• The Plant Pathology Journal
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• v.24 no.4
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• pp.453-460
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• 2008

In the course of in vitro and in vivo screening for bioherbicidal agents, a hyphomycete fungus, Myrothecium sp. F0252 was selected as a candidate for the biocontrol of weeds. The isolate was identified as Myrothecium roridum Tode ex. Fries based on the morphological characteristics and 18S ribosomal DNA sequence analysis and registered as Myrothecium roridum F0252. In order to evaluate the in vitro effect of M. roridum F0252 on germination of ladino clover and white clover (Trifolium repens L.) seeds, spore solution of the fungus was employed in two concentrations, $6.5{\times}10^6$ and $2.5{\times}10^7$ spores per mL and then inoculated to the seeds. The fungal spores inhibited the seed germination, infected the seedlings, and caused an abnormal withering and inhibition of seedling growth. In addition, when the herbicidal activity of crude ethyl acetate extract from the liquid culture was assessed on a mini-plant, duck-weed (Lemna paucicostata (L.) Hegelm.), the extract showed high inhibitory effect at the level of $12.5{\mu}g$ per mL. On the other hand, in vivo herbicidal activity of M. roridum F0252 was evaluated by a whole plant spray method. M. roridum F0252 exhibited strong and broad-spectrum herbicidal activity. The herbicidal values ranged from 95-100% against 7 weeds, including Abutilon avicennae and Xanthium strumarium, and 70-80% against Digitaria sanguinalis and Sagittaria pygmaea. When the nutritional utilization (95 carbon sources) pattern of M. roridum F0252 was investigated, it varied with water activity ($a_w$) and temperature conditions, supplying good, basic information in regard to nutritional utilization for proper cultivation and formulation. Our results showed that M. roridum F0252 might be used as a potential biocontrol agent against weedy plants.

• Research in Plant Disease
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• v.17 no.1
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• pp.82-85
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• 2011

Bakanae disease symptom were observed in barnyard grass in paddy field in Heanam, Jeonnam. The infected plants were blighted and white mass of spore were formed on the stem. Fusarium species were isolated from infected stem and the isolates were identified as Fusarium fujikuroi based on their morphological and molecular characteristics. The isolates of F. fujikuroi were assigned to reference of F. fujikuroi among related Fusarium species based on the translation elongation factor 1-alpha gene sequence. Pathogenicity of the fungal isolates was confirmed on seedlings of rice and barnyard grass by artificial inoculation. The results indicated that barnyard grass can be inoculum source of Bakanae disease on rice. Thus, effective weed management is necessary to Bakanae disease control and healthy seed production.

• Plant Resources
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• v.5 no.1
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• pp.59-69
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• 2002

Twenty-three plants of Japanese apricot (Prunus mume) were collected from several sites around Mountains JIRI in Korea. Japanese apricots having the different morphological features were evenly distributed in the groups made from the cluster analysis, indicating no geographic distributions but artificial vegetations in Korea. Japanese apricots were, as based on the PCR-RAPD techniques, clustered into the three groups; a group (prototype) having the five white petals with the five red sepals, a group (green type) having the five white petals with the five green sepals, and a group (hybrid type) having the more than five red petals with various colored sepals. The prototype apricots showed higher toxicities than other type apricot against bacteria and production of less compounds in TLC plates. The polypetal types of Japanes apricot were related to those of p. armebiaca in the characteristics of seed (the ruggedness), but also to be closed to those of p. armebiaca in PCR-RAPD analysis. The cluster analysis of the twenty three apricots and its related species calculated from the two primers were shown to distinguish relationships of cultivars within species, or of individual plants within cultivars, but also to display the two overlapping bands resulted from PCR-RAPD technique.

• Journal of Environmental Science International
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• v.16 no.11
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• pp.1219-1223
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• 2007

The removal of nitrogen compounds from a wastewater is essential and it is often accomplished by bio-logical process. An aerobic nitrate-removing bacterium was isolated from a municipal sewage treatment plant and soil. On the basis of its morphological, cultural and physiological characteristics and 16S rRNA sequencing data, this strain was identified as Pseudomonas fluorescens, and named as P. fluorescens K4. The optimal conditions of the initial pH and temperature of media for its growth were $7.0{\sim}8.0$ and $30^{\circ}C$, respectively. P. fluorescens K4 was able to remove 99.9% of nitrate after 24 h in a culture. The strain could grow with a nitrate concentration up to 800 mg/l and was able to remove 99.9% of nitrate after 104 h of incubation. The optimal electron donor was sodium citrate for a nitrate removal. The strain K4 showed a capability of a complete nitrate removal when the initial C/N ratio was 1.0. An effect of the initial seed concentration was observed for a cell of 10% (v/v) for a nitrate removal. Especially P. fluorescens K4 could completely remove 200 mg/l ammonium for 3 days.

