• The Plant Pathology Journal
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• v.28 no.4
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• pp.418-422
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• 2012

Eleven hot pepper accessions collected in Vietnam showed stable resistance to bacterial wilt as well-known resistance sources, MC4 and MC5, in repeated inoculation tests with different Ralstonia solanacearum isolates conducted from 2004 to 2010. Seven of these accessions (specifically KC981, KC1006, KC1021, KC1027, KC1045, KC1050, and KC1055) resulted in stable male sterile F1 plants in the crosses with a cytoplasmically male sterile (CMS) Chilseong (CMS-A, Srfrf ), and therefore, they were maintainers (CMS-B) with a genotype of Nrfrf. The rest (KC980, KC995, KC999, and KC1009) produced stable male fertile F1 plants in the crosses, and therefore, were restorers (CMS-C) with a genotype of N(S)RfRf. Therefore, the maintainer and restorer sources of resistance may be used in preference in breeding maternal (CMS and their maintainers) and paternal parents (restorers) for resistance to bacterial wilt, respectively, in the hybrid breeding system utilizing cytoplasmic male sterility.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.12
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• pp.7-14
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• 1972

Four treatment leveles(check 500, 1, 000 2, 000ppm) of Ethrel were applied to barley and wheat grown in greenhouse and fields at three stages (preboot, boot, afterboot) of growth in orderd to induce male sterility and to evaluate possibility of practical $F_1$-hybrid-seed production as gametocide. The results are summarized as follows. 1. The shortening plant height, especially the first internode length. spike length and decreasing 1, 000 seeds weight and induction of male sterility, were observed with all Ethrel theatments. The earier the stage of spraying at the boot and the higher concentration of Ethrel, the greater effects were observed. 2. The most practical level of inducing male sterility occurred ranging from 1, 000-2, 000ppm applied at all stages, while with increasing maturity, greater concentration of Ethrel were required to induce the same level of male sterility. .3. Great differences for male sterility per spike in bagged and unbagged spikes were shown with all treatments indicated ovary receptiveness, and that out-crossing has taken place, 4. Ethrel treatment induced more practicable extent of male sterility in barley than wheat. This results indicated that $F_1$-hybrid-seed production in barley with gametocide appears feasible if high combining ability lines were selected for increased out-crossing ratio. 5. There seemed to be no indication of additive surfactant influence on the Ehrel action in the present studies, and showed an interest on further studies on this matter.

• Molecules and Cells
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• v.25 no.1
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• pp.20-29
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• 2008

Cytoplasmic male sterility (CMS), one of the most important traits in crop breeding, has been used for commercial seed production by $F_1$ hybrid cultivars of pepper (Capsicum annuum L.). To develop reliable molecular markers for allelic selection of the Restorer-of-fertility (Rf) gene, which is known to be a major determinant of pollen fertility restoration in peppers, a sequence of approximately 10 kb flanking an RAPD fragment closely linked to the Rf locus was obtained by genome walking. A homology search revealed that this sequence contained an LTR retrotransposon and a non-LTR LINE-like retrotransposon. Sequencing of this Rf-linked region to search for polymorphisms between a dominant and recessive allele revealed 98% nucleotide sequence identity between them. A third polymorphic haplotype of the Rf-linked sequence, which has 94-96% nucleotide sequence identity with the two previously isolated haplotypes, was identified among a large number of breeding lines. Utilizing polymorphic sequences in the haplotypes, PCR markers were developed for selection of particular haplotypes and used to examine the distribution of the haplotypes in diverse breeding lines, cultivars, and C. annuum germplasms. Surprisingly, the third haplotype was the predominant type in C. annuum germplasms, while its frequency in $F_1$ hybrid cultivars was relatively low. Meanwhile, analysis of breeding lines whose Rf allele genotypes and male-sterility phenotypes were already known revealed that the third haplotype was mainly present in exotic breeding lines that cause unstable male-sterility when combined with sterile cytoplasms.

• Horticultural Science & Technology
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• v.17 no.4
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• pp.470-472
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• 1999

When the type and ratio of male-sterile plants in $F_1$ hybrids collected from several seed companies were investigated, there were differences in the male-sterile type depending upon region, seed company and variety group. The differences were inferred due to the easiness in breeding of maintainer line among the variety groups. American seed companies mainly used petaloid type male sterility with Imperater group varieties. European companies used brown anther type male sterility mainly with Nantes group but some companies used petaloid type also in varieties that were different from Nantes group. Asian companies (Japan, Korea) used both types with Chantaney and Kuroda group varieties, but one type was mainly used depending on individual seed company. Only one type of male-sterility in one variety was observed and the results were agreed well with other's results that male-sterility type was determined by cytoplasm factor. Some breeding lines were backcrossed to both types of cytoplasm (Sa, Sp) for maintainer line selection. We could select 15 maintainer lines from 20 lines in petaloid cytoplasm (Sp) and 3 from 4 lines in brown cytoplasm (Sa). In petaloid cytoplasm, maintainer lines can be selected at considerably high frequency. But in brown anther cytoplasm, the used materials are too restricted to tell general frequency maintainer lines.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.45 no.5
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• pp.347-351
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• 2000

