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Two plant growth-promoting rhizobacteria, Pseudomonas corrugata CCR80 and Chryseobacterium indologenes ISE14, previously reported as suppressive to Phytophthora blight of pepper caused by Phytophthora capsici in the field were selected for use of this study. The effects of the strains on microbial activities, populations, and communities in pepper rhizosphere with or without pathogen inoculation were examined at 40, 80, and 120 days after transplanting (DAT) in the field in 2008 and 2009. To investigate the microbial effects, we used culture-dependent and -independent techniques such as plate counts on selective media, and fluorescein diacetate and denaturing gradient gel electrophoresis (DGGE) analyses. Root treatment with the strains increased total microbial activities in rhizosphere soil compared with controls (untreated, metalaxyl, or Escherichia coli DH5α) over the sampling time regardless of pathogen inoculation; however, microbial activities were greatly decreased in all treatments at 40–80 DAT. The strains also impacted the populations of bacterial and fungal functional groups. Eight fungal species, frequently observed on the medium for total fungi, were identified; these populations were significantly affected by the treatments: three species by metalaxyl, one by strain DH5α, one by strain ISE14, and none by strain CCR80 in both years. The DGGE analysis revealed that the strains affected bacterial and fungal community structure; the test strains increased the bacterial community composition, especially at 80 DAT, but had little effect on fungal community at later DAT. Taken together, strains CCR80 and ISE14 increased microbial activities and community composition, and affected certain microbial populations in the rhizosphere of pepper plants in the field, which might play significant roles in the suppression of Phytophthora blight of pepper.

Aims: Previously, we selected a bacterial strain (GSE09) antagonistic to Phytophthora capsici on pepper, which produced a volatile compound (2,4-di-tert-butylphenol), inhibiting the pathogen. In this study, we identified strain GSE09 and characterized some of the biological traits of this strain in relation to its antagonistic properties against P. capsici. In addition, we examined bacterial colonization on the root surface or in rhizosphere soil and the effect of various concentrations of the volatile compound and strain GSE09 on pathogen development and radicle infection as well as radicle growth. Methods and Results: Strain GSE09 was identified as Flavobacterium johnsoniae, which forms biofilms and produces indolic compounds and biosurfactant but not hydrogen cyanide (HCN) with little or low levels of antifungal activity and swimming and swarming activities. Fl. johnsoniae GSE09 effectively colonized on pepper root, rhizosphere, and bulk (pot) soil, which reduced the pathogen colonization in the roots and disease severity in the plants. Various concentrations of 2,4-di-tert-butylphenol or strain GSE09 inhibited pathogen development (mycelial growth, sporulation, and zoospore germination) in I-plate (a plastic plate containing a center partition). In addition, germinated seeds treated with the compound (1–100 μg ml−1) or the strain (102–1010 cells ml−1) significantly reduced radicle infection by P. capsici without radicle growth inhibition. Conclusions: These results indicate that colonization of pepper root and rhizosphere by the Fl. johnsoniae strain GSE09, which can form biofilms and produce indolic compounds, biosurfactant, and 2,4-di-tert-butylphenol, might provide effective biocontrol activity against P. capsici. Significance and Impact of the Study: To our knowledge, this is the first study demonstrating that the Fl. johnsoniae strain GSE09, as a potential biocontrol agent, can effectively protect pepper plants against P. capsici infection by colonizing the roots.

In this study, we determined the effect of controlling rice weevils on the mycoflora of stored brown rice by using Anisopteromalus calandrae (Howard), a parasite of the rice weevil. The mycoflora in brown rice with the parasitoid was similar to that without the parasitoid; however, the dominant mold species differed. Without the parasitoid, Aspergillus candidus Link and Penicillium islandicum Sopp were the dominant species, whereas Aspergillus penicilloides Speg. and P. islandicum were dominant when the parasitoid was present. The difference appeared to be due mainly to the difference in the grain moisture content with and without the parasitoid. A. candidus was the dominant species in the communities without the parasitoid and was not observed when the weevils were suppressed. P. islandicum dominated or co-dominated regardless of the presence of the parasitoid which suggested that P. islandicum is tolerant to low grain moisture content or is positively affected by the presence of the rice weevil.

A representative isolate KU53 of the predominant Penicillium species was obtained from rice samples from rice processing complexes of National Agricultural Cooperative Federation in Korea. In this study, isolate KU53 was identified by its morphological and molecular characteristics. The macro- and microscopic characteristics of isolate KU53 were compared with the P. fellutanum reference isolate KCTC16913 on different media; isolate KU53 was generally identical to those of the reference isolate KCTC16913. In a molecular-based identification, the β-tubulin and translation elongation factor 1-alpha sequences of isolate KU53 was most closely related to those of P. fellutanum. Thus, isolate KU53 from stored rice could be identified as P. fellutanum, some isolates of which are known to produce mycotoxin-related metabolites. To our knowledge, this is the first detection of P. fellutanum from stored rice in Korea.

Laboratory of Plant Disease and Biocontrol, Korea University, Seoul 136-713, Korea(Received on March 23, 2011; Accepted on April 17, 2011)During the summer of 2005, specimens of soybean culti-vars (Daepung, Daewon, Hwanggeum and Taegwang)showing frogeye leaf spot (FLS) were obtained fromvarious areas in Korea. Eight isolates identified asCercospora sojina were inoculated on the adaxial leafsurfaces of 63 Korean soybean cultivars; the diseaseresponses to each isolate were evaluated 14 days and 21days after inoculation. Based on the disease responses(resistant or susceptible) of the cultivars by the isolates,a set of cultivars (Anpeong, Bogwang, Cheongdu No. 1,Cheongja No. 3, Dachae, Daemang, Jangwon, Namhae,Sowon, Taegwang) were selected and inoculated withseven isolates for further testing pathogenic variance.Interestingly, 6 out of 7 tested C. sojina isolates revealeddifferential ability in infecting different soybean culti-vars. This result may indicate the possibility of new raceoccurrence or pathogenic variation; this also presentsevidence for prevalent FLS occurrence during humidand hot weather in Korea.Keywords : Cercospora sojina, frogeye leaf spot, soybeancultivarCercospora sojina is the causal agent of frogeye leaf spot(FLS) on soybeans [Glycine max (L.) Merr.]. The pathogencan infect leaves, stems, and seeds of the host plant. Thesymptoms on leaves are circular or angular, and 1−5 mm indiameter. The water soaked and mature symptomatic spotsappear suddenly and develop into brown spots surroundedby a dark reddish brown margin (Hartman et al., 1999).Upon aging of a lesion, the center becomes grey to lightbrown in color and forms conidiophores and conidia.Lesions appear at time intervals and join together to formirregular lesions. When lesions cover about 30% of the totalleaf area, the leaf quickly withers and falls prematurely(Hartman et al., 1999; Phillips and Boerma, 1981), resultingin more than 35% yield loss through a reduction of seedsize during hot, humid weather (Laviolette et al., 1970;Mian et al., 1998; Mwase and Kapooria, 2000; Wrather etal., 2001; Yorinori, 1981). Epidemics and declines of FLS incidence have shownrepeated cycles. New C. sojina races, infecting cultivarsthat are widely grown and resistant to established races,appear; thus, the disease is prevalent. Since a cultivar, that isresistant to a new prevalent race and a previous establishedrace, had been developed, widely grown, the diseaseincidence has been declined (Athow and Probst, 1952;Athow et al., 1962; Phillips and Boerma, 1981; Ross,1968). Many races have been reported worldwide: 12 racesin the USA, 11 races in the People’s Republic of China,more than 20 races in South America and a race in Japan(Hartman et al., 1999). Thus, monitoring C. sojina racesand developing resistant soybean cultivars should beconcerned in widely soybean-producing countries. In Korea, although soybeans have been widely cultivatedand many soybean cultivars are inbred, there has been littleresearch concerning disease response of cultivars against C.sojina. Therefore, the objective of this study was to deter-mine disease responses of ten soybean cultivars to seven C.sojina isolates for race identification in Korea. FLS-diseased leaves of soybean collected from northernGyeonggi, Gangwon, Gyeongsang, and Chungcheong pro-vinces in July to September, 2005 were provided fromGyonggi-do Agricultural Research and Extension Services,Northern Agriculture Research Station, Yeoncheon, Korea.For fungal isolation, single spore was isolated from spotson leaves and cultured on potato dextrose agar (PDA).After incubation of these plates at 25

Sang, M. K., and Kim, K. D. 2011. Biocontrol activity and primed systemic resistance by compost water extracts against anthracnoses of pepper and cucumber. Phytopathology 101:732-740. We investigated direct and indirect effects of compost water extracts (CWEs) from Iljuk-3, Iljuk-7, Shinong-8, and Shinong-9 for the control of anthracnoses caused by Colletotrichum coccodes on pepper and C. orbiculare on cucumber. All tested CWEs significantly (P < 0.05) inhibited in vitro conidial germination and appressorium formation of the fungal pathogens; however, DL-β-amino-n-butyric acid (BABA) failed to inhibit the conidial development of the pathogens. Direct treatments of the CWEs and BABA on pepper and cucumber leaves at 1 and 3 days before or after inoculation significantly (P < 0.05) reduced anthracnose severities; Iljuk-3, Shinong-9, and BABA for pepper and Iljuk-7 for cucumber had more protective activities than curative activities. In addition, root treatment of CWEs suppressed anthracnoses on the plants by the pathogens; however, CWE treatment on lower leaves failed to reduce the diseases on the upper leaves of the plants. The CWE root treatments enhanced not only the expression of the pathogenesis-related (PR) genes CABPR1, CABGLU, CAChi2, CaPR-4, CAPO1, and CaPR-10 in pepper and PR1-1a, PR-2, PR-3, and APOX in cucumber but also the activity of β-1,3-glucanase, chitinase, and peroxidase and the generation of hydrogen peroxide in pepper and cucumber under pathogen-inoculated conditions. However, the CWE treatments failed to induce the plant responses under pathogen-free conditions. These results indicated that the CWEs had direct effects, reducing anthracnoses by C. coccodes on pepper leaves and C. orbiculare on cucumber leaves through protective and curative effects. In addition, CWE root treatments could induce systemic resistance in the primed state against pathogens on plant leaves that enhanced PR gene expression, defense-related enzyme production, and hydrogen peroxide generation rapidly and effectively immediately after pathogen infection. Thus, the CWEs might suppress anthracnoses on leaves of both pepper and cucumber through primed (priming-mediated) systemic resistance.

We previously selected rhizobacterial strains CCR04, CCR80, GSE09, ISE13, and ISE14, which were antagonistic to Phytophthora blight of pepper. In this study, we investigated the effects of root treatment of rhizobacteria on anthracnose occurrence, ripening, and yield of pepper fruit in the plastic house and field in 2008 and 2009. We also examined the effects of volatiles produced by the strains on fruit ripening and on mycelial growth and spore development of Colletotrichum acutatum and Phytophthora capsici in the laboratory, identifying the volatile compounds by gas chromatography–mass spectrometry (GC-MS). In the house tests, all strains significantly (P < 0.05) reduced anthracnose incidence on pepper fruit; strains GSE09 and ISE14 consistently produced higher numbers of pepper fruit or increased the fresh weight of red fruit more than the controls in both years. In the field tests, all strains significantly (P < 0.05) reduced anthracnose occurrence on either green or red pepper fruit; strain ISE14 consistently produced higher numbers or increased fresh weights of red fruit more than the controls in both years. In the laboratory tests, volatiles produced by strains GSE09 and ISE13 only stimulated maturation of pepper fruit from green (unripe) to red (ripe) fruit; the volatiles of certain strains inhibited the growth and development of C. acutatum and P. capsici. On the other hand, GC-MS analysis of volatiles of strains GSE09 and ISE13 revealed 17 distinct compounds in both strains, including decane, dodecane, 1,3-di-tert-butylbenzene, tetradecane, 2,4-di-tert-butylphenol, and hexadecane. Among these compounds, 2,4-di-tert-butylphenol only stimulated fruit ripening and inhibited growth and development of the pathogens. Taken together, strains GSE09 and ISE14 effectively reduced anthracnose occurrence and stimulated pepper fruit ripening and yield, possibly via bacterial volatiles. Therefore, these two strains could be potential agents for controlling Phytophthora blight and anthracnose, and for increasing fruit ripening and yield. To our knowledge, this is the first report of volatiles such as 2,4-di-tert-butylphenol produced by rhizobacteria being related to both fruit ripening and pathogen inhibition.

The efficacy of resistance in tomato plants, induced by rhizobacteria isolated from Jeju Island in Korea, against late blight disease caused by Phytophthora infestans was tested. Among the bacterial isolates tested, pre-inoculation with four isolates induced an effective defense against late blight. The four isolates, TRH423-3, TRH427-2, KRJ502-1 and KRY505-3, were identified as Burkholderia gladioli, Miamiensis avidus, Acinetobacter quenomosp and Bacillus cereus, respectively, by sequencing the ribosomal intergenic spacer region. They also promoted the growth of tomato seedlings. To illustrate resistance mechanisms, the infection process by P. infestans was examined using a fluorescence microscope. There were no noticeable differences in the rate of germination and appressorium formation between the untreated and pre-inoculated plants. However, callose was more frequently formed at the penetration sites on the leaves of pre-inoculated plants than the untreated plants, suggesting that these rhizobacterial isolates induce defense responses against P. infestans.

Occurrence of plant diseases is dependent on various factors in the agricultural system. Due to recent extensive environmental climate changes, i.e. global warming, agricultural systems such as planting dates and cultivars are being affected. Gradual transition in disease occurrence and incidence in the agricultural fields can also be affected by direct and/or indirect environmental changes. In this study, we evaluated disease occurrence and incidence in soybean plants to investigate whether it could be related with cultivars, planting dates and geographical differences in Korea in 2008. Soybean cultivars including `Taekwang`, `Pungsan`, `Cheongja 3`, `Saeol`, and `Dawon` were planted in four different dates, May 15, June 1, June 15, and June 30, in two locations, Suwon, and Naju. Soybean diseases such as wild fire and bacterial pustule were mainