• Weed & Turfgrass Science
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• v.7 no.3
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• pp.219-229
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• 2018

We isolated Streptomyces scopuliridis KR-001 that produced herbicidal active metabolite(s) against several grass and broad leaf weeds. In this study, potential as natural herbicide of mutant N-29 broth filtrate of S. scopuliridis KR-001 was investigated to Ambrosia artemisiifilia in a greenhouse and field condition. The broth filtrate of mutant N-29 by foliar application showed a strong herbicidal activity to A. artemisiifilia with leaf stage in a greenhouse condition. Also, field trial of foliar application within treatment range had effectively controlled with early and middle stage of A. artemisiifilia at the natural habitats. Phytotoxic symptoms of mutant N-29 broth filtrate by foliar application were wilting and discoloration, and burn-down of leaves and finally plant death. These results suggest that mutant N-29 broth filtrate is considered possible as a natural herbicide for controlling environmentally friend to invasive alien plant such as A. artemisiifilia and may provide a new lead molecule for a more efficient herbicide.

• The Plant Pathology Journal
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• v.37 no.1
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• pp.57-71
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• 2021

Rice sheath blight (ShB), caused by Rhizoctonia solani Kühn AG1-IA, is one of the destructive rice diseases worldwide. The aims of this study were to develop biocontrol strategies focusing on field sanitation and foliar application with a biocontrol agent for ShB management. Streptomyces padanus PMS-702 showed a great antagonistic activity against R. solani. Fungichromin produced by S. padanus PMS-702, at 3.07 mg/l inhibited 50% mycelial growth, caused leakage of cytoplasm, and inhibited the formation of infection structures of R. solani. Fungichromin could reach to 802 mg/l when S. padanus PMS-702 was cultured in MACC broth for 6 days. Addition of 0.5% S. padanus PMS-702 broth into soil decreased the survival rate of the pathogen compared to the control. Soil amended with 0.5% S. padanus broth and 0.5% tea seed pomace resulted in the death of R. solani mycelia in the infested rice straws, and the germination of sclerotia was inhibited 21 days after treatment. Greenhouse trials revealed that S. padanus cultured in soybean meal-glucose (SMGC-2) medium after mixing with different surfactants could enhance its efficacy for inhibiting the pathogen. Of six surfactants tested, the addition of 2% tea saponin was the most effective in suppressing the pathogen. S. padanus broth after being fermented in SMGC-2, mixed with 2% tea saponin, diluted 100 fold, and sprayed onto rice plants significantly reduced ShB disease severity. Thus, S. padanus PMS-702 is an effective biocontrol agent. The efficacy of S. padanus PMS-702 for disease control could be improved through formulation.

• Korean Journal of Weed Science
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• v.30 no.4
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• pp.429-436
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• 2010

Herbicidal activity and characteristics of chrysophanic acid were investigated in semi-field condition. At early and middle post-emergence, Trifolium repens appeared to be very susceptible to chrysophanic acid of $2,000{\mu}g\;mL^{-1}$. However, herbicidal activity of chrysophanic acid of $2,000{\mu}g\;mL^{-1}$ estimated by visual injury to Artemisia princeps was not caused considerable phytotoxicity. Also by foliar application, the concentration of crysophanic acid for effectively control to Polygonum aviculare was much higher than $2,000{\mu}g\;mL^{-1}$. Herbicidal activity of chrysophanic acid to Echinochloa crus-galli, Cypres difformis, Setaria viridis, Digitaria sangguinalis, Bidens tripartita by foliar application was more effective at concentration ranges from 4,000 to $6,000{\mu}g\;mL^{-1}$. These results suggest that chrysophanic acid demanded for higher than $2,000{\mu}g\;mL^{-1}$ to successful weed control in the field condition.

• Weed & Turfgrass Science
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• v.6 no.3
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• pp.212-221
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• 2017

An actinomycetes isolate G-0299 obtained from a forest soil showed strong phytotoxic activity to Digitaria ciliaris. For the foliar application study, the culture filtrate of the isolate G-0299 showed strong herbicidal activity only to D. ciliaris among the 12 monocot and 5 dicot weed species. And herbicidal activity at a concentration of 500, 250, 125 and $62.5{\mu}gmL^{-1}$ of culture filtrate was 100%, 98%, 70% and 40%, respectively. Phytotoxic symptoms of the culture filtrate by foliar application were desiccation and burn-down or bleaching of leaves and finally plant death. And then the herbicidal activity was exhibited only under the light condition. Also, chlorophyll loss of D. ciliaris leaf tissues in the light condition was much higher than in the dark condition and then chlorophyll content decreased 82%, 5%, respectively. In conclusion, our results suggest that soil bacteria, isolate G-0299 could be a good candidate for new bio-herbicide and provide a new lead molecule for a more unique herbicide.

• The Plant Pathology Journal
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• v.25 no.2
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• pp.165-171
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• 2009

Biological control activity of Acremonium strictum BCP, a mycoparasite on Botrytis cinerea, was examined against six plant diseases such as rice blast, rice sheath blight, cucumber gray mold, tomato late blight, wheat leaf rust, and barley powdery mildew in growth chambers. The spore suspension of strain BCP showed strong control activities against five plant diseases except against wheat leaf rust. On the other hand, the culture filtrate of A. strictum BCP was effective in controlling only cucumber gray mold and barley powdery mildew. Further in vivo biocontrol activities of A. strictum BCP against tomato gray mold were investigated under greenhouse conditions. Control efficacy of the fungus on tomato gray mold increased in a concentration-dependent manner. Treatment of more than $1{\times}10^6$ spores/ml significantly controlled the disease both in tomato seedlings and in adult plants. The high disease control activity was obtained from protective application of the strain BCP, whereas the curative application did not control the disease. Foliar infections of B. cinerea were controlled with $1{\times}10^8$ spores/ml of A. strictum BCP applied up to 7 days before inoculation. In a commercial greenhouse, application of A. strictum BCP exhibited the similar control efficacy with fungicide procymidone (recommended rate, $500{\mu}g/ml$) against strawberry gray mold. These results indicate that A. strictum BCP could be developed as a biofungicide for Botrytis diseases under greenhouse conditions.