Rye has been a major winter forage crop in Korea. Varietal improvement of rye has been practiced either by hybrid or population breeding systems. Hybrid breeding offers important advantages over population breeding since it is normally a cross-pollinated crop. The hybrid breeding in rye has been possible since cytoplasmically inherited forms of male sterility (CMS) and corresponding nuclear restorer genes were found. The objectives of this research were to develop the maintainer and restorer lines of Korean inbred lines and to estimate the effect of 'Pampa' type of CMS cytoplasm on yield and its related characteristics. For easy discrimination of male-sterile status of plants, anther scoring and the restore index system in which seed-setting and pollen quantity of viability were taken into account were established. High significant correlation between pollen quantity and pollen viability was found. For "Pampa" cytoplasm, four of 14 Korean inbred lines tested turned out to be a maintainer but no restorer was found. But for "235b" CMS cytoplasm, seven inbred lines acted as complete restorers. The Korean inbred rye lines acted mainly as maintainers in "Pampa" cytoplasm but acted mainly as restorer in "235b" cytoplasm. The 'Pampa' cytoplasm inducing male sterility reduced cohn length and plant height and increased the number of tiller, so forage yield and grain yield were enhanced. However, heading date was slightly delayed compared to the normal cytoplasm.elayed compared to the normal cytoplasm.

• KSBB Journal
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• v.8 no.2
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• pp.97-103
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• 1993

This study was investigated as a step for the purpose of successful introduction of cytoplasmic inherited characters between the different plants. Cytoplasts were separated from the protoplasts of CMS(cytoplasmic male sterility) line such as MS Burley 21 which carried from Nicotiana megalosiphon. The cytoplasts were fused to protoplasts derived from Nicotiana tabacum Br 64 with PEG(polyethylene g1yco1). The cytoplasts were separated by density gradient centrifugation. Efficient separation of cytoplasts depended on the difference of specific density of gradient solution. However, the iso-osmolality of gradient solution was not important to separate the cytoplasts. The cells for a cybrid were fused with 50% concentration of PEG.

• Journal of the Korean Society of Tobacco Science
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• v.1 no.1
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• pp.46-50
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• 1979

Four cytoplasmic male-sterile lines of burley tobacco (Nicotiana tabacum L. ) and their male- fertile counterparts were evaluated for their characteristics in replicated field trials. Cytoplasmic male -sterile lines were comparable to the male- fertile varieties for agronomic and chemical traits and these suggest that the cytoplasmic male - sterility can be used in the production of hybrid seed without loss of vigour or undesirable changes On other characteristics.

• Journal of the Korean Society of Tobacco Science
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• v.2 no.1
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• pp.28-37
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• 1980

This experiment was carried out to evaluate the utilization of F, hybrids using cytoplasmic male sterility in Burley tobacco. Four cytoplasmic male sterile lines and their male-fertile counterparts and 21 Fi hybrids and their parents were evaluated for their agronomic performance in replicated field trials. Some F1 hybrids were comparable to Burley 21, the only Burley cultivar in Korea. Among 21 F1 hybrids, MS L8$\times$Burley 49 and three other hybrids showed 2-11% and 1-5% higher yield and price per kg than Burley 21, respectively.

• Plant Resources
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• v.7 no.2
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• pp.127-135
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• 2004

We characterized the resistances such as to waterlogging, Phytophythora and viruses in hybrids between Italian and Korean mother lines and screened them for complex resistances and agronomic traits to select elite multi-resistant lines for hybrid breeding. Resistance to waterlogging was selectable due to diversity of the resistance. Phytophythora resistance introduced from Italian lines could also be combined with resistance to other diseases and restoration abilities from cytoplasmic male sterility that has been maintained in Korean varieties.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.25 no.2
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• pp.49-57
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• 1980

A $F_1$ hybrid out of 143 crosses of rape (Brassica napus) using cytoplasmic-genetic male sterility yielded 5.18 tons per hectare. European and native varieties used, were found out to have 78% and 58% of genes restoring fertility, respectively. The $F_1$ hybrids of three way cross using non-isogenic maintainer showed higher heteroses than those of double cross. To produce F 1 hybrids of three way cross, three stages of crossing operations are needed and seeds produced from about 60 hectares can be covered to 60, 000 hectares.