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Five isolates of Curvularia inaequalis were obtained from blighted leaves of zoysia grass. The optimal growth temperature of the pathogen was 30°C and all isolates caused foliar blighting symptoms on zoysia grass, bent grass, and bermuda grass. Phytotoxic substances were associated with pathogenicity. Two phytotoxins were isolated from liquid cultures of C. inaequalis by ethyl acetate extraction and repeated silica gel column chromatography. On the basis of mass and nuclear magnetic resonance spectral analyses, the compounds were identified as pyrenocines A and B, phytotoxins produced by Pyrenochaeta terrestris. Pyrenocine A caused leaf necrosis in a leaf-wounding bioassay and inhibited growth of all plants tested in a whole plant test. Large crab grass and fall panicum were most susceptible to pyrenocine A. Pyrenocines A and B also caused significant electrolyte leakage from leaf tissues of bermuda grass. Pyrenocine B exhibited much weaker phytotoxic activity than pyrenocine A in all bioassays performed. Both compounds caused leaf tip dieback symptoms in turf grass plants similar to symptoms observed in the field. Thus, pyrenocines A and B are thought to be involved in the development of Curvularia blight disease of turfgrasses caused by C. inaequalis.

A new pyriculol-related phytotoxin, designated as pyricuol (1), was isolated from a liquid culture of Magnaporthe grisea, the causal fungus of rice blast disease, together with two known metabolites, pyriculol (2) and dihydropyriculol. Its structure was determined on the basis of physicochemical and spectroscopic data to be 2-(3-hydroxymethyl-1,4-hexadienyl)-6-hydroxybenzaldehyde.

Artificial graphite is typically manufactured by carbonization of a shaped body of a kneaded mixture using granular cokes as a filler and pitch as a binder. It undergoes a pitch impregnation process if necessary and finally applying graphitization heat treatment. The effect of thermal oxidation in air or a CO2 atmosphere on IG-11 graphite samples is investigated in this study. The results show a localized oxidation process that progressively reveals the large coke particles with increasing level of overall weight loss in air. The surface of the graphite was peeled off and no change was found in the specific gravity after air oxidation. However, the specific gravity of graphite was continuously decreased by CO2 oxidation. The decrease in the specific gravity by CO2 oxidation was due to CO2 gas that progressed from the surface to the interior. The pore shape after CO2 oxidation differed from that under air oxidation.

citriodora oils displayed in vitro antifungal activities against four phytopathogenic fungi except for Colletotrichum gloeospori oides. The essential oil of Thymus vulgaris suppressed the mycelial growth of C. gloeosporioides, Fusarium oxysporum and Rhizoctonia solani and that of Cymbopogon citratus was active to only F. oxysporum. The chemical compositions of the five active essential oils were determined by gas chromatography-m ass spectrometry. This study sug­ gests that both E. citriodora and C. cyminum oils have a potential as antifungal preservatives for the control of storage diseases of various crops.

Oxidative stress is one of the major factors causing injury to plants exposed to environmental stress. Transgenic sweetpotato [Ipomoea batatas (L.) Lam. cv. Yulmi] plants with an enhanced tolerance to multiple environmental stresses were developed by expressing the genes of both CuZn superoxide dismutase (CuZnSOD) and ascorbate peroxidase (APX) under the control of an oxidative stress-inducible SWPA2 promoter in the chloroplasts of sweetpotato plants (referred to as SSA plants). SSA plants were successfully generated by the particle bombardment method and confirmed by PCR analysis. When leaf discs of SSA plants were subjected to 5 μM methyl viologen (MV), they showed approximately 45% less damage than non-transformed (NT) plants. When 200 μM MV was sprayed onto the whole plants, SSA plants showed a significant reduction in visible damage compared to leaves of NT plants, which were almost destroyed. The expression of the introduced CuZnSOD and APX genes in leaves of SSA plants following MV treatment was significantly induced, thereby reflecting increased levels of SOD and APX in the chloroplasts. APX activity in chloroplast fractions isolated from SSA plants was approximately 15-fold higher than that in their counterparts from NT plants. SSA plants treated with a chilling stress consisting of 4°C for 24 h exhibited an attenuated decrease in photosynthetic activity (Fv/Fm) relative to NT plants; furthermore, after 12 h of recovery following chilling, the Fv/Fm of SSA plants almost fully recovered to the initial levels, whereas NT plants remained at a lower level of Fv/Fm activity. These results suggest that SSA plants would be a useful plant crop for commercial cultivation under unfavorable growth conditions. In addition, the manipulation of the antioxidative mechanism in chloroplasts can be applied to the development of various other transgenic crops with an increased tolerance to multiple environmental stresses.

BACKGROUND: In a search for plant extracts with potent in vivo antifungal activity against various plant diseases, we found that treatment with a methanol extract of Myristica fragrans Houttyn (nutmeg) seeds reduced the development of various plant diseases. The objectives of the present study were to isolate and determine antifungal substances from My. fragrans and to evaluate their antifungal activities. RESULTS: Three antifungal lignans were isolated from the methanol extract of My. fragrans seeds and identified as erythro-austrobailignan-6 (EA6), meso-dihydroguaiaretic acid (MDA) and nectandrin-B (NB). In vitro antimicrobial activity of the three lignans varied according to compound and target species. Alternaria alternata, Colletotrichum coccodes, C. gloeosporioides, Magnaporthe grisea, Agrobacterium tumefaciens, Acidovorax konjaci and Burkholderia glumae were relatively sensitive to the three lignans. In vivo, all three compounds effectively suppressed the development of rice blast and wheat leaf rust. In addition, EA6 and NB were highly active against the development of barley powdery mildew and tomato late blight, respectively. Both MDA and NB also moderately inhibited the development of rice sheath blight. CONCLUSION: This is the first study to demonstrate the in vitro and in vivo antifungal activities of the three lignans from My. fragrans against plant pathogenic fungi. Copyright © 2007 Society of Chemical Industry

Oxidative stress is a major damaging factor for plants exposed to environmental stresses. In order to develop transgenic potato plants with enhanced tolerance to environmental stress, the genes of both Cu/Zn superoxide dismutase and ascorbate peroxidase were expressed in chloroplasts under the control of an oxidative stress-inducible SWPA2 promoter (referred to as SSA plants). SSA plants showed enhanced tolerance to 250 microM methyl viologen, and visible damage in SSA plants was one-fourth that of non-transgenic (NT) plants that were almost destroyed. In addition, when SSA plants were treated with a high temperature of 42 degrees C for 20 h, the photosynthetic activity of SSA plants decreased by only 6%, whereas that of NT plants decreased by 29%. These results suggest that the manipulation of the antioxidative mechanism of the chloroplasts may be applied in the development of industrial transgenic crop plants with increased tolerance to multiple environmental stresses.

