• The Korean Journal of Pesticide Science
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• v.7 no.3
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• pp.216-222
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• 2003

In order to develop effective control methods for Bakanae disease caused by Gibberella fujikuroi (Saito) Ito during rearing of rice seedlings, we investigated the disease resistance of 15 rice varieties to G. fujikuroi and control effect of six seed disinfectants, and tried to improve the using methods of the seed disinfectants. Disease resistance was tested by investigating the disease incidence on each rice cultivar grown in rice seedling box infested with or not infested with G. fujikuroi at 30 days after sowing seeds and 20 days after heading date. The results showed that Hwayongbyeo, Dongjinbyeo, Hwoanbyeo, Nonghobyeo, Nampyeongbyeo, and Hwojinbyeo were resistant G. fujikuroi, meanwhile Keulubyeo, Sobibyeo, Odaebyeo, Junambyeo, Samchonebyeo, Sangjubyeo, and Hwabongbyeo were susceptible. Three seed disinfectants, prochloraz, fludioxonil, and carproamid + thiram + fludioxonil controlled Bakanae disease of rice very well, while bonomyl + thiram, thiophanate-methyl + thiram and thiophanate-methyl + triflumizole did not suppress the disease enough. Water temperature was turned to be an important factor for controlling the disease by treating seed disinfectants. Prochloraz showed 61% control value on the disease at $10^{\circ}C$, but it showed above 95% control value at the range of $30-35^{\circ}C$. It was confirmed that the control effect of seed disinfectants increased with increasing water temperature. Meanwhile soaking period of rice seeds in the suspension of seed disinfectants and chemical dosage had no high relation to control the disease. This results suggest that rice varieties, water temperature, and optimal selection of suitable seed disinfectants are very important to control Bakanae disease effectively.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.32-32
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• 2022

Abaca (Musa textilis L. Nee) is a native Musa species from the Philippines known for its natural fiber. Abaca fiber a.k.a. Manila hemp extracted from its pseudostems is considered one of the strongest fibers in the world. This is used for commodities such as ropes, papers, and money bills. Abaca is vulnerable to pests and diseases such as the Abaca Bunchy Top Disease (ABTD) caused by Abaca Bunchy Top Virus (ABTV) and Banana Bunchy Top Virus (BBTV). Inosa, one of the varieties of abaca utilized in the Philippines, is highly susceptible to ABTD. In contrast, Pacol (Musa balbisiana L.), a close relative of abaca, is highly resistant to the same disease. Here, we report the sequencing and de novo genome assembly of both abaca var. Inosa and banana var. Pacol. A total of ~16 Gb and ~21 Gb raw reads for Inosa and Pacol, respectively, were generated using Pacbio Hifi sequencing method and assembled with Hifiasm. High-quality de novo assemblies of both Musa species with 99% recovered as per BUSCO analysis were obtained. The assembled Inosa genome has a total length of ~654 Mb and N50 of 7 Mb while Pacol has a total length of 527 Mb and N50 of 3 Mb which are close to their estimated genome size of ~638 Mb and ~503 Mb, respectively. The information that can be derived from the de novo assembled genomes would provide a solid foundation for further research in disease resistance and fiber quality improvement in abaca.

• Korean Journal of Organic Agriculture
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• v.19 no.3
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• pp.357-372
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• 2011