• Journal of Radiation Industry
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• v.5 no.1
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• pp.7-13
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• 2011

The present study has been performed to compare the physiological analysis of monocot model plant (rice) in response to ionizing irradiations (cosmic-ray, gamma-ray, and Ion beam). Ionizing radiations were implanted into monocot model plant (rice) seed. After irradiation, the seeds were planted in the plastic pots for a growth period of one month. Thereafter, the morphological and physiological characteristics including malondealdehyde (MDA) and chlorophyll content, activities of antioxidant enzymes in irradiation samples were investigated. We are confirmed that the activity level of MDA and chlorophyll content were not changed by ionizing irradiation samples. However, the free radical contents were increased in all irradiated plants. And the activities of SOD, POD, and APX were significantly increased by irradiation compared with non-irradiation plant.

• Korean Journal of Breeding Science
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• v.41 no.2
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• pp.92-100
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• 2009

To investigate the mutagenecity of sodium azide (SA) and to select mutants having various agronomic characteristics in rice (Oryza sativa L. ssp. japonica), dry seeds of rice variety 'Suweon 472' were treated with 0, 0.5, 1.0, 2.0, and 4.0 mM SA solutions prepared in 0.1 M phosphate buffer (pH 3.0). Germination rate, seedling height and sterility were investigated in $M_1$ generation and chlorophyll mutations were observed in $M_3$ generation. Germination rate and seedling height decreased as the increase of SA concentration in $M_1$ generation, the maximum seed sterility (40.8%) was found at 4.0 mM SA concentration. Chlorophyll mutants were occurred in $M_3$ generation and the frequency calculated on a line basis was 13.5% at the same treatment. Many kinds of mutations for morphological and agronomic characters were observed and mutations with short culm and glabrous leaf were frequently found in $M_3$ generation. Interestingly, five mutant lines resistant to blast or bacterial blight (BB) were selected and evaluated with several isolates in $M_3$ generation although Suweon 472 has been known to be susceptible to blast and BB. These mutants showed all resistance to seven isolates of blast and a total of 76 lines among 2,567 lines evaluated showed resistant to race K1 of bacterial blight. Two mutant lines (440172 and 41272) showed different reaction to BB isolates from the other resistant mutants. A few kinds of endosperm mutants were also identified and most of them were waxy mutants.

• Research in Plant Disease
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• v.24 no.4
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• pp.321-327
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• 2018

In 2018, symptoms of black rot on apple (Malus pumila var. dulcissima KOIDZ) cv. Fuji were observed in Yeongcheon-si, Korea. The fruit decay symptoms consisted of purple pimples spots, black rot around the seed cavity (calyx end), mummified fruit. To isolate the causal agent, small fragment (2 to 3 mm) of decayed tissue from the lesion margin were placed on WA or PDA. Fungal colonies on PDA produced dense white aerial mycelium, becoming dark gray with age. Pycnidia and conidia were observed under a light microscopy. The shapes of conidia were aseptate, ovoid, rounded at both ends, and $21.7-28.3{\times}9.9-15.3{\mu}m$. Based on morphological and cultural characteristics, this fungus was identified as Diplodia seriata. To confirm its identity, two loci (ITS and ${\beta}$-tubulin) were sequenced for molecular identification. BLAST searches indicated 100% identity with D. seriata. A pathogenicity test was conducted with isolates on Fuji apples. The apples were inoculated with mycelial plugs (5 mm) from 7-day-old cultures of the putative pathogens. All inoculated apples developed rot symptoms identical to the original symptoms, from which D. seriata were reisolated, fulfilling Koch's postulates. This study is the first report of black rot caused Diplodia seriata on apple.