The biological activities of an aqueous fraction extracted from Polygonatum odoratum var. pluriflorum Owhi and of l -2-azetidinecarboxylic acid (AZC), purified from the extract, on the growth of several types of algae were tested. The aqueous fraction was prepared by methanol extraction of P. odoratum var. pluriflorum rhizomes followed by reverse partitioning with butanol. The aqueous extraction inhibited growth of the green alga Chlorella vulgaris by less than 10% at a concentration of 1000 mg L −1 . However, growth of the blue-green alga Microcystis aeruginosa was inhibited by 22.0%, 67.9%, and 87.1%, respectively, at 3.1, 6.2, and 12.5 mg extract L −1 . AZC was isolated from the aqueous extract and was shown to be the major active substance inhibiting algal growth. AZC concentrations higher than 25 μM inhibited growth, while at 400 μM, growth of the green algae C . vulgaris and Scenedesmus spp. was inhibited by 71.2% and 70.4%, respectively. In contrast, growth of the blue-green algae Anabaena affinis and M. aeruginosa was inhibited at concentrations greater than 1.6 and 0.2 μM, respectively, whereas 92% control required concentrations of 6.3 and 1.6 μM, respectively. AZC also suppressed the growth of the red-tide microalga Cochlodinium polykrikoides by 86.9% and 100% at concentrations of 6.3 and 12.5 μM, respectively. Azetidine and 2-azetidinone showed little activity on the tested algae. The results demonstrate that AZC selectively inhibits algal growth at low concentrations. The green algae C . vulgaris and Scenedesmus spp. were tolerant, whereas M. aeruginosa, A . affinis , and C. polykrikoides were relatively sensitive. Thus, extract and AZC, prepared from P. odoratum rhizomes, showed a potential as natural selective algicide for the control of harmful algae in laboratory assay.

A new compound 3-(3-bromothiophen-2-yl)-5-(2,6-difluorobenzyl)oxymethyl-5-methyl-4,5-dihydroisoxazole was synthesized and the herbicidal activity was assessed under glasshouse and flooded paddy field conditions. This compound demonstrated good rice selectivity and potent herbicidal activity against annual weeds at 125 g ai ha⁻¹ under greenhouse conditions. Soil application of this compound showed the complete control of barnyardgrass to the 4th leaf stage at 250 g ai ha⁻¹. Field trials indicated that this compound, combined with pyrazosulfuron-ethyl, controlled annual and perennial weeds rapidly with good tolerance by transplanted rice seedlings from postemergence and soil application. This compound showed a low mammalian and environmental toxicity in various toxicological tests.

The effects of environmental and chemical signals on anthocyanin biosynthesis in non-chlorophyllous (white) corn leaves were investigated. Carbohydrates that caused the greatest stimulation of anthocyanin formation included fructose, glucose, and sucrose, followed by maltose, raffinose, trehalose, cellobiose, melibiose, galactose, and lactose. Sucrose enhanced the expression of anthocyanin biosynthesis genes on a transcriptional level. Carbohydrate concentration, duration of light exposure, and incubation temperature also had quantitative effects. Low temperatures stimulated anthocyanin biosynthesis whereas water stress had no effect. Abscisic acid, jasmonic acid, and ethephon also enhanced anthocyanin accumulation, although the degree of its accumulation depended on co-supplied sucrose concentrations, and was relatively lower in white tissue than in green tissue. Gibberellic acids and 6-benzylaminopurine were significantly inhibitory at the nanomolar level. Indole 3-acetic acid and salicylic acid did not influence anthocyanin synthesis in the white tissue system. Diuron inhibited its formation only in green tissue. These results indicate that the white leaf segments of corn would be good systems for research on the signal networks related to chloroplast functioning in anthocyanin biosynthesis. Additionally, this experimental system could be practical for identifying hormone-like substances, especially gibberellic acids and benzylaminopurine.

The methanol extract of stems of Catalpa ovata G Don exhibits potent in vivo antifungal activity against Magnaporthe grisea (Hebert) Barr (rice blast) on rice plants, Botrytis cinerea Pers ex Fr (tomato grey mould) and Phytophthora infestans (Mont) de Bary (tomato late blight) on tomato plants, Puccinia recondita Rob ex Desm (wheat leaf rust) on wheat plants and Blumeria graminis (DC) Speer f. sp. hordei Marchal (barley powdery mildew) on barley plants. An antifungal substance was isolated and identified as dehydro-alpha-lapachone from mass and nuclear magnetic resonance spectral data. It completely inhibited the mycelial growth of B. cinerea, Colletotrichum acutatum Simmonds, Colletotrichum gloeosporioides Simmonds, M. grisea and Pythium ultimum Trow over a range of 0.4-33.3 mg litre(-1). It also controlled the development of rice blast, tomato late blight, wheat leaf rust, barley powdery mildew and red pepper anthracnose (Colletotrichum coccodes (Wallr) S Hughes). The chemical was particularly effective in suppressing red pepper anthracnose by 95% at a concentration of 125 mg litre(-1).

The nucleotide sequence of the cucumber (Cucumis sativus L. cv. Baekmibaekdadagi) chloroplast genome was completed (DQ119058). The circular double-stranded DNA, consisting of 155,527 bp, contained a pair of inverted repeat regions (IRa and IRb) of 25,187 bp each, which were separated by small and large single copy regions of 86,879 and 18,274 bp, respectively. The presence and relative positions of 113 genes (76 peptide-encoding genes, 30 tRNA genes, four rRNA genes, and three conserved open reading frames) were identified. The major portion (55.76%) of the C. sativus chloroplast genome consisted of gene-coding regions (49.13% protein coding and 6.63% RNA regions; 27.81% LSC, 9.46% SSC and 18.49% IR regions), while intergenic spacers (including 20 introns) made up 44.24%. The overall G-C content of C. sativus chloroplast genome was 36.95%. Sixteen genes contained one intron, while two genes had two introns. The expansion/contraction manner of IR at IRb/LSC and IR/SSC border in Cucumis was similar to that of Lotus and Arabidopsis, and the manner at IRa/LSC was similar to Lotus and Nicotiana. In total, 56 simple sequence repeats (more than 10 bases) were identified in the C. sativus chloroplast genome.