We carried out the experiment to select the suitable sprout soybean varieties for environment-friendly cultivation in paddy field of southern part area, compares of excess moisture injury degree and yield ability among 29 sprout soybean varieties. Plant growth of sprout soybean was generally low in beginning and recovered after flowering due to rainfall. In paddy field cultivation, number of pod per individual and number of seed per individual were less in difference than upland cultivation, and maturing date was delayed 5-14 days than upland cultivation in most species. When environment-friendly cultivation, pest injury was not caused major problem for the growth during the vegetative period of soybean due to ground spider as natural enemy to insect pest. However, damage of stink bugs showed severe during grain filling period, and Dawonkong, Anpyeongkong, Dachaekong and Wonhwangkong showed susceptible to sting bug. SMV infection was weak and showed some necrosis symptoms in Sokangkong, but black root rot was not infected at all. Bacterial pustule began to be infected slowly from pod enlargement stage in most species, displayed severe symptoms in Dawonkong, Pungsannamulkong, Seonamkong and Sobaeknamulkong. The symptoms of pod anthracnose, pod blight and purple spot were greatly appeared after flowering. Disease resistance varieties was Paldokong, Kwangankong, Doremikong, Somyeongkong, Pungsannamulkong, Iksa-namulkong, Seonamkong, Sojinkong, Pureunkong, Bosugkong, Namhaekong and Sorokkong. Lodging index showed 3 in Saebyeolkong, and other species displayed slight lodging in 0-3 degree. 100-seed weight is 9.8-17.2g extent and increased 0.1-3.7g than upland cultivation in most species, but decreased in some species. Government purchase standard, species correspond to small-seed-size namulkong (Sizing screen diameter 4.0-5.6 mm) was Dawonkong, Dachaekong, Bosugkong, Seonamkong, Sokangkong, Hannamkong, Somyeongkong and Wonhwangkong. Species which seed yield was higher than Pungsannamulkong (266kg/10a) were Sorokkong, Hannamkong, Bosugkong and Sowonkong. Considering sprout soybean species, disease endurance, insect resistance, lodging resistance, 100-seed weight, yield ability and excess moisture tolerances synthetically, Seonamkong, Hannamkong, Doremikong, Bosugkong, Pungwonkong, Kwangankong, Sowonkong, Dagikong, Paldokong, Eunhakong and Pungsannamulkong were promising for environment-friendly cultivation in paddy field.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.15
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• pp.85-97
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• 1974

In order to clarify the inducing conditions and cause of sterility in rice plants, 4 varieties were cooled at 3 different levels of temperature combined with 3 different levels of treatment period. And 19 varieties were tested to examine the varietal difference of cold resistance. The results obtained were summarized as follows; 1. There were significant varietal differences in the effect of cooling treatment at meiotic stage. Suwon 213-1 was induced heavy sterility by 3 day cooling treatment at 17.5$^{\circ}C$ whereas Hayayuki, Nongpaik and Jinheung were induced a little sterility by 3 day cooling treatment at 15$^{\circ}C$ and 5 day treatment at 17.5$^{\circ}C$. The per cent of grain fertility was correlated significantly with the delayed days to heading, the degree of panicle extraction (Suwon 213-1, Nongpaik, Jinheung), culm length (Nongpaik, Suwon 213-1), and Auricle distance (Suwon 213-1). The degree of sterility was able to be estimated from the linear regression equation between the degree of panicle extraction (distance from panicle neck to flag leaf) and fertility percentage. In the case of heavy cold damage by the treatment of low temperature at meiotic stage, the rice plant had somewhat lower pollen density per anther, small and ununiform anther and pollen in size, and more sterile pollen grains. Suwon 213-1 showed anthesis in almost all spikelets, while Nongpaik, Jinheung and Hayayuki indicated considerable number of indehisced anther at 5 days after heading. 2. The fertility were not generally higher in cooling treatment at heading stage than at meiotic stage treatment. And significant correlation was found between the percentage of grain fertility treated at above two stages. Nongpaik and Jinheung were not affected in percentage of fertility by 5 day treatment at 15$^{\circ}C$ when these were treated at heading stage. Indehisced anthers were not found in Suwon 213-1 and Hayayuki, but Nongpaik and Jinheung showed more anthers which did not show anthesis 3. There was different varietal response to low temperature which was indicated by the decrease of grain fertility resulted from cooling treatment at meiotic stage. Jaekeun and Jinheung did not show low fertility but Milseong, Suwon 210, Satominoli and Suwon 213-1 showed outstanding decrease in fertility percentage by the cooling treatment at meiotic stage. The varieties which had low fertility were likely to have low pollen density per anther, abnormal anthers, small size po]]en grains and many sterile pollens. 4. Remarkable varietal difference of cold resistance was found in heading stage cooling treatment. Nongpaik, Jinheung, Jaekeun, Paltal, Akibare, Milseung and Palkeong were not affected in grain fertility by cooling treatments but Nonglimna No. 1, Suseong, Hayayuki, Suwon 213-1 and Suwon 210 showed significantly high sterility as treated by cool temperature. Most of the varieties showed higher fertility by cooling treatment at heading stage than meiotic stage but Hayayuki, Suseong and Nonglimna No.1 showed lower fertility when these were treated at heading stage than meiotic stage. There were two grops of varieties in the response to cooling treatment, one was somewhat non-anthesised and the other showed full anthesis. 5. In cold injury test of young seedlings, the result of observation was not accorded with the degree of growth inhibition. As a general, Palkeum and Suseong were highly torelant to cool temperature but Suwon 213-1, Jaekeun, Paltal, Shirogane, Palkeong, Mankyung were highly susceptible. 6. There is no significant correlation between the degree of young seedling cold damage and or the degree of growth retardation at seedling stage and grain fertility resulted from coding treatment both heading and meiotic stage.

