• Journal of Korean Society of Forest Science
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• v.85 no.1
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• pp.96-106
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• 1996

Red alder(Alnus rubra Bong.) seedlings inoculated with Frankia only or both Frankia and spores of Alpova diplophloeus(Zeller & Dodge) Trappe & Smith were grown in a greenhouse for ten weeks. The ten-week-old seedlings were fertilized with six nitrogen(N) and phosphorus(P) fertility regimes (no fertilization, 10mM $NH_4NO_3$, 50mM $NH_4NO_3$, 5mM $KH_2PO_4$, 10mM $NH_4NO_3+5mM$ $KH_2PO_4$, and 50mM $NH_4NO_3+5mM$ $KH_2PO_4$) three times a week for ten weeks. The higher N-fertilization significantly increased mycorrhiza formation by greenhouse contaminant mycorrhizal fungi, but decreased N-fixation and P concentration in nodule tissues. P-fertilization significantly increased nodule and shoot dry weight, and P concentration in plant tissues. When N was highly fertilized, however, the P-fertilization effect disappeared in nodule P concentration but doubled in leaf P concentration. A. diplophloeus inoculation significantly increased diameter growth and $CO_2$ exchange rate, but decreased leaf dry weight. Our results suggest that the higher N- or P-fertilization affect nitrogenase activity and mycorrhizal development but the effects are changed by their interactions.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.126-126
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• 2003

Incidence of crown gall on lower stem of chrysanthemum, Chrysanthemum morifolium Ramat., was first observed at Hwasung, Gyeonggi, Korea in 2001, Tumors on the stem were 1.5-2 cm in size and semi-round with rough surface texture of dark brown color. Four strains of bacteria isolated from the tumor tissues were characterized. Their colonies were convex, glistening, circular with an entire edge, and white to tannish-cream in color on PDA plus CaCO$_3$. They were gram negative, oxidase positive, and growing on DIM agar. The bacterial isolates inducing gall formation in chrysanthemum were identified as Agrobacterium tumefaciens based on biochemical and physiological characteristics, fatty acid profile using Sherlock Microbial Identification System, and substrate utilization patterns using Biolog Identification System. Young chrysanthemum plants inoculated with the bacteria developed typical galls within two to three weeks. Seedlings of tomato and slices of carrot roots also produced typical galls two to three weeks after inoculation. This is the first report on crown gall of chrysanthemum in Korea.

• Korean Journal of Microbiology
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• v.30 no.6
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• pp.450-455
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• 1992

Five strains of the fast-growing endosymbionts were isolated from the nodules of Lotus eorniculatus var. japonicus inhabited in Taejeon. From morphological and physiOlogical characteristics and nodulation test, the isolated strains were identified as Rhizobium loti. Compared to the control plant, both Lotus cornieulatus var. japonieus and Lotus corniculatus seedlings inoculated with the isolated strains. grew normally due to effective root nodule. The reisolated endosymbiont from the induced root nodule was confirmed identical to those of the first isolates by investigating antibiotic resistance and morphological characteristics. Three strains among the isolates. R. loti TUS I. TUS5 and TUS6 produced a ca1cof1uorbinding exopolysaccharide.

• Journal of Forest and Environmental Science
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• v.34 no.5
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• pp.388-394
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• 2018

An efficient and reproducible protocol for in vitro germination of seeds of Couroupita guianensis has been developed in the present study. Couroupita guianensis is a medicinally important tree and categorized as threatened plant species by the IUCN. The seeds were surface sterilized using 0.1% $HgCl_2$ and inoculated on MS (Murashige and Skoog) and Woody Plants (Llyod and McCown) medium. The seeds with partially removed seed coat responded better (100%) on half strength MS medium as compared to the full (51%), one-fourth strength MS (79%) and the WP medium. Half strength MS medium conjunct with $2.0mg{\cdot}L^{-1}$ indole-3 butyric acid (IBA) was found best among the different types of auxins and cytokinins tested for seed germination, as all the seeds germinated on this medium combination. The seedlings were successfully hardened in the greenhouse and restored in the field with 83% survival rate. The protocol can be used as conservation measure for large scale multiplication of this threatened forest tree species.

• The Plant Pathology Journal
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• v.17 no.3
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• pp.154-158
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• 2001

A severe root rot of kiwifruit caused by a species of Phytophthora occurred in 1-to 5-year-old vines at the south coast region of Korea in 1997. Infected vines exhibited leaf chlorosis, scorch and defoliation, root and stem rot, and eventual death. The disease was relatively severe in poorly drained lowlands, of which 19 out of 23 fields were damaged by the disease. Meanwhile, only one among 58 upland fields was infected by the disease. Incidence of infected vines reached over 80% in heavily damaged fields and a species of Phytophthora was isolated from inner tissues of roots, stems, and rhizosphere soils of the plants. The causal pathogen was identified as P. drechsleri based on its mycological characteristics. Pathogenicity of the fungus was confirmed by artificial inoculation to seedlings of kiwifruit 'Hayward'. The pathogen was re-isolated from the inoculated plants showing symptoms similar to those observed in the fields. Root rot of kiwifruit caused by P. drechsleri has not been reported previously in Korea.