A microbial community analysis of forest soil from Jindong Valley, Korea, revealed that the most abundant rRNA genes were related to Acidobacteria , a major taxon with few cultured representatives. To access the microbial genetic resources of this forest soil, metagenomic libraries were constructed in fosmids, with an average DNA insert size of more than 35 kb. We constructed 80,500 clones from Yuseong and 33,200 clones from Jindong Valley forest soils. The double-agar-layer method allowed us to select two antibacterial clones by screening the constructed libraries using Bacillus subtilis as a target organism. Several clones produced purple or brown colonies. One of the selected antibacterial clones, pJEC5, produced purple colonies. Structural analysis of the purified pigments demonstrated that the metagenomic clone produced both the pigment indirubin and its isomer, indigo blue, resulting in purple colonies. In vitro mutational and subclonal analyses revealed that two open reading frames (ORFs) are responsible for the pigment production and antibacterial activity. The ORFs encode an oxygenase-like protein and a putative transcriptional regulator. Mutations of the gene encoding the oxygenase canceled both pigment production and antibacterial activity, whereas a subclone carrying the two ORFs retained pigment production and antibacterial activity. This finding suggests that these forest soil microbial genes are responsible for producing the pigment with antibacterial activity.

Isolation of Inonotus obliquus from Betula costata in KoreaTaxonomic Study on Some Unrecorded Taxa of Korean AphyllophoralesSurveys of Host Plants of Pestalotiopsis spp. in KoreaBacillus subtilis B...

We have previously identified genes for four different protease inhibitors (PIs) that were induced upon rice blast infection in a rice blast resistant mutant SHM-11. Our expression analysis of the PIs indicated that induction of the PIs was the highest 24 hr after rice blast inoculation in the rice mutant SHM-11. Three PIs in the group of serine PIs were highly expressed while a cystein PI was weakly expressed upon rice blast inoculation. Four PIs were weakly induced 48 hr after pathogen inoculation in rice blast susceptible wild type rice plant. The simultaneous expression of three serine PIs was apparent from SHM-11 and two of them were induced in rice blast resistant Taebaegbyeo. One of them was induced in rice blast resistant Hwayeongbyeo while none of them were expressed in rice blast susceptible Nagdongbyeo and rice blast resistant Dongjinbyeo. Our results suggest that the expression of PI gene is rice cultivar specific and may be linked with the rice blast resistance in a specific rice mutant by the simultaneous expression of the PI genes.

This study investigated the physiological causes of differences in phytotoxic symptoms shown in barnyardgrass from foliar applications of the herbicides fenoxaprop-P-ethyl and cyhalofop-butyl. When these were applied to the third leaves of the whole plant, the chlorosis and desiccation in the third leaf was greater in fenoxaprop-P-ethyl than cyhalofop-butyl. However, initial growth inhibition of the fourth leaf was greater when using cyhalofop-butyl than when using fenoxaprop-P-ethyl. In the shoot regrowth test, regrowth at five days after treatment (DAT) was smaller in cyhalofop-butyl than in fenoxaprop-P-ethyl; the regrowth at 10 DAT exhibited the reverse trend. The chlorosis (decrease of chlorophylls: carotenoids ratio) in barnyardgrass leaf segments that were floated on herbicide solution was greater in the fenoxaprop-P-ethyl treatment. These results indicate that different herbicidal responses induced by the two herbicides are likely to be related to differential translocation and metabolism. The relatively light chlorosis and desiccation in treated leaves, severe cessation of initial growth (but a lower final herbicidal efficacy in the cyhalofop-butyl treatment) are probably related to its rapid translocation to the meristem region from the treated leaf, followed by faster metabolism. In contrast, the relatively greater chlorosis and desiccation compared to inhibition of initial growth in the fenoxaprop-P-ethyl treatment is likely to be related to its relatively slower translocation and metabolism in the treated leaf.

The Inhibition of AChE activity was compared between susceptible and phenthoate resistant diamondback moth (DBM) using in vitro enzyme assay and native Polyacrylamide gel electrophoresis (PAGE). Dichlorvos and carbofuran were very effective to inhibit the AChE activity from S strains with I 50 values of 0.38 and 0.21 μM, respectively. However, the AChE from R strain was much less inhibited to dichlorvos, i.e. insensitive to dichlorvos with R/S ratio of 11.4, than phosphamidon, BPMC, and carbofuran with the R/S ratio of 2.8, 4.2, and 2.5, respectively. Direct-staining of native gel revealed that the majority of AChE from S strain was quickly deactivated by 50 μM of dichlorvos that was the lowest concentration of the inhibitor in the experiment. However, the AChE activity from R strain was not fully inhibited by 500 μM of dichlorvos. This result was confirmed in the repetitive experiment with head extracts of both strains separately prepared with three replications. In the incubation of AChE with 100 μM of dichlorvos on native gel, the AChE from R strain was apparently insensitive to the inhibitor in contrast to the fully inhibited AChE from S strain.

A series of 3-chloro-2-(4-chloro-2-fluorophenyl)-4,5,6,7-tetrahydro-2H-indazole derivatives containing various substituted isoxazolinylmethoxy groups at the 5-position of the benzene ring were synthesized and their herbicidal activities assessed under greenhouse and flooded paddy conditions. Among them, compounds having a phenyl or cyano substituent at the 3-position of the 5-methyl-isoxazolin-5-yl structure demonstrated good rice selectivity and potent herbicidal activity against annual weeds at 16–63 g AI ha−1 under greenhouse conditions. Field trials indicated that these two compounds controlled a wide range of annual weeds rapidly with a good tolerance on transplanted rice seedlings by pre-emergence application. They showed a low mammalian and environmental toxicity in various toxicological tests. Copyright © 2005 Society of Chemical Industry

Three substances that show antifungal activity against Blumeria graminis f. sp. hordei were isolated from roots of Rumex crispus and identified as chrysophanol, parietin, and nepodin. The substances were tested for plant disease control activity in vivo against six plant pathogenic fungi. All specifically reduced the development of barley powdery mildew. The concentrations required for 50% disease control were 4.7 μg/ml for chrysophanol, 0.48 μg/ml for parietin, and 20 μg/ml for nepodin. These agents showed both curative and protective activity against barley powdery mildew. Chrysophanol (100 μg/ml) and nepodin (400 μg/ml) were more effective than the fungicides fenarimol (30 μg/ml) and polyoxin B (100 μg/ml), under glasshouse conditions, against cucumber powdery mildew, which is caused by Podosphaera xanthii . Parietin (30 and 10 μg/ml) reduced the development of cucumber powdery mildew as efficiently as fenarimol (30 μg/ml) and more effectively than polyoxin B (100 μg/ml).

