• Korean journal of applied entomology
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• v.15 no.2 s.27
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• pp.61-68
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• 1976

Leading soybean cultivars such as Kwanggyo, Yugu No.3, Dongbugtae, Gangrim, and Eundaedu were heavily diseased by a virus in Korea. The disease was most severe in the northern provinces where soybean mosaic virus also occurrs, but the disease has also been observed in other provinces where soybean diseases are less prevalent. The disease symptoms were similar to bud blight caused by tobacco ringspot virus; but this was not confirmed in inoculation tests on indicator plants and serological experiments. There were some differences in varietal susceptibility to the disease, with symptom variation depending on the soybean cultivar and source of inoculm. Disease symptoms on infected soybean plants were mottling and necrosis. The present results, therefore, indicate some strains of SMV or a mixture of legume viruses may or may not be responsible for the disease.

• The Plant Pathology Journal
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• v.36 no.6
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• pp.591-599
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• 2020

Phytophthora root and stem rot reduce soybean yields worldwide. The use of R-gene type resistance is currently crucial for protecting soybean production. The present study aimed to identify the genomic location of a gene conferring resistance to Phytophthora sojae isolate 2457 in the recombinant inbred line population developed by a cross of Daepung × Daewon. Singlemarker analysis identified 20 single nucleotide polymorphisms associated with resistance to the P. sojae isolate 2457, which explained ~67% of phenotypic variance. Daewon contributed a resistance allele for the locus. This region is a well-known location for Rps1 and Rps7. The present study is the first, however, to identify an Rps gene locus from a major soybean variety cultivated in South Korea. Linkage analysis also identified a 573 kb region on chromosome 3 with high significance (logarithm of odds = 13.7). This genomic region was not further narrowed down due to lack of recombinants within the interval. Based on the latest soybean genome, ten leucine-rich repeat coding genes and four serine/ threonine protein kinase-coding genes are annotated in this region, which all are well-known types of genes for conferring disease resistance in crops. These genes would be candidates for molecular characterization of the resistance in further studies. The identified R-gene locus would be useful in developing P. sojae resistant varieties in the future. The results of the present study provide foundational knowledge for researchers who are interested in soybean-P. sojae interaction.

• Korean Journal of Breeding Science
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• v.42 no.1
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• pp.35-39
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• 2010

Soybean proteins are widely used for human and animal feed in the world. ${\beta}$-conglycinin protein exhibits poor nutritional and food processing properties and Kunitz trypsin inhibitor (KTI) protein is a main anti-nutritional factor in soybean seed. The objective of this research was to identify the inheritance of $cgy_1$ gene and ti gene for the improvement of soybean cultivar with no KTI proteins and low amount of ${\beta}$-conglycinin. $F_2$ population was made by crossing between "Gaechuck2ho" (${\alpha}^{\prime}$-subunit present $Cgy_1Cgy_1$, KTI protein absent titi) and PI506876 (${\alpha}^{\prime}$-subunit absent $cgy_1cgy_1$, KTI protein present TiTi) parent. A total of 434 $F_2$ seeds were obtained and analyzed for the segregation of ${\alpha}^{\prime}$-subunit protein and KTI protein using SDS-PAGE. The segregation ratio of 3 : 1 for $Cgy_1$ locus (310 $Cgy_1$_ : 124 $cgy_1cgy_1$) and Ti locus (339 Ti_ : 95 titi) were observed. Segregation ratios of 9 : 3 : 3 : 1 (241 $Cgy_1$_Ti_: 69 $Cgy_1$_titi: 98 $cgy_1cgy_1$Ti_: 26 $cgy_1cgy_1titi$) between $Cgy_1$ gene and Ti gene in $F_2$ seeds were also observed (${\chi}^2= 5.367$, P = 0.10 - 0.20). This data showed that $Cgy_1$ gene was inherited independently with the Ti gene in soybean. These results will be useful in breeding program for selecting the line that does not exhibit or lacks both ${\alpha}^{\prime}$-subunit protein and KTI protein in soybean.

• The Plant Pathology Journal
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• v.15 no.1
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• pp.1-7
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• 1999

The production of soybean cyst nematode (SCN), Heterodera glycines, including female formation and fecundity was much higher in SCN race 14 (R14) than in race 3 (R3) in susceptible soybean cultivars Bragg (intolerant), Lee74 (moderately tolerant), and PI 97100 (highly tolerant). The nematode body was also significantly larger in R14 than in R3 at 20 days after inoculation, but the further nematode growth appeared to be slower in R14 than in R3, resulting in no significant difference between the two races at 30 days after inoculation. Within each race, no significant difference was observed in the growth and reproduction among the soybean cultivars tested. Syncytial areas near the nematode lip regions (infection sites) were measured for each soybean cultivar-SCN race combination. R14 induced significantly larger syncytia than R3. Bragg had relatively larger syncytia than Lee74 and PI 97100, but the difference among the soybean cultivars was minimal or not significantly different. Syncytium occupation in the stelar region differed only between PI 97100 and the other two cultivars, which may be somewhat, but not exactly, related to tolerance levels. Syncytial cytomplasm was degenerated more with R14 and in Bragg than with R3 and in Lee74 and PI 97100, respectively. In light microscopy, degenerated syncytia were characterized by depleted and loose cytoplasm with less plastids than normal-looking (intact) syncytia which had dense syncytial cytoplasm. Electron microscopy revealed that degenerated syncytia contained highly vacuolated cytoplasm with degenerated plastids. The above results suggest that structural characteristics of syncytia may match the nematode growth and reproduction.