• Journal of Korean Society of Forest Science
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• v.34 no.1
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• pp.1-14
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• 1977

These studies were carried out to know the variation of morphological tree forms, needles, cotyledons, seed characters and top height growth of seedlings of Pinus koraiensis S. et Z. by populations in Mt. Jiri. The results are summarized as follows: 1. It was observed that the characteristics of length, needles of serration density of needles, percentage of full seeds length, of seeds, thickness, of seeds length of cotyledons, width of cotyledon, numbers of the stomata line in cotyledons and the top height growth of seedlings were significantly different in individual trees and populations. 2. The characteristics of branch angle specific gravity of wood and resin canal numbers of cotyledons were significantly different in populations. 3. It was that the characteristics of numbers of stomata line, width, of seeds weight, of seeds serration density of cotyledons, numbers of cotyledons were significantly different in individuals. 4. The resin canals of needles showed three principle resin canals in individual trees and population, and the coefficients of variation were not shown in individual trees and populations. Stem forms showed to be a straight form with all populations. 5. The characteristics of cotyledons had generally higher tendency than the characteristics of needles in comparison with coefficience of variation.

• Korean Journal of Environment and Ecology
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• v.26 no.3
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• pp.362-366
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• 2012

To explore on the defense strategies against hervivory of five Viburnum species, morphological characteristics of the leaf, leaf domatia structure and the number, herbivores insects and mites on the leaves, collected from the trees growing in Wonju-si, Pyeungchang-gun, Taebaek-si, Taean-gun, Bonghwa-gun, Sancheung-gun and Jinju-si were investigated from May 2009 to October 2011. Domatia of V. carlesii reveals pocket type, these of V. burejaeticum, V. dilatatum and V. wrightii reveal tuft type, and that of V. odoratissimum var. awabuki reveals pouch type. Domatia number per leaf proves the highest figures, 24.0/leaf for V. burejaeticum, and the lowest, 4.9/leaf for V. carlesii. Leaf surface trichomes of four Viburnum species except for V. odoratissimum var. awabuki are mainly stellate and hispid on the leaf-blade and veins, and dense stellate trichomes on the upper leaf surface of V. carlesii, V. burejaeticum, and V. dilatatum are observed till late growing season. Extrafloral nectaries(EFN) on the terminal veins of five Viburnum species are observed. Pellucid dots on the lower leaf surface of V. dilatatum and V. wrightii might be a good defense strategies against herbivores. We observe many predatory mites eating nectar on large pellucid dots of V. dilatatum. Predatory mites number per leaf proved highly significant differences among tree species, and mean of mites number was highest values 8.1/leaf for V. burejaeticum, and the lowest 2.6/leaf for V. odoratissimum var. awabuki. These results indicate that temperate broadleave trees develop various defense strategies against herbivores for survival. The more studies on the defense strategies against herbivores of tree species might be needed for sustainable forest ecosystem.

• Journal of Plant Biotechnology
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• v.44 no.1
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• pp.35-41
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• 2017

One of the most important species, Brassica rapa encompasses a variety of commercial vegetables, such as the Chinese cabbage, pak choi and oilseed crops. The LP08 of yellow sarson (Brassica rapa ssp, tricolaris) have a distinct morphology, with yellow seed color and a unique tetralocular ovary. LP21 of pak choi (Brassica rapa ssp, chinensis) have a dark brown seed color and bilocular ovary. In this study, we generated double haploid plants by crossing the LP08 (maternal variety) and LP21 (paternal variety), using microspore culture. A total of 66 accessions with various morphological characteristics were used for content analysis of flavonoids. The three flavonoids, quercetin, naringenin and kaempferol, showed differing contents in the two crossing parents. The Chinese cabbage type 'Chiifu' was used as the control. The highest accumulation of total flavonoids was observed in LP08. The lowest mean total flavonoids were found in 'Chiifu'. Among the 66 DH accessions, the quercetin contents of 18 accessions showed higher content than LP08. Kaempferol content was also high, and was found to be 79.7% of the total flavonoid content. Naringenin content was low at 2.8%, and was not detected in 22 accessions. Interestingly, the quercetin content positively correlated with the kaempferol content. These results can be used to identify genetic locus and genes related to useful traits. Phenotypic analysis of 66 DH accessions can further be used for natural selection of good breeding materials in B. rapa.