• Korean Journal of Agricultural Science
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• v.4 no.2
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• pp.283-316
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• 1977

In an attempt to obtain a basic information to develop an effective integrated system of controlling sheath blight of rice in Korea, the transition of this disease, the variation of cultural characters and pathogenicity of the pathogen, environmental conditions affecting the disease outbreak and varietal resistance have been investigated. 1. Rice sheath blight which has been minor disease in the past was widely spread, especially since 1971. This disease has promptly spread all over the country and infected 65.2% of total rice growing area in 1976. Various factors are considered to be related to such transition of this disease. Above all, increace of application of nitrogenous fertilizer, early season and earlier cultivation of rice, introduction of more susceptible "Tongil" varieties etc. must be important factors influencing the outbreak of this disease. 2. Great variations in cultural characteristics-such as mycelial growth rate, color of the medium, amount of the aerial mycelium, shape and color of the sclerotia- and in the pathogenicity of isolates of the pathogen, Thanatephorus cucumeris Dank were observed. The optimum temperature for mycelial growth also varied with isolates, from $25^{\circ}C$ to $30^{\circ}C$. There were not necessarily any correlation between curtural characteristics and pathogenicity of isolates of Thanatephorus cucumens. 3. Mycelial grow th of isolates of Thanatephorus cucumens on the PDA medium were correlated with the air temperatures of the region where the isolates were collected. The isolates from the regions with high temperature grew well on PDA medium at $35^{\circ}C$ than those from the region with low temperature, on the other hand, the isolates from the regions with the low temperature grew well on the same medium at $12^{\circ}C$ than those from the regions with high temperature. 4. Pectin polygalacturonase (PG) and cellulase (Cx) were most active on the 3rd day after inoculation on the leaves of rice plant with Thanatephorus cucumeris, whereas pectin methylestrase (PE) was most active on the 4th day after inoculation. Relationship between the activities of PE of isolates and the strength of pathogenicity of isolates was obtained, but PG and cellulase activities were not correlated with pathogenicity of isolates. 5. The tolerence of sclerotia from in-vitro culture to low temperature varied with their water content, the dried cultural sclerotia were more tolerent than wet ones, Dried cultural sclerotia maintained almost 100% germinability for 45 days at $-20^{\circ}C$, whereas wet sclerotia lost viability at $-5^{\circ}C$. The germination ratio of the sclerotia after overwintering changed from 18% to 70% according to the water content of the test paddy fields and the ratio was low in wet paddy condition. 6. To investigate the host range of this fungi in and near paddy field, 17 weeds were inoculated with fungi. The lesions of sheath blight disease was obserbed on Sagittaria trifolia L., Echinochloa crusgalli P. Beauv., Monochoria vaginal is Presl, Polygonum Hydropiper L., Eclipta prostrata L., Digitaria sanguinalis Scapoli. 7. When the level of nitrogen applied was doubled over standard level, total nitrogen content in rice sheath increased, ami when silicate was applied, starch content in rice sheath decreased, inducing the rice plants more susceptible to sheath blight disease. Increased dressing of potash ferilizer reduced the incidence of sheat blight disease. 8. The percentage of infected stems in the early period increased more in the narrow hill plot than in the wide hill plot, but in the late period this tendency was inversed; the percentage of infected stems as well as severity in the wide hill plot increased more compared to the narrow hill plot, and the disease severity in the one plant per hill plot was also low. The number of stems in the wide hill plot was more than the number of stems in the narrow hill plot. This indicates that the microclimate, such as the relative humidity, in the narrow hill plot was more favorable for the development of this disease. 9. There was a high negative correlation between the disease severity of varieties to the sheath blight and the maturity of the varieties, that is, the early varieties were more susceptible than the late ones, and much-tillering varieties usually showed more infection than less tillering varieties. 10. No relationship was obtained between the percentage of infected stems in the early period and the severity after heading, whereas a distinct relationship was obtained between former and latter after Aug. 10.