N -[4-Chloro-2-fluoro-5-{3-(2-fluorophenyl)-5-methyl-4,5-dihydroisoxazol-5-yl-methoxy}-phenyl]-3,4,5,6-tetrahydrophthalimide (EK-5385) is an experimental substituted bicyclic herbicide. Soil-applied EK-5385 showed good rice selectivity and potent herbicidal activity on barnyardgrass ( Echinochloa crus-galli var. oryzicola ) at rates of 3.9–250 g a.i./ha. Barnyardgrass was exhibited normal growth under dark condition, however, the growth of shoot and root was severely inhibited under light condition (14/10 h of light/dark, 50 μmol/m 2 /s of photosynthetically active radiation) when treated with EK-5385, oxadiazon, and oxadiargyl. IC 50 of EK-5385 and oxadiargyl to chlorophyll loss in cucumber cotyledons was approximately 0.3 and 0.7 μM, respectively. IC 50 of EK-5385 and oxadiargyl to carotenoids loss in cucumber cotyledons was about 0.26 and 0.1 μM, respectively. IC 50 concentration of EK-5385 and oxadiargyl on Protox activity was approximately 5.5 and 8 nM, respectively. Cellular leakage occurred without lag period from cucumber leaf squares treated with 1 μM of EK-5385 and oxadiargyl under light exposure.

Methanol extracts of fresh materials of 57 plants were screened for in vivo antifungal activity against Magna-porthe grisea, Corticium sasaki, Botrytis cinerea, Phyto-phthora infestans, Puccinia recondita, and Blumeria graminis f. sp. hordei. Among them, seven plant extracts showed disease-control efficacy of more than 90％ against at least one of six plant diseases. None of the plant extracts was highly active against tomato gray mold. The methanol extracts of Chloranthus japonicus (roots) (CjR) and Paulownia coreana (stems) (PcS) displayed the highest antifungal activity; the CjR extract controlled the development of rice blast, rice sheath blight, and wheat leaf rust more than 90％, and tomato gray mold and tomato late blight more than 80％. The PcS extract displayed control values of more than 90 ％ against rice blast, wheat leaf rust, and barley powdery mildew and more than 80％ against tomato gray mold. The extract of PcS also had a curative activity against rice sheath blight and that of CjR had a little curative activity against rice blast. On the other hand, the extract of Rumex acetocella roots reduced specifically the development of barley powdery mildew. Further studies on the characterization of antifungal substances in antifungal plant extracts are underway and their disease-control efficacy should be examined under greenhouse and field conditions.

This study was conducted to discover new phytotoxins which may be used as lead molecules for the development of new herbicides. A total of 187 endophytic fungi were isolated from 11 plant species, which were collected from 8 locations in Korea. Their herbicidal activities were screened in vivo by herbicidal and duckweed bioassays after they were cultured in potato dextrose broth and rice solid media. Both fermentation broth and solid culture extract of Gliocladium catenulatum F0006 isolated from red pine (Pinus densiflora) showed 70% herbicidal activity only against cocklebur (Xanthium strumarium) out of the 10 weeds tested. Solid culture extract of F0034 isolated from arrowroot (Pueraria thunbergiana) exhibited 20 to 100% herbicidal activities against all of the weeds. Especially, shattercane (Sorghum bicolor), barnyardgrass (Echinochloa crus-galli), large crabgrass (Digitaria sanguinalis), and fall pauicum (Panicum dichtomiflorum) were sensitive to the solid culture extract of F0034. In addition, solid culture extract of F0043 isolated from red pine displayed 20% to 70% herbicidal activities only against 5 grass species, but not against 5 broad-leaf plant species. On the other hand, as the results of duckweed assay, 8 fermentation broths showed 100% growth inhibitory activity at concentrations less than 5.0% of culture supernatants and 12 solid cultures had a potent inhibitory activity against duckweed growth. A toxic metabolite was purified from the solid cultures of G. catenulatum F0006 by repeated column chromatography and bioassay. It caused a phytotoxic syndrome only on cocklebur out of the 10 weeds tested; it completely killed cocklebur seedlings at and showed 85% herbicidal activity against cocklebur at . The molecular weight of the toxic metabolite is 238 daltons and its structure determination is underway.

The inheritance of the phenthoate-selected diamondback moth (DBM) was investigated, and the cross resistance was also examined against various insecticides. The phenthoate concentration-mortality relationship between F 1 progenies (S♀ X R♂, S♂ X R♀) obtained from reciprocal crosses with the susceptible (S) and phenthoate-selected DBM strains (R) indicated the absence of sex-linked inheritance. The resistance ratios of F 1s (S♀ X R♂), F 1R (S♀ X R♂), and phenthoate-selected(R) strains were 23.8, 24.1, and 175.1, respectively. Degrees of dominance of the Fis and F 1R progenies were 0.23 and 0.45. These results suggest that the inheritance of phenthoate resistance in DBM is controlled by one or more autosomal genes in a manner of incomplete dominance. This R strain exhibited a high level of cross resistance to parathion, pyrachlofos, and phosmet with resistance ratios of 51.1, 59.9 and 72.5, respectively, and also showed medium level of cross resistance to most organophosphorus insecticides with the range of resistance ratios among 5.0 ∼ 50.0, except for acephate, demeton-S-methyl, profenofos, and pyridaphenthion showing low level of cross resistance with resistance ratios among 1.5-4.0. However, this R strain exhibited low level of cross resistance to most carbamate insecticides except BPMC showing resistance ratio of 5.3. Similar low level of cross resistance was observed from the pyrethroid and neonicotinoid insecticides with the resistance ratios among 1.2∼4.6.

Methanol extracts of fresh materials of 183 plants were screened for in vivo antifungal activity against Magnaporthe grisea, Corticium sasaki, Botrytis cinerea, Phytophthora infestans, Puccinia recondita and Erysiphe graminis f sp hordei. Among them, 33 plant extracts showed disease-control efficacy of more than 90% against at least one of six plant diseases. The methanol extracts of Achyranthes japonica (whole plant) and Rumex crispus (roots) at concentrations greater than 11 g fresh weight of plant tissue per litre of aqueous Tween 20 solution effectively controlled the development of barley powdery mildew caused by E graminis f sp hordei in an in vivo assay using plant seedlings. At a concentration of 300 g fresh weight of plant tissue per litre of Tween 20 solution, the two extracts were as efficient as the fungicide fenarimol (30 mg litre−1) and more active than the fungicide polyoxin B (100 and 33 mg litre−1) against Sphaerotheca fuliginea on cucumber plants in glasshouse trials. Copyright © 2004 Society of Chemical Industry

This study was carried out to investigate the difference in physiological processes leading to two different responses of albinism and necrosis to the phytoene desaturase inhibitor fluridone, which is dependent on the developmental state of tissue at the time of fluridone treatment. A soil-drench of fluridone solution at the 40% growth of the 3rd leaf of maize (Zea mays L.) caused the leaf to grow into a white/green mixed leaf; completely white in the basal part (W), pale green in the middle part (PG), and green in apical part of the leaf blade (G). In the PG and G, the effective quantum yield of electron transport through photosystem II (Yield) was significantly inhibited, Fv/Fm was decreased but Fo increased, hydrogen peroxide was more accumulated than untreated control, and cellular leakage was faster and more pronounced than in the white tissue (W). In the W, however, all of Fo, Fm, and Yield values were near zero due to loss of chlorophyll. Moreover, there was a relatively low content of hydrogen peroxide, slower cellular leakage and longer survival of tissue in the W. On the other hand, the level of antioxidants such as carotenoids, tocopherols, and ascorbic acid was lower in the W than untreated control. However, the specific activities of antioxidant enzymes were elevated in the W; 3.47 times in superoxide dismutase (SOD), 3.21 times in peroxidase (POD), 1.59 times in catalase and 1.21 times in glutathione reductase. In particular, SOD and POD activities had a tendency to be increased during senescence. In the kinetics experiment carried out during a senescence of the 2nd white leaf, increase of wilting and browning began to occur prior to any significant change in MDA-equivalents, and high reduction of carbohydrate contents occurred prior to increase of wilting and necrosis. Carbohydrate supplement significantly delayed the death of white leaves. Taken together, the above results indicated that in the developed tissue, whose greening has already taken place at the time of herbicide treatment, its death was related to the cell destruction by excessive oxidative stress induced through photosynthetic electron transport blockade. Conversely, in the developing or undifferentiated tissue at the time of herbicide treatment, that eventually grown into a white tissue, its death seemed to be more dependent on a loss of photosystem function followed by carbohydrate deficiency.

Gamma-ray irradiation is known to induce various mutations in plants caused by chromosome alterations. This study investigated disease responses of selected gamma-ray induced rice mutants generated from seven Japonica-type rice cultivars against three plant diseases. Among the tested 22 mutants, three gain-of-function mutants and six loss-of-function mutants against rice blast were obtained, as well as three loss-of-function mutants against bacterial leaf blight (BLB). Two of the loss-of-function mutants were susceptible to both rice blast and BLB. Gain-of-function mutation has not been frequently observed in rice plants, thus, the mutants can be used to identify loci of novel genes for the regulation of disease resistant response.

The effects of prochloraz on membrane permeability and germination of uredospores of Puccinia recondita were investigated to determine its potential mode of action on wheat leaf rust control activity. Disease control activity of ergosterol biosynthesis inhibitors (EBIs) and their activities on uredospore membrane permeability and germination were examined with wheat leaf rust pathogen, both in vitro and in vivo. While wheat leaf rust was not controlled by prochloraz, electrolytic leakage and spore germination of P. recondita uredospore was the highest with the use of prochloraz among the eight fungicides tested. Prochloraz stimulated uredospore of P. recondita to germinate at a higher ratio. Although certain EBIs, such as hexaconazole, showed excellent control activity, their effects on uredospore membrane permeability and germination was much inferior to prochloraz. Therefore, results of this study suggest that effects of EBIs on membrane permeability and germination of uredospore are not always correlated with their disease control activity.

This study was carried out to establish a novel bioassay system for screening of compounds affecting aromatic amino acid or anthocyanin biosynthesis through investigating a degree of sucrose-induced anthocyanin formation such as size of plant material, buffer conditions, light intensity and irradiated duration, incubation temp., etc were determined and standard procedure (suitable experimental condition) was set up as follows. The second leaf blade of white corn seeding induced by fluridone treatment were segmented into a size of 55 min. The segments were floated on the solution of 1% sucrose in 1.0mM MES buffer (pH6.0∼6.5) and incubated at 26 for 2days under the continuous light condition(70∼100mol m s ). Anthocyanin in the purpled tissues was extracted with methanol containing 1% HCl and the optical density of the clear supematants was determined at 528mm. Influences of some chemicals were tested using this system. Glyphosate, 5-enolpyruvylshikimate 3-phosphate synthase inhibitor, showed most sensitive response with I value at 3.3M. Dicyclohexylcarbodiimide(DCCD) and parachloromercuribenzenesulfonic acid(PCMBS) had a relatively strong ingibition with I50 value at 7.1M and 10.2M, respectively. These results show that sucrose-induced anthocyanin formation in white com leaf segment provide a very simple and rapid system for searching new compounds affecting aromatic amino acid or anteocyanin biosynthesis by screening at less than 10M.

In 1998, a pathogen isolated from infected onions was identified as Aspergillus niger. At 3, A. niger AnYD-1 showed the best mycelial growth, spore germination, and high pathogenicity to onions. In spite of the weak inhibitory effect of flusilazole and hexaconazole on the mycelial growth on PDA, they showed the specific inhibitory activity against the formation of spores in the vapour phase. With flusilazole and hexaconazole, the effects of the solvent, the applied concentration and the incubating temperature on the activities inhibiting the spore formation were confirmed. Their inhibitory effect on the spore formation in vapour phase was excellent by solving them with dimethylsulfoxide and dimethylformamide among tested solvents, and applying them at high temperature such as 30~35.

In order to better understand the role of antioxidant enzymes in plant stress protection mechanisms, transgenic tobacco (Nicotiana tabacum cv. Xanthi) plants were developed that overexpress both superoxide dismutase (SOD) and ascorbate peroxidase (APX) in chloroplasts. These plants were evaluated for protection against methyl viologen (MV, paraquat)-mediated oxidative damage both in leaf discs and whole plants. Transgenic plants that express either chloroplast-targeted CuZnSOD (C) or MnSOD (M) and APX (A) were developed (referred to as CA plants and AM plants, respectively). These plant lines were crossed to produce plants that express all three transgenes (CMA plants and AMC plants). These plants had higher total APX and SOD activities than non-transgenic (NT) plants and exhibit novel APX and SOD isoenzymes not detected in NT plants. As expected, transgenic plants that expressed single SODs showed levels of protection from MV that were only slightly improved compared to NT plants. The expression of either SOD isoform along with APX led to increased protection while expression of both SODs and APX provided the highest levels of protection against membrane damage in leaf discs and visual symptoms in whole plants.

【A strain of Acremonium strictum, the mycoparasite of Botrytis cinerea, showed strong antifungal activities both in vitro and in vivo against several phytopathogenic fungi. An antifungal substance was purified from the liquid cultures of A. strictum and identified as verlamelin by instrumental analyses. Verlamelin exhibited in vitro antifungal activity against some phytopathogenic fungi such as Magnaporthe grisea, Bipolaris maydis, and Botrytis cinerea, while it was net active against all the bacteria tested. In viva, verlamelin exhibited strong protective and curative activities, particularly against barley powdery mildew. At 100 μg/ml, it inhibited the development of barley powdery mildew with control values of more than 90% in 7-day protective and 2-day curative applications. This is the first report on the production of verlamelin by Acremonium species.】

Fungicidal characteristics of KC10017, an oxadiazole compound, were investigated in a greenhouse. KC10017 showed strong protective activity against rice blast. When KC10017 (0.5 μg/ml solution) was sprayed on leaves, rice blast was controlled almost completely. Its protective activity decreased temporally, reaching 54% of the control value at 14 days after treatment. Further, its curative and systemic effects were not significant even at 100 μg/ml, and KC10017 was not active against the causal fungus, Magnaporthe grisea. However, it inhibited the melanization of appressoria and mycelia in M. grisea. KC10017 is the first oxadiazole compound showing an inhibitory effect on the biosynthesis of melanin in M. grisea. It was further confirmed that the protective activity of KC10017 was counteracted by wound inoculation of M. grisea. These results suggest that a compound with characteristics like KC10017 has potential as a new fungicide for rice blast.

The insecticidal activity of materials derived from the rhizome of turmeric, Curcuma longa, against four agricultural and four stored-product insects was examined using direct contact application method. The biologically active constituent of the Curcuma rhizome was characterized as the sesquiterpene ketone ar-turmerone by spectroscopic analysis. Potencies varied according to insect species and dose. In a test with Nilaparvata lugens female adults, ar-turmerone caused 100 and 64% mortality at 1,000 and 500 ppm, respectively. Against Plutella xylostella larvae, the compound gave 100 and 82% mortality at 1,000 and 500 ppm, respectively. Against Myzus persicae female adults and Spodoptera litura larvae, ar-turmerone at 2,000 ppm was effective but weak insecticidal activity was observed at 1,000 ppm. At a dose of 2.1 mg/cm2, ar-turmerone was almost ineffective (

A Monochoria vaginalis population that survived after treatment with sulfonylurea herbicide-based mixtures was identified in 1997 in the paddy fields in Chonnam province, Korea. The field had been in monoculture rice production and had been treated with sulfonylurea herbicide-based mixtures for 8 consecutive years. In greenhouse studies, the resistant/wild I50 ratios of M. vaginalis to pyrazosulfuron-ethyl were 21.2, 28.5, 23.4, and 12.8 when treated at 2, 7, 14, and 21 days after seeding, respectively. The same trends of I50 ratios of 42.4, 17.2, 9.2, and 6.1 were obtained after treatment with bensulfuron-methyl, respectively. The resistant type of M. vaginalis showed high levels of cross-resistance to pyrazosulfuron-ethyl, bensulfuron-methyl, cyclosulfamuron, and flumetsulam, but not to imazaquin. The resistant type of M. vaginalis did not show multiple resistance to other herbicides having different modes of action, such as simazine, propanil, oxadiazon, butachlor, and 2,4-D. In vitro acetolactate synthase (ALS) assay showed that the pI50 values of bensulfuron-methyl to the wild and resistant type of M. vaginalis were 9.3 and 7.1. Also, the pI50 values of flumetsulam to the wild and resistant type of M. vaginalis were 7.7 and 6.0 but those of imazaquin were 8.3 and 8.2. Acetolactate accumulation in the resistant type of M. vaginalis plants treated with bensulfuron-methyl or flumetsulam followed by 1,1-cyclopropane dicarboxylic acid were significantly higher than that of wild type. However, the accumulation of acetolactate in the plants treated with imazaquin was not significantly different in the wild and the resistant type of M. vaginalis. In vitro and in vivo ALS assay results showed that the resistance mechanism of M. vaginalis might be due to the altered acetolactate synthase.

Fungicidal activity of Piper longum L . fruit-derived materials toward six phytopathogenic fungi, Pyricularia oryzae , Rhizoctonia solani , Botrytis cineria , Phytophthora infestans , Puccinia recondita , and Erysiphe graminis , was tested using a whole plant method in vivo. It was compared with synthetic fungicides (chlorothalonil, dichlofluanid and mancozeb) and four commercially available compounds (eugenol, piperine, piperlongumine, and piperettine) derived from P. longum . The response varied with the plant pathogen tested. At 1 mg ml −1 , the hexane extract of P. longum showed fungicidal activities against P. oryzae , B. cineria , P. infestans , and P. recondita with the control values of 33, 15, 40, and 100%, respectively. A piperidine alkaloid, pipernonaline, was isolated from the hexane fraction using chromatographical techniques and showed a potent fungicidal activity against P. recondita with 91 and 80% control values at the concentration of 0.5 and 0.25 mg ml −1 , respectively. Structural elucidation of pipernonaline was by means of MS, 1 H-NMR and 13 C-NMR. In the test with commercially available components derived from P. longum , piperettine exhibited weak activity against E. graminis , but no activity was observed from treatments with eugenol, piperine, and piperlongumine. In comparison, potent fungicidal activity showed with chlorothalonil against P. infestans at 50 μg ml −1 , dichlofluanid against B. cinerea at 50 μg ml −1 and mancozeb against P. recondite at 5 μg ml −1 . These results may be an indication of at least one of the fungicidal actions of pipernonaline derived from P. longum L . fruit.

In order to develop a new method for measuring foliar uptake of fungicides, Congo Red was selected as a tracer, and optimum procedures were established for washing, extracting and analyzing it and fungicides from leaf surfaces. Congo Red, a water-soluble dye, was not absorbed into cucumber or rice leaf, even in the presence of various surfactants, and was completely washable from leaf surfaces by aqueous acetonitrile solutions. Congo Red and fungicides in washings were quantified to calculate the amount of foliar uptake of the latter, by comparing the ratio to Congo Red. The optimum concentration of Congo Red in a formulation should be established in order to minimize its influence on fungicide uptake. Although Congo Red has proved to be useful with a conventional droplet application method, it will give more realistic and practical results with the spraying method used in the present study.

Phomalactone, 5,6-dihydro-5-hydroxy-6-prop-2-enyl-2H-pyran-2-one, produced by the fungus Nigrospora sphaerica, was tested in vitro against nine plant pathogenic fungi, and specifically inhibited the mycelial growth of Phytophthora infestans, with an MIC value of 2.5 mg litre-1. Its inhibitory activities against sporangium and zoospore germination of P infestans were similar to those against Phytophthora capsici. In vivo, at 100 and 500 mg litre-1, it reduced the development of tomato late blight caused by P infestans.

Summary To analyze the physiological role of each peroxidase (POD) isoenzyme in environmental stress adaptation, transgenic tobacco (Nicotiana tabacum) plants expressing either a sweet potato (Ipomoea batatas) anionic POD (swpa 1) or neutral POD (swpn 1) were tested for responses to oxidant methyl viologen (MV). Fully expanded leaves of both swpa 1- and swpn 1-transgenic plants had about two times higher POD activity than non transformed (NT) plants. When tobacco leaf discs were subjected to MV at 10 and 100 µmol/L, swpa 1-transgenic plants showed about a 25 % reduction in membrane damage relative to swpn 1-transgenic or NT plants. Leaves of swpn 1-transgenic and NT plants were bleached more than those of swpa 1-transgenics by 1 µmol/L MV treatment, whereas all plants were severely damaged at 3 µmol/L MV. These results indicate that the increased H2O2-scavenging capacity provided by the swpa 1 POD (a guaiacol-type POD) contributes to increased protection against MV-mediated oxidative damage. Furthermore, differences in response to oxidant treatments indicate unique functions for the two isoenzymes encoded by swpa 1 and swpn 1.

In order to develop new dry phantom materials that can simulate the effect of electromagnetic wave on human tissues, the dielectric properties of the phantom materials composed of dielectrics, carbon black, and epoxy resin were investigated. For dielectrics/epoxy composite, the dielectric constants increased with the content of dielectric powder and were independent of frequency at the measured frequency range. The dielectric constants and conductivity of carbon black/epoxy composite also in- creased with the carbon black, but it showed the frequency dependence that the complex dielectric constants decreased with increasing frequency. The dielectric con- stants and conductivity corresponding to human tissues could be obtained by combining the frequency dependence of carbon black/epoxy composite with the dielectric proper- ties of dielectrics/epoxy composite and by adjusting the composition ratios of carbon black, dielectrics, and epoxy. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1294 -1302, 2000

Chlorophyll a fluorescence analysis was carried out to investigate the potential relationship between photosynthetic electron transport and herbicidal action mechanism of sulcotrione, norflurazon, diuron, and two experimental herbicides in cucumber cotyledons. The diuron treatment decreased quantum yield of electron transport and photochemical fluorescence quenching ( q P ) immediately but increased the steady-state fluorescence yield ( F t ) greatly in the light, with a decreased magnitude upon dark adaptation. The profile of changes of q P and F t in sulcotrione-treated tissues was similar to that of diuron-treated tissues; however, a decline in quantum yield was faster in diuron-treated tissues. Norflurazon-treated tissues also decreased quantum yield as in sulcotrione-treated tissues, but had a slight increase in F t and a prominent increase in q N in contrast to those of diuron and sulcotrione. Experimental herbicides EK 3651, sulcotrione derivative, and KC 6361, phytoene desaturase inhibitor, also exhibited a similar profile of chlorophyll a fluorescence to that of sulcotrione and norflurazon, respectively. This demonstrates that chlorophyll a fluorescence induction profiles of the chemicals are related to their respective herbicidal activities and can be utilized as a simple way of differentiating the target sites of herbicides in vivo. Based on a correlation between quantum yield inhibition and injury, sulcotrione appears to be closer to diuron than norflurazon. In the combined treatment of herbicides, sulcotrione and diuron had synergistic effect to each other. Our results suggest that sulcotrione inhibits photosynthetic electron transport, in mature cotyledons, through a decrease in plastoquinone pool, which is essential for phytoene desaturase and involved in photosynthetic electron transport as a mediator.

Wheat is known to be relatively tolerant to diphenyl ether herbicides. Growth and physiological responses of wheat to diphenyl ether herbicide oxyfluorfen were examined in comparison with those of oxyfluorfensusceptible barley. Compared to barley, wheat was significantly less susceptible to the herbicide with preemergence and postemergence treatments. The differential susceptibilities of wheat and barley to the herbicide were more apparent with postemergence than with preemergence treatment. The effects of the herbicide on causing cellular leakage, chlorophyll loss, and lipid peroxidation were much lower in wheat than in barley leaves. Protoporphyrin IX accumulated in both wheat and barley leaves treated with oxyfluorfen, in a concentration-dependent manner. However, the magnitude of the protoporphyrin IX accumulation was much lower in wheat than in barley leaves treated with oxyfluorfen at a concentration of higher than 0.33 μM. Protoporphyrinogen oxidase from wheat leaves was found to be less susceptible to oxyfluorfen than that from barley leaves. The I50 concentrations of oxyfluorfen on protoporphyrinogen oxidase activity were approximately 0.2 and 0.06 μM for wheat and barley etioplasts, respectively. Whereas the inhibition of protoporphyrinogen oxidase in barley etioplasts increased with increasing concentration of oxyfluorfen, protoporphyrinogen oxidase in wheat etioplasts was not further inhibited beyond 0.33 μM oxyfluorfen concentrations. In addition, both plant species similarly responded to superoxide anion-generating paraquat and to singlet oxygen-generating rose bengal, implying that the relative tolerance of wheat to oxyfluorfen is not due to protective mechanism against active oxygen species. Our results suggest that the differential susceptibilities of wheat and barley to oxyfluorfen are at least partly due to the differential inhibition of protoporphyrinogen oxidase by the herbicide, and thereby wheat is relatively tolerant to the herbicide.

The effects of SrTiO3 content on the electromagnetic properties and electromagnetic wave-absorbing characteristics of SrTiO3–epoxy composites were investigated. Also, the frequency dispersion behavior of the complex permittivity of composites was demonstrated. The complex permittivity and permeability were measured using a network analyzer in the frequency range of 130 MHz to 10 GHz. As the SrTiO3 content increased, it was found that the complex permittivity and permeability of the composites increased and the resonance frequency moved toward low frequency range. The logarithmic model coincided with the effective permittivity of composite as a function of SrTiO3 content comparatively well. The resonance frequency of composites was found to show good agreement with the theoretical values calculated by the equation proposed in this article. The electromagnetic wave-absorbing behavior showed that the center frequency of attenuation curve was shifted to a lower frequency band with increasing the amount of SrTiO3 and the thickness of composite. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 75–83, 1999

Fluorine was introduced into the 2-position of the side chain of abscisic acid (ABA) analogues by Wittig reaction of α-ionone derivatives with ethyl triethylphosphono-2-fluoroacetate. The effects of the fluorinated analogues were evaluated on inhibition of cress seed germination and inhibition of gibberellin-inducible α-amylase induction in embryoless barley half-seeds. (2E,4E)-2-Fluoro-5-(1‘-hydroxy-2‘,6‘,6‘-trimethyl-2‘-cyclohexen-1‘-yl)-3-methyl-2,4-pentadienoic acid (5b) showed potent inhibitory activity at the same level as ABA in the cress seed germination test, and 5b also inhibited gibberellin-inducible α-amylase induction at 4 × 10-6, 3 times the concentration of ABA (1 × 10-6) for 50% inhibition of α-amylase production. 5b also showed dehydrin induction activity. These results indicate that fluorinated ABA analogues mimic ABA action and can be a lead for a plant growth regulator which regulates plant growth or protects plants from environmental stresses. Keywords: Inhibition of cress seed germin...

A new experimental fungicide KC10017 (3-[4′-bromo-2′, 6′-dimethylphenoxy]methyl-4-[(3″-methylphenyl) aminocarbonyl]methyl-1,2,4-oxadiazol-5-one) completely controlled rice blast disease at more than 1.0 μg/ml without curative activity. When the chemical was applied after the inoculation was made with injury, the fungicide had no effect on controlling rice blast. The fungicide at concentrations of more than 1 μg/ml blocked appressorial melanization and penetration of cellophane membrane byMagnaporthe griseaP-2 without affecting fungal growth, spore germination, and appressorial formation. To elucidate the target site of KC10017 in melanin biosynthesis inhibition,M. griseaP-2 was grown in potato dextrose broths treated with both KC10017 and tricyclazole. The mycelia and culture media of cultures treated with both KC10017 and tricyclazole at a concentration of 5 μg/ml each became colorless like as the cultures treated with KC10017 alone, whereas the tricyclazole-treated cultures exhibited red color. Shunt products of 3,4-dihydro-3,4,8-trihydroxy-1-(2H)-naphthalenone, 3,4-dihydro-4,8-dihydroxy-1-(2H)-naphthalenone, 3,4-dihydro-4,6,8-trihydroxy-1-(2H)-naphthalenone, and 4-hydroxyscytalone were absent or present in only trace amounts in the cultures treated with KC10017 alone or both KC10017 and tricyclazole. However, they were detected at much higher levels in the cultures treated with tricyclazole alone. On the other hand, appressorial melanization and penetration ability inM. griseatreated with KC10017 was recovered by the addition of scytalone. These results demonstrate that the target site of KC10017 in melanin biosynthesis inhibition is at the pentaketide synthesis step and/or at the pentaketide cyclization step prior to 1,3,6,8-tetrahydroxynaphthalene formation.

An isolate of the indigenous fungus Plectosporium tabacinum was isolated from arrowhead (Sagittaria trifolia) in Yusung, Korea in 1990 and evaluated in laboratory and growth chamber tests as a potential mycoherbicide. The fungus grew comparatively slowly on potato dextrose agar and corn meal agar, attaining a diameter of 65 mm after 12 days at 25°C. Conidia were mass-produced in shake-cultures or in a fermentor using potato dextrose broth containing yeast extract (0.5%, wt/vol) at 25°C. When arrowhead seedlings at the 2- to 3-leaf stage were inoculated with conidial suspensions (2 × 107 conidia/ml) and incubated in a dew chamber for 18 h at 25°C, the plants developed small, brown spots on the leaves and petioles in 2 days, and were blighted completely within 7 days after inoculation. This effect was consistent on arrowhead plants from the 2- to 5-leaf stage. Another arrowhead species, S. pygmaea, was as susceptible as S. trifolia to the pathogen. Several crops, including rice, barley, and wheat and 34 other common weed species, were immune. In small-scale field tests in paddy fields during the summers of 1992 and 1993, a mean reduction of 71.3% in the number of arrowhead plants was observed following a foliar spray of a conidial suspension (107 conidia/ml). These results indicate that P. tabacinum has potential as a selective mycoherbicide for arrowhead control.

The effects of frequency, volume fraction of carbon black, and porosity on the complex permittivity of the epoxy-carbon black composites were investigated and the frequency dispersion behavior model for the complex permittivity was proposed. In the epoxy-carbon black composites, the frequency dispersion behaviors of the complex permittivity changed from relaxation spectrum to resonance spectrum with increasing the amount of carbon black. The complex permittivity of the composites increased with decreasing the porosity. Comparing the complex permittivity of the composites filled with 2 vol % of carbon black with the values obtained from three types of previously reported model equations, the relaxation behavior coincided with the Havriliak-Negami model. The damping and asymmetrical factor values were increased with increasing porosity in the composites. The empirical equation proposed here was useful in describing the complex permittivity of the composites of >3 vol % carbon black with resonance type. The damping factor (γ) decreased as the filler content increased, but the asymmetrical factor (κ) increased reversely.

In a search for plant extracts with potent in vivo antifungal activity against various plant pathogenic fungi, the methanol extract of the Curcuma longa rhizomes effectively controlled the development of rice blast catised by Magnaporthe grisea and tomato late blight caused by Phytophthora infestans. Three curcuminoids such as curcumin, demethoxycurcumin, and bisdemethoxycurcumin were purified from the methanol extract of C. longa rhizomes as antifungal principles. Among the three curcuminoids, demethoxycurcumin was the most active to both rice blast and tomato late blight, followed in order by curcumin and bisdemethoxycurcumin. However, they all exhibited no or little in vivo antifungal activity against other fungal pathogens causing rice sheath blight (Corticium sasaki), tomato gray mold (Botrytis cinerea), wheat leaf rust (Puccinia recondita), or barley powdery mildew (Blumeria graminis f. sp. hordel).

In order to examine whether defensive enzymes are related to the resistance of Botrytis cinerea to dicarboximide fungicides, catalase (CAT) and superoxide dismutase (SOD) activities were compared in a dicarboximide-susceptible (DS) isolate and a dicarboximide-resistant (DR) isolate of B. cinerea . In the absence of vinclozolin, the DR isolate had 1.5- and 3.0-fold higher CAT and SOD activities, respectively, than the DS isolate. When the DR isolate was incubated with 2 μM vinclozolin, CAT and SOD activities were considerably enhanced at 1 h after the fungicide treatment and then decreased to the level of their respective control. In the DS isolate, however, such changes of the enzyme activities were not significant. Native polyacrylamide gel electrophoresis and activity staining of CAT and SOD revealed that both enzymes had two isoforms and that the staining intensities of the isoforms were different in the DS and the DR isolates. Both isoforms of CAT appeared to have higher staining intensity in the DR isolate than in the DS isolate, whereas one isoform of SOD was more preferentially distinct in the DR isolate. The enhanced isoform of SOD in the DR isolate was found to be Cu,Zn-SOD. When the DR isolate was incubated with 2 μM vinclozolin, both isoforms of CAT from the DR isolate tended to become slightly more apparent at 1 h after the fungicide treatment, but their staining activity was slightly reduced after the prolonged treatment of the fungicide. No such changes of the staining intensity were observed in the CAT isoforms from the DS isolate and in the SOD isoforms either from the DS or from the DR isolate. Our results demonstrate that the DR isolate has enhanced activities of CAT and SOD regardless of the presence of vinclozolin. They also show that a much higher amount of the Cu,Zn-SOD isoform exists in the DR isolate than in the DS isolate. Therefore, it can be concluded that enhanced activities of CAT and SOD, mostly of Cu,Zn-SOD, at least partly confer the resistance of B. cinerea to the dicarboximide fungicides.