefore, parental stocks for hybrid seed production need to be maintained and cross must be continuously repeated. Agamospermic 2n apomixis would make it possible to fix the genotype of a superior variety so that clonal seeds faithfully representing that genotype could be continuously and cheaply produced independent of pollination. That is, $F_1$ hybrid seeds could be produced for many generations without loss of vigor or genotype alteration. Production of apomictic $F_1$ hybrid seed would be simplified because line isolation would not be necessary to produce seed or to maintain parental lines, and the use of male-sterile lines could be avoided. Overall, apomixis would enable a significant reduction in hybrid seed production costs. Additionally, the production of clonal seed is not only important for seed propagated crops, but also for the propagation of heterozygous fruit trees and timbers. Clonal seed would help avoid costly and time-consuming vegetative propagating methods that are currently used to ensure the large-scale production of these plants. Apomixis is scattered throughout the plant kingdom, but few important agricultural crops possess this trait Therefore, most research to date has centered on introgressing the trait of apomixis into agricultural crops such as wheat, maize, and some forage grasses from wild distant relatives by traditional cross breeding. The classical breeding approach, however is slow and often impeded by many breeding barriers. These problems could be surmounted by taking mutagenesis or molecular approach. Arabidopsis thaliana is a tiny sexually reproducing plant and is convenient in constructing and screening in molecular researches. Male-sterile mutants of Arabidopsis are particularly suitable genetic background for mutagenesis and screening for apomictic mutants. Molecular approaches towards isolating the genes controlling the apomictic process are feasible. Direct isolation of genes conferring apomixis development would greatly facilitate the transfer of this trait to wide variety of crops. Such studies are now in progress.

• 한국작물학회지
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• 제37권5호
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• pp.476-485
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• 1992

1. 옥수수의 자식계 9계통에 화학적 돌연변이 유기제를 처리하여 얻어진 M$_1$, 식물들은 형태적으로 왜성화, 백색화등 다양한 변이체로 나타났고 생식기관의 변이는 자성개체, 웅성개체, 자웅동화, 다수성들을 보였고 부임개체들이 증가하였다. 2. mutagen의 종자침지처리후 이삭에 수분방지대를 씌웠을때는 3.9-11.2%의 이삭착립율이 나타났으나 이삭당 성숙립수는 3.8-4.3게에 불과하였다. 한편 mutagen의 이삭주입처리에서는 5.1-10%의 착립이삭율과 이삭당 성숙립수는 1.7-6.3이었고 자연수분후 4시간만에 웅사를 절단하였던 이삭들은 착립이삭수가 27%로 증가하였다. 3. Mutagen처리와 수분방지처리에서 형성된 종자들의 조직학적 관찰은 aposporous apomictic reproduction이나 adventitious embryony의 가능성을 보여주었고 M2식물의 근단염색체를 조사하였을때 모두 2배체로서 확인되었다. 4. 무배합생식성 종자에서 출현된 식물들은 초장의 변이계수가 4-6%로 비교적 낮았고 외부형태상의 균일성을 보여주었다. 그러나 이들 무배합생식성과 결부된 표식형질을 발견할수는 없었다.

• Journal of Plant Biotechnology
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• 제5권2호
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• pp.87-93
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• 2003

Brachiaria (Poaceae) is the most important forage genus for cattle production in Brazil. The genetic breeding of this genus is limited by the incompatibility among species, differences in ploidy level and the natural cloning of plants by apomixis (Valle and Miles 1992). However, plant regeneration via tissue culture methods and genetic engineering provide an opportunity to introduce new characteristics in plants of this genus. We have developed methods for the 'genetic modification of Brachiaria brizantha cv. Marandu via biolistic transformation. A higher number of shoots was obtained with 4 mg/L 2.4-diclorophenoxyacetic acid and 0.2 mg/L benzylaminopurine in calli induction medium and 0.1 mg/L naphtaleneacetic acid and 4.0 mg/L kinetin in shoot regeneration medium. A selection curve for mannose was determined to use phospho mannose isomerase (PMI) gene of Escherichia coli as a selection marker. Calli formation was inhibited from 5 g/L mannose, even in the presence of sucrose while calli that were formed in the presence of mannose failed to develop embryos showing that PMI gene can be used for selection of transformants of this grass. Different promoters were tested to evaluate the efficiency based on the detection of the GUS gene expression (Jefferson et al. 1987). The monocot promoters, act1-D and ubi-1, resulted in higher expression levels than dicot promoters, ubi-3 and act-2, or the CaMV35S and CVMV promoters.

• 원예과학기술지
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• 제28권4호
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• pp.618-626
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• 2010

장미속 종간교잡 후대에서 발견되는 경모유전(matroclinal inheritance) 현상은 세포질 유전, 단위결과, 그리고 비대합적 배우자생식(asynaptic heterogamy)의 결과로 설명될 수 있다. 비대합적 배우자생식은 $Caninae$ 아절($Rosa$ $hybrida$ L. sect. $Caninae$ DC.)의 종간교잡에서 독특하게 관찰되며, 5배체의 경우, 화분세포를 통해서는 2가염색체(2x=14)를 이루는 상동게놈 중 한 게놈(x=7)만이, 난세포에서는 이러한 게놈(x=7)과 더불어 1가 염색체를 이루는 나머지 게놈들(3x=21)이 동시에 유전되어 후대에서 종자친의 배수성(5x=35)이 회복된다. 본 연구에서는 절화장미 품종간 정역교배시 대립유전자의 후대유전 빈도를 관찰함으로써, 4배체 품종교배에서 관찰되는 경모유전의 요인을 분석하고자 하였다. 절화장미 6품종을 이용한 6개 정역교배조합 당 8개의 후대개체를 총 30개의 EST-SSR 마커로 검정해 본 결과, 뚜렷한 세포질 유전의 경우는 발견되지 않았다. 또한, 단위결과의 경우도 'Redtem' ${\times}$ 'Red Sandra' 조합의 후대개체 하나에서만 발견되어, $Caninae$ 아절의 종간교잡에서와 비교하여 상당히 낮은 빈도였다. 비대합적 배우자생식의 예도 $Caninae$ 아절의 경우처럼 뚜렷하게 나타나지는 않았다. 하지만, 6개 공시품종 중, 4개의 품종에서 화분친 보다 종자친으로 교배시 품종 특이적 마커의 후대유전빈도가 상대적으로 높게 나타나 품종에 따라 대립유전자의 모계유전적 성향이 존재함을 증명하였다. 특히 'Yellow King'의 경우, 11개의 대립유전자 중 10개가 종자친일 경우에 후대집단에서 높은 빈도로 나타나 공시품종 중 가장 강한 모계유전성을 보였다.