• Korean journal of applied entomology
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• v.25 no.1 s.66
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• pp.53-61
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• 1986

The races of soybean cyst nematode, Heterodera glycines were investigated at 13 localities in Kyungpook, Chungpook and Cheonnam provinces for the resistant soybean variety selection to soybean cyst nematode. Race C, 1, and 5 were distributed and among them race 5 was dominant in Korea. Native soybean 203 lines and 25 introduced soybean varieties were investigated in field where soybean cyst nematode race 5 infested. As the result, the reproduction of soybean cyst nematode in native soybean lines decreased on entry number 18, 21, 36, 38, 41, 42, 43, 45, 55, 59, 68, 72, 75, 93, 94, 95, 98, 123, 131, 136, 146, 170, 174, 187, 190, 191 than others. And then, in pot experiment, entry number 170 showed moderately resistant with 10 cysts per root, while entry number 55 was decreased reproduction a little and the other 25 line appeared susceptibility. In introduced soybean varieties, Peking, Illsoy and PI90763 showed resistance and not reproduction in field and pot experiment. But Custer, Delmar, Dyer and Jackson represented moderately resistant under 10 cysts, while the other 18 varieties were susceptible. In yield analysis, native soybean line 170 showed the same tendency as Peking and PI90763 known for resistant varieties in decreased rate of branch number, pod number, pod weight per plant and weight of 100 grains. Peking and PI90763 decreased at the rate of under 1.6% in branch number, pod number, pod weight per plant and weight of 100 grains, while Illsoy showed a little higher decreased rate of 3.8% in pod number and 3.4% in pod weight per plant. Custer, Delmar, Dyer and Jackson represented a little higher decreased rate in yield.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.4
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• pp.314-326
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• 2020

This study was carried out to develop a resistant variety against the K3a race of bacterial blight, Xanthomonas oryzae pv. oryzae, through expansion and pyramiding of resistance genes. To develop an elite bacterial blight-resistant cultivar, the breeding process and bacterial blight resistance reactions in advanced backcross lines (ABLs) were analyzed. ABLs21 which contain Xa3 and Xa21, were developed by double backcrossing japonica cultivar Hwanggeumnuri, which has bacterial blight resistant Xa3 gene, and indica variety IRBB21, which havs Xa21 gene, followed by disease resistance bioassay and marker-assisted selection. The resistance genes of ABLs21 were amplified by PCR with the molecular markers 9643.T4 (Xa3) and U1/I1 (Xa21). Hwanggeumnuri and IRBB3 showed resistance reactions against K1, K2, and K3 races, and a susceptible reaction against K3a, K4, and K5 races. IRBB21 showed resistance reactions against K2, K3, K3a, K4 and K5 races, and a susceptible reaction against K1 race. Hwanggeumnuri showed susceptible reactions at the seedling, tillering and adult stages (all stages), whereas ABL21-1 showed moderate resistance at the tillering stage. ABL21-1 showed stable resistance against 18 isolates of K3a race, and the lesion length was shorter than that of the donor parents. In cluster analysis, the HB4032 isolate showed the highest pathogenicity among the 18 isolates. The molecular marker polymorphisms and average substituted chromosome segment lengths of ABLs21 were 63.2 % and 86.1 cM, respectively. Insertion of the donor chromosomal segments occurred in the predicted region of the Xa21 gene of ABLs21.

