• International Journal of Industrial Entomology and Biomaterials
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• v.5 no.1
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• pp.59-65
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• 2002

Parthenogenetic development, hybrid vigour and cocoon shape variability were studied in bivoltine F1 hybrids of the silkworm, Bombyx mori L. Considerable breed differences were observed in parthenogenetic ability. Among the parental breeds, CSR18 exhibited maximum parthenogenetic development (79.65%) followed by CSR4 (67.90%). Among bivoltine F1 hybrids, CSR18 ${\times}$ CSR4 showed highest parthenogenetic development (73.32%) followed by CSR2 ${\times}$ CSR4 (55.43%). Study on hybrid vigour demonstrated that CSR18 ${\times}$ CSR19 expressed maximum significant hybrid vigour for all the seven economic characters over Mid Parent Value (MPV) followed by CSR2 ${\times}$ CSR4 and CSR18 ${\times}$ CSR4 exhibiting significant heterosis for six characters. Cocoon shape measurement study revealed that among ten bivoltine F1 hybrids, cocoons of three hybrids were found comparatively uniform. Importance of this study to know the level of paythenogenetic development, hybrid vigour and cocoon shape variability in different bivoltine F1 hybrids have been discussed.

• Korean Journal of Plant Tissue Culture
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• v.25 no.2
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• pp.135-139
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• 1998

Reciprocal interspecific hybrids between N. glauca(2n=24) and N. langsdorffii(2n=18) were obtained by intercrossing. One hundred percent of F$_1$ seeds was produced from intercrossing of N. glauca $\times$ N. langsdorffii, whereas the frequency of F$_1$ hybrid seed formation from N. langsdorffii $\times$ N. glauca was very low. However, all the hybrid seeds were germinated well and then grown to normal plantlets. All the plants of F$_1$ hybrids have chromosome number of interspecific hybrids (2n=21). From observation of morphological characteristic, the structure of petrol, leaf, flower, and the morphology of pollen have characteristics of F1 hybrid. Spontaneous tumors (genetic tumor) were formed from each F$_1$ hybrid; the genetic tumor arose at the reproductive phase when the maternal type of F$_1$ hybrid came from N. glauca, while the genetic tumor arose only after reproductive phase when the maternal type of F$_1$ hybrid came from N. langsdorffii. The genetic tumor actively proliferated on hormone-free medium and produced numerous teratoma shoots. In addition, normal leaf or stem explants of F$_1$ hybrid produced calli on hormone-free medium after 15 days of culture, the calli produced new numerous teratoma shoots after 30 days. The frequency of teratoma shoot formation from rnterspecific hybrid was higher in the N. glauca $\times$ N. langsdorffii than in the N. langsdorffii $\times$ N. glauca. Root development from the teratoma shoots was hardly obtained. Teratoma shoots without roots in vitro can form genetic tumor at the vegetative growth phase after tissue culture.

• Journal of Sericultural and Entomological Science
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• v.4
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• pp.51-55
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• 1965

The aim of this work was to investigate the rate of hybrid vigor among the $F_1$ hybrids. The results obtained are as follows; 1. The rate of hybrid vigor in outbreedings(E$\times$J, ＆ J$\times$C) was higher than that in inbreedings in all the metric characters, especially in moulting laval weight. 2. In outbreedings, the $F_1$ between Europe and Chinese strain showed considerably higher rate of hybrid vigor than that of Japanese and Chinese. 3. The hybrid vigor rate of moulting larvel weight gave rise to be significant differences among the strains due to the maternal effects from newly hatched larvae to pupae.

• Journal of Plant Biotechnology
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• v.44 no.3
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• pp.208-219
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• 2017

Heterosis or hybrid vigor describes a phenomenon that superior phenotypes compared to the two parents are observed in the heterozygous $F_1$-hybrid plants. Identification and characterization of heterosis-related genes (HRGs) will facilitate hybrid breeding in crops. To identify HRGs in Brassica rapa, we analyzed transcriptome profiling using a Br300K microarray in non-heading Chinese cabbage at three developmental stages. A large number of genes were differentially expressed in $F_1$ hybrids and non-additive expression was prominent. Genes that are expressed specifically for $F_1$ hybrid at all three stages were Brassica-specific uncharacterized genes and several defense-related genes. Expression of several photosynthesis- and stress-related genes were also $F_1$ hybrid-specific. Thirteen NBS-LRR class genes showed high and specific expression in $F_1$ hybrid Shulu: some of them were characterized as defense genes in Arabidopsis, but most have not been. Further characterization of these defense-related genes in Brassica species and its application will be helpful for understanding the role of defense responses in heterosis. In addition, results obtained in this study will be valuable to develop molecular markers for heterosis and disease resistance in B. rapa.