• Journal of Bio-Environment Control
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• v.31 no.4
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• pp.311-318
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• 2022

Salicylic acid (SA), a phenolic compound, plays a pivotal role in regulating a wide range of physiological and metabolic processes in plants such as antioxidant cellular defense, photosynthesis, and biotic and abiotic stress responses during the growth and development. We examined the effect of exogenous SA application (100 mg·L^-1) on the growth, yield, photosynthetic characteristics, lipid peroxidation, and antioxidant enzyme activity of chili pepper plants under high temperature and drought stress conditions. SA treatment induced increases of net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr) under the stress condition with the highest level after the third treatment. The contents of malondialdehyde and H₂O₂ were significantly lower in the third treatment of SA compared to the control. The activity of ascorbate peroxidase, catalase, peroxidase and superoxide dismutase, increased in treated plants by up to 247, 318, 55 and 54%, respectively compared to the nontreated control. There was no significant difference in the growth characteristics between SA-treated and nontreated plants, while the SA treatment increased marketable yield (kg/10a) by about 15% compared to the nontreated control. Taken together, these results suggest that foliar application of SA alleviates physiological damages caused by the combination of drought and heat stress, and enhances the photosynthetic capacity and antioxidant enzyme activities, thereby improving tolerance to a combination of water deficit and heat stress in chili pepper plants.

• Korean Journal of Food Science and Technology
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• v.3 no.3
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• pp.193-210
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• 1971

Reviewed biosynthetic pathways in green leaves of thiamine, riboflavin and folate as disclosed by the authors, and the regulatory systems operating on their biosynthesis and biodegradation as revealed since a potent inhibitory activity of ATP was found for the phosphatase reactions in 1965. Physiological roles of ascorbic acid in plant were evidenced by its higher content in green and flower leaves; the content in persimmon leaves for example was found ten or more times of that in citrus fruits. A close relationship existing between basic and development researches was illustrated by examples chosen from the author's researches. Examples cited were as follows; basic researches on vitamins were extended to the creation of thiamine enriched rice, to the growth promotion of rice plant by foliar application of thiamine, and to the use of ascorbic acid to prevent the appearance of beer cloudness; histological and biochemical studies on protein bodies in rice endosperm turned out amino acid enriched rice; techniques acquired in the studies on catalase were successfully employed for the utilization of single cell protein (MIPRON) for human food; conception of hybernation was led up to under-water or under-ground storage of cereal grains.

• Journal of Plant Biology
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• v.5 no.3
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• pp.6-10
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• 1962

Leaf samples, raised on the N-deficient and N-abundant sand and sprayed with varying concentration of urea, were analized for their total chlorophyll concentration. It was observed that the depression periods of the chlorophyll content appeared at first by spraying with urea; it appeared on the 3rd day in the N-deficient plots and on the 6th day in the N-abundant plots. Causes of the depression of chlorophyll may be assumed to be in an excessive urea, an accumulation of ammonia from urea absorbed, and depression of water content owing to urea application. The maximum content of the chlorophyll was shown on the 6th day in N-deficient and on the 12th day in the N-abundant plots. The young leaves activity formed the chlorophyll by urea foliar spray, compared with the mature ones. This result was consistent with previous paper.

• Applied Biological Chemistry
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• v.45 no.3
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• pp.129-133
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• 2002

Suppression of nitrate accumulation in spinach and lettuce through foliar application of chitosan formula containing micronutrients is related with the increase of the nitrate reductase (NR) activity. If NR in spinach were highly expressed to increase the assimilatory activity, nitrate content could be reduced. For this, NR cDNA was cloned from the isolated mRNAs of spinach using reverse transcriptase-PCR. Nucleotide sequence of cloned spinach NR cDNA showed highly deduced amino acid sequence identity ($71{\sim}82%$) with other known plant NR genes. Only two nucleotide-base differences were observed in the cloned NR cDNA compared with that of the published spinach NR cDNA.

• Journal of The Korean Society of Grassland and Forage Science
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• v.37 no.3
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• pp.242-247
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• 2017

Humic acid (HA) is a complex organic matter found in the environments, especially in grassland soils with a high density. The bioactivity of HA to promote plant growth depends largely on its extraction sources. The quality-control of HA and the quality improvements via an artificial synthesis are thus challenging. We recently reported that a polymeric product from fungal laccase-mediated oxidation of catechol and vanillic acid (CAVA) displays a HA-like activity to enhance seed germination and salt stress tolerance in a model plant, Arabidopsis. Here, we examined whether HA or CAVA enhances the growth of Italian ryegrass seedling. Height and fresh weight of the plant with foliar application of HA or CAVA were bigger than those with only water. Interestingly, enhanced root developments were also observed in spite of the foliar treatments of HA or CAVA. Finally, we proved that HA or CAVA promotes the regrowth of Italian ryegrass after cutting. Collectively, CAVA acts as a HA mimic in Italian ryegrass cultivation, and both as a biostimulant enhanced the early growth and regrowth after cutting of Italian ryegrass, which could improve the productivity of forage crops.