• Korean Journal of Breeding Science
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• v.50 no.4
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• pp.387-395
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• 2018

This study was conducted to identify DNA markers related to resistance to herbicide containing mesotrione in Tongil type rice. Two Tongil type elite lines; Milyang154 and Suweon382, showed resistance to mesotrione, whereas the others were susceptible at 20 days after mesotrione application, and severe growth inhibition was observed in the remaining 13 lines. As a result of analysis of mesotrione resistance using 190 $F_2$ populations derived from a cross of Hanareum2 (susceptible) and Milyang154 (resistant), the mesotrione resistance locus was shown to be a single dominant gene with a 3:1 segregation ratio ($X^2=1.19$, P=0.31). To identify a DNA marker closely linked to the mesotrione resistance gene, bulked segregant analysis (BSA) was adopted. The DNA marker RM3501 was identified on chromosome 2 with a recombinant value of 0.53 to the mesotrione resistance gene. Mst1(t) was located between SSR (simple sequence repeat) markers RM3501 and RM324 with a physical map distance of 10.2 Mb-11.4 Mb on chromosome 2. The band pattern of agarose gel electrophoresis of the SSR marker RM3501 showed the same segregation pattern with respect to mesotrione treatment in 20 Tongil type varieties and a $BC_2F_2$ segregation population derived from a cross between Unkwang (resistant) and Hanareum2 (susceptible). Thus, the RM3501 DNA marker could be used in breeding programs for Marker Assisted Selection in mesotrione resistant rice breeding.

• Molecules and Cells
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• v.25 no.3
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• pp.407-416
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• 2008

Thirteen near-isogenic lines (NILs) of japonica rice were developed via a backcross method using the recurrent parent Chucheong, which is of good eating quality but is susceptible to Magnaporthe grisea, and three blast resistant japonica donors, Seolak, Daeseong and Bongkwang. The agro-morphological traits of these NILs, such as heading date, culm length, and panicle length, were similar to those of Chucheong. In a genome-wide scan using 158 SSR markers, chromosome segments of Chucheong were identified in most polymorphic regions of the 13 NIL plants, and only a few chromosome segments were found to have been substituted by donor alleles. The genetic similarities of the 13 NILs to the recurrent parent Chucheong averaged 0.961, with a range of 0.932-0.984. Analysis of 13 major blast resistance (R) genes in these lines using specific DNA markers showed that each NIL appeared to contain some combination of the four R genes, Pib, Pii, Pik-m and Pita-2, with the first three genes being present in each line. Screening of nine M. grisea isolates revealed that one NIL M7 was resistant to all nine isolates; the remaining NILs were each resistant to between three and seven isolates, except for NIL M106, which was resistant to only two isolates. In a blast nursery experiment, all the NILs proved to be more resistant than Chucheong. These newly developed NILs have potential as commercial rice varieties because of their increased resistance to M. grisea combined with the desirable agronomic traits of Chucheong. They also provide material for studying the genetic basis of blast resistance.

• Research in Plant Disease
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• v.18 no.2
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• pp.86-92
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• 2012

Clubroot caused by Plasmodiophora brassicae Woron. is one of the most important diseases in Brassica crops worldwide. To establish more simple and reliable screening method for resistant cabbage and broccoli to P. brassicae, the development of clubroot on the plants according to inoculum concentration and incubation period after inoculating with the pathogen was investigated using P. brassicae GN1 isolate (race 9). To facilitate and acquire precise result of resistance screening of cabbage and broccoli to clubroot, 14-day-old seedlings were inoculated by drenching roots with the spore suspension of P. brassicae to give inoculum density of $2.5{\times}10^9$ spores/pot. To develop the disease, the inoculated seedlings were incubated in a growth chamber at $20^{\circ}C$ for 3 days, and then cultivated in a greenhouse ($20{\pm}5^{\circ}C$) for five weeks. Under the optimum conditions, 16 cabbage and 17 broccoli cultivars were tested for resistance to four field isolates (GN1, GN2, GS and YC) of P. brassicae collected from four regions in Korea. Among them, some cabbage and broccoli cultivars showed different resistance response to three isolates (GN1, GN2 and GS) determined as race 9 by using the differential varieties of Williams. On the other hand, all the tested cultivars were highly susceptible to YC isolate (race 2). The results suggest that this method is efficient screening method of cabbage and broccoli for resistance to P. brassicae.