• The Plant Pathology Journal
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• v.35 no.3
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• pp.219-233
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• 2019

Soybean cultivars susceptible to Phytophthora root and stem rot are vulnerable to seed rot and damping-off of seedlings and young plants following an infection by Phytophthora sojae. In this study, the disease responses of Japanese soybean cultivars including currently grown main cultivars during the early growth stages were investigated following infections by multiple P. sojae isolates from Japanese fields. The extent of the resistance to 17 P. sojae isolates after inoculations at 14, 21, and 28 days after seeding varied significantly among 18 Japanese and two US soybean cultivars. Moreover, the disease responses of each cultivar differed significantly depending on the P. sojae isolate and the plant age at inoculation. Additionally, the treatment of 'Nattosyo-ryu' seeds with three fungicidal agrochemicals provided significant protection from P. sojae when plants were inoculated at 14-28 days after seeding. These results indicate that none of the Japanese soybean cultivars are completely resistant to all tested P. sojae isolates during the first month after sowing. However, the severity of the disease was limited when plants were inoculated during the later growth stages. Furthermore, the protective effects of the tested agrochemicals were maintained for at least 28 days after the seed treatment. Japanese soybean cultivars susceptible to Phytophthora root and stem rot that are grown under environmental conditions favorable for P. sojae infections require the implementation of certain practices, such as seed treatments with appropriate agrochemicals, to ensure they are protected from P. sojae during the early part of the soybean growing season.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.4
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• pp.279-283
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• 2004

This experiment was carried out at paddy field (commercial silty loam soil) in the southwestern Korea. Pungsannamulkong, a determinate growth habit, was a relatively high yielding and late maturing cultivar, and Han­namkong, a semi determinate growth habit, was a relatively low yielding and early maturing cultivar. Seeds were sowed at two plants and with a planting density of $70{\times}10cm$ on May 26, 2003. Fertilizer was applied prior to planting at a rate of 3.0-3.0-3.4g $(N-P_2O_5-K_2O)\;per\;m^2$ by all basal fertilizations. Experimental design was a randomized complete block with three replications. Seed yield was higher in Pungsannamulkong by 362g per $m^2$ than in Hannamkong of 260g per $m^2$ Also, the number of pod, number of seed, and number of seed per pod were greater in Pungsannamulkong than in Hannamkong. The number of leaves per $m^2$ showed similar with two soybean cultivars up to August 24 but thereafter it decreased in Hannamkong. The leaf area up to August 4 increased in Hannamkong higher than in Pungsannamulkong, but after that time, Pungsannamulkong had greater leaf area than Hannamkong. The shoot and leaf dry matter of two soybean cultivars from June 23 to August 4 were similar but thereafter, Pungsannamulkong had a significantly greater than Hannamkong. Crop growth rate (CGR), relative growth rate (RGR) and net assimilate rate (NAR) for Punsannamulkong were relatively higher than Hannamkong but leaf area ratio (LAR) and specific leaf weight (SLW) showed higher in Hannamkong. Most of leaves distributed in the ranges of 80-90cm and 60-70cm from the soil surface in Punsannamulkong and Hannamkong, respectively. Pods of Punsannamulkong ranged 10-80cm from the soil surface and most of pods were distributed at 40-50cm. Photosynthetic rate at the flowering stage showed a significant difference between cultivars in the upper most leaf position. There was no significant difference of the photosynthetic rate at $7^{tn}$ leaf at the flowering stage, and the uppermost and 7th leaf position at the seed development stage between two soybean cultivars.

• Research in Plant Disease
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• v.16 no.2
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• pp.176-182
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• 2010

Occurrence of plant diseases is dependent on various factors in the agricultural system. Due to recent extensive environmental climate changes, i.e. global warming, agricultural systems such as planting dates and cultivars are being affected. Gradual transition in disease occurrence and incidence in the agricultural fields can also be affected by direct and/or indirect environmental changes. In this study, we evaluated disease occurrence and incidence in soybean plants to investigate whether it could be related with cultivars, planting dates and geographical differences in Korea in 2008. Soybean cultivars including 'Taekwang', 'Pungsan', 'Cheongja 3', 'Saeol', and 'Dawon' were planted in four different dates, May 15, June 1, June 15, and June 30, in two locations, Suwon, and Naju. Soybean diseases such as wild fire and bacterial pustule were mainly found depending on cultivars, planting dates, and areas. Wild fire occurred severely on cv. 'Taekwang' while bacterial blight did on cv. 'Dawon' among tested cultivars. Disease developments of wild fire and bacterial blight generally decreased in delayed planting regardless of cultivars.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.149-149
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• 2022

As the average temperature rises due to climate change, damage to caused by rising temperatures is spreading all over the world. If soybeans are exposed to high temperature during the reproductive stage, pod setting rate and seed weight is reduced, therefore, various studies are needed to prevent crop damage due to high temperature. This study is to research the effect of high temperature on yield decrease during the grow stage of soybean.

• Proceedings of the Korean Society of Crop Science Conference
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• 2005.04a
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• pp.116-117
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• 2005

• Proceedings of the Korean Society of Crop Science Conference
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• 2006.04a
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• pp.342-343
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• 2006