• Korean Journal of Breeding Science
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• v.41 no.4
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• pp.463-467
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• 2009

Interspecific hybrid plants between Allium cepa L. (2n=2X=16) and A. fistulosum L. (2n=2X=16)and their backcross lines were developed by artificial pollination in order to introduce new desirable characters of A, cepa to A. fistulosum. The 2C nuclear DNA content has been estimated by flow cytometry in 5 Allium fistulosum inbreed lines, 2 interspecific hybrid lines of A. cepa${\times}$A. fistulosum and 34 their backcross lines $BC_1F_1$ to $BC_2F_2$, using propidium iodide (PI) as a fluorescence dye. Estimated 2C DNA values ranged from 22.2 pg to 23.7 pg in 5 A. fistulosum inbreed lines, 37.9 pg in F1 hybrid between A. cepa and A. fistulosum, 24.3 pg to 27.3 pg in 7 backcross lines in $BC_1F_1$, 21.9 pg to 24.4 pg in 9 $BC_1F_2$, 22.9 pg to 25.1 pg in 14 $BC_2F_1$, 22.6 pg to 23.4 pg in 4 $BC_2F_2$. This study showed mean 2C nuclear DNA content of $F_1$ hybrid was higher than their backcross progeny lines, while it was lower than female parental line, A. cepa (2C DNA=33.2 pg). Mean 2C DNA content of backcross lines, $BC_1F_1$ to $BC_2F_2$ was not significantly different but their 2C DNA contents in the more progress generation from $BC_1F_1$ to $BC_2F_2$ were reduced.

• Journal of The Korean Society of Grassland and Forage Science
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• v.11 no.1
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• pp.1-5
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• 1991

Tall fescue(Festuca amndinacea Schreb.) is a productive pasture grass that is widely adapted to the soil and climate of Korea. It is regarded, however, as relatively low in palatability and nutritive value. On the other hand, Italian ryegrass(lo1ium rnultz$om Lam.) is highly nutritious and palatable, but is essentially weak in cold tolerance. Numerous investigators have succeeded in producing hybrids between Lolium spp. and Festuca spp. but no improved varieties have resulted. Therefore, intergeneric hybridization of Italian ryegrass with tall fescue is employed in 1984 to improve the adaptive and cold resistance quality of Italian ryegrass. In the mean time, F1-hybrid plants obtained by crossing Italian ryegrass x tall fescue were observed in open field. The results are summarized as follows: 1. Leaf-size and silica cell hair were intermediate between the types of parents but the shape of auricle tended to show Italian ryegrass and auricle-cilia to show tall fescue. 2. Roots of $F_1$-hybrid plants were mainly distributed at top soil and did not produced florescence material. 3. Head type of hybrids was intermediate between the types of parents but ray length was somewhat less than the length of tall fescue ray. Typical Italian ryegrass or tall fescue-like phenotypes were not observed. 4. Anthers of $F_1$-hybrid plants were formed but pollen were not formed. Even though pollen were formed, they were all empty. 5. Hybrid plants were more winterhardy and summer persistency than Italian ryegrass. They showed a equivalent growth to Italian ryegrass in spring and to tall fescue in summer. 6. Chromosome of $F_1$-hybrids was allopolyploid(2n=4~=28) and all $F_1$-hybrid plants were sterile.

• Journal of Korean Society of Forest Science
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• v.43 no.1
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• pp.1-5
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• 1979

The arrangement and the number of vascular bundle in petiole were investigated with the hybrid Populus alba${\times}$P. glandulosa and both parents. 1. The variation in number and the arrangement of the vascular bundle in petiole were smaller at middle point than at nearer point to the leaf blade. 2. A small variation was found in the arrangement of the vascular bundle within a tree, same clone and same species. 3. Five shapes of vascular bundle were recognized in the $F_1$ hybrid, 26.7 per cent of the $F_1$ hybrid has the same shape with P. alba, 13.3 percent with P. glandulosa and 53.3 per cent of the $F_1$ hybrid shows the $F_1$ shape caused by hybridization. 4. The hybrid clones which show the same shape with P. alba are 66-20-1, 66-6-8, 65-22-11 and 64-6-44, hybrid clones of 65-95, 66-14-93 have the same shape with P. glandulosa. Hybrid clones of 66-15-3, 67-6-3, 65-22-4, 66-26-55, 68-1-54, 66-14-99, 65-29-19, 66-25-5 have $F_1$ shape.

• Journal of Ginseng Research
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• v.27 no.4
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• pp.183-187
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• 2003

This study was carried out to ascertain the basic information on characteristics of Korean Ginseng(Panax ginseng) and American ginseng(Panax quinquefolius), F$_1$ hybrids. Interspecies hybrids between Panax ginseng and Panax quinquefolius were examined morphological characteristics, rusty root incidence, and contents of effective ingredients such as ginsenosides. The summarized results are as follows. In Panax ginseng, rusty root incidence tended to increase with age of ginseng, but there was no difference in the incidence among ginseng ages and cultivation years in Panax quinquefolius and F$_1$ hybrid. The interspecies hybrid of panax ginseng and Panax quinquefolius flowered later than the Panax ginseng, but earlier than the Panax quinquefolius. As for the characteristics of ginseng root, Panax quinquefolius seedling was better than cv. Panax ginseng, as the former had longer and heavier seedling root than the latter. Ginsenosides of the hybrid F$_1$ showed intermediate value in amounts of Rb$_1$, Rb$_2$, Rc and Rd which were detected as in Panax gineng and Panax quinquefolius. The amount of Re of the hybrid was higher, but that of Rg$_1$ and Rg$_2$ in main and branch roots was lower compared with its parents. Rf was 0.14% and 0.20% in main and branch roots of Panax ginseng, respectively; however, no Rf was detected in Panax quinquefolius and in the hybrid F$_1$. This suggests there may be remarkable difference in Rf content among the ginseng species.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.14
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• pp.123-131
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• 1973

1. In order to evaluate the performance of the $F_2$ and $F_3$ generations of $F_1$ varietal crosses which in past trials yielded better than or as high as the recommended double-cross hybrids, eleven yellow and five white-endosperm $F_1$ varietal crosses, their $F_2$ and $F_3$ generations, and the parental open-pollinated varieties together with the standard double-cross hybrids were tested in performance trials in the 1963 wet and 1963-64 dry seasons. The former trials, however, failed due to a strong typhoon that damaged the crop. 2. Net hybrid vigor was highly manifested in grain yield in the $F_1$ varietal crosses, which on the average was 39.9 per cent of the mid-parent yields. Reduction in heterosis was 27.2 per cent in the $F_2$and 30.3 per cent in the $F_3$ generation, respectively. 3. A fairly high degree of reduction in yield occurred in the $F_2$ and $F_3$ generation. On the average, the $F_2$ generation decreased by 17.6 per cent and the $F_3$ by 20.7 per cent. The losses in two generations were exhibited in two levels; four crosses decreased by 10.9 per cent and twelve combinations by 22.0 per cent. The advanced generations of one yellow cross, Cuban Yellow Flint ${\times}$ Hawaiian Flinty Dent, and three white flint crosses, Bicol White Flint ${\times}$ Eto Blanco, College White Flint ${\times}$ Eto Blanco and Bicol White Flint ${\times}$ Nariono 330b, yielded as high as Philippine Hybrid No.1 and Philippine Hybrid No.4, respectively. 4. No significant differences in yield were obtained between the $F_2$ and $F_3$ populations, showing that genetic equilibrium was reached in $F_2$, as may be expected in view of the Hardy-Weinberg law on panmixis. 5. As in past trials, Hawaiian Flinty Dent, a variety, yielded as high as Philippine Hybrid No. 1.

• Journal of Microbiology
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• v.38 no.2
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• pp.113-116
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• 2000

Escherichia coli F plasmid partition apparatus is composed of two trans-acting proteins (SopA and SopB) and one cis-acting DNA sequence (sopC). The SopB-sopC complex has been suggested to serve a centromere-like function through its interaction with chromosomally encoded proteins which remain to be identified. In this paper, we are introducing a new yeast 1.5-hybrid system which assembles the two-hybrid and one-hybrid system as a mean to find and additional component of the F plasmid partition system, interacting with DNA (sopC)-bound SopB protein. The results indicates that this system is a promising one, capable of selecting an interacting component.