• Research in Plant Disease
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• v.8 no.1
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• pp.45-49
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• 2002

Seasonal occurrence of strawberry anthracnose in greenhouses caused by Colletotrichum sp. was examined from 1997 through 1999 at three locations, Kyeongju, Goryeong, and Cheongdo in Kyungbuk province, Korea. Also some factors related to the anthracnose infection such as initial infection sites, inoculation methods, and soil nature were studied through in vitro and field experiments. The anthracnose disease begun to occur from 15 days after transplanting in early October, and continued but gradually decreased thereafter for 2 months until December, After transplanting, initial infection mainly occurred through the runner of which the tissue was more susceptible to the anthracnose than those of the leaf and petiole when the fungal mycelial disk was inoculated. Postplanting inoculation by irrigation with spore suspension was much more effective in inducing the anthracnose disease than preplanting soil mix. However without inoculation, no or little anthracnose occurred regardless of commercial, non-cultivated or diseased field soils when healthy seedlings were planted. This suggests that occurrence of strawberry anthracnose in fields may be related to contamination of plant propagules with the anthracnose pathogen.

• The Plant Pathology Journal
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• v.29 no.1
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• pp.87-92
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• 2013

This study was conducted to determine the Phytophthora rot resistance of 514 accessions of watermelon germplasm, Citrullus lanatus var lanatus. About 46% of the 514 accessions tested were collections from Uzbekistan, Turkey, China, U.S.A., and Ukraine. Phytophthora capsici was inoculated to 45-day-old watermelon seedlings by drenching with 5 ml of sporangial suspension ($10^6$ sporangia/ml). At 7 days after inoculation, 21 accessions showed no disease symptoms while 291 accessions of susceptible watermelon germplasm showed more than 60.1% disease severity. A total of 510 accessions of watermelon germplasm showed significant disease symptoms and were rated as susceptible to highly susceptible 35 days after inoculation. The highly susceptible watermelon germplasm exhibited white fungal hyphae on the lesion or damping off with water-soaked and browning symptoms. One accession (IT032840) showed moderate resistance and two accessions (IT185446 and IT187904) were resistant to P. capsici. Results suggest that these two resistant germplasm can be used as a rootstock and as a source of resistance in breeding resistant watermelon varieties against Phytophthora.

• Mycobiology
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• v.32 no.4
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• pp.149-154
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• 2004

Toxin produced by Colletotrichum falcatum Went, the incitant of red rot of sugarcane was isolated, purified and assayed to determine host specificity and identify its chemical nature. The toxin was found to be not host specific as it inhibited germination of various seeds(gram, greengram, blackgram, pea, cowpea, rice and sugarcane) as well as different seedlings viz. tomato, coriander, pea and rice. The toxin consists of two distinct fraction-one fraction having $R_f$, value at 0.36 producing identical red rot lesion when inoculated at leaf midrib of sugarcane, and the other having $R_f$, value at 0.72 not showing any red rot lesion. Chromatogram of high performance liquid chromatography(HPLC) of the red rot lesion causing fraction showed a sharp peak at 1.62 min of retention time(RT), and spectral analysis indicated the presence of following chemical $CH_3$ - groups-C-H, C=O, C-N, $-CH_3,\;-CH_2$ -CH and molecular mass of the compound was 203. - ($M^+,\;C_{11}H_{11}N_2O_2$).

• The Korean Journal of Mycology
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• v.50 no.4
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• pp.319-329
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• 2022

In July 2020, wilting symptoms were observed among adzuki bean plants (Vigna angularis var. angularis L.) in the fields in Yeosu, Korea. Infected plants showed yellowing of leaves, browning inside the stems, splitting of stem bark, and wilting. When these plants were uprooted, their roots were found to be brown. The fungal pathogens NC20-737, NC20-738, and NC20-739 were isolated from symptomatic stem and root tissues. These pathogens were identified as a Fusarium fujikuroi species complex based on their morphological characteristics. Molecular identification was performed using the DNA sequence of translation elongation factor 1 alpha and the RNA polymerase II second largest subunit regions. The nucleotide sequences of all three isolates were similar to the F. fujikuroi reference isolates NRRL 13566 and NRRL 5538 of the National Centre for Biotechnology Information GenBank. A pathogenicity test was conducted by the soil inoculation method with cornmeal sand inoculum. Approximately 3 weeks after inoculation, symptoms were observed only in the inoculated adzuki bean seedlings. To the best of our knowledge, this is the first report of Fusarium root rot caused by F. fujikuroi in adzuki beans, both in Korea and worldwide.

• Journal of Korean Society of Forest Science
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• v.77 no.4
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• pp.453-459
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• 1988

The purposes of this study were to evaluate the effects of acid rain on tree growth and on the mycorrhizal formation and the effects of mycorrhizae on the host tolerance to acid rain. Simulated acid rain was applied for five months to Pinus $rigida{\times}taeda$ seedlings in pots inoculated with Pisolithus tinctorius (Pt) and Suillus luteus (Sl). Mycelial inocula of Pt and Sl were either mixed with entire pot soil (Mix) or casted as a band (Band) after soil sterilization. Three pH levels of acid rain (pH 3.0, 4.5 and 6.4 adjusted by 3 : 1 mixture of sulfuric and nitric acids) were tested. Pt-Mix was most effective in growth stimulation and resulted in 45-90% increase in tree height in sandy loam. Pt-Band was less effective than Pt-Mix in growth stimulation and mycorrhizal formation. Simulated acid rain at pH 4.5 stimulated height growth by 10-55%, while acid rain at pH 3.0 did not significantly affect the height growth. The top/root ratio was increased by pH 4.5 treatment, while pH 3.0 treatment reduced it. Mycorrhizal infection rate was not affected by acid rain. Pt inoculation reduced acid-induced leaf injury by 28-58% in both pH 3.0 and 4.5 compared with un-inoculated plants. Sl was also effective in growth enhancement, but was less effective than Pt in both mycorrhizal infection and reducing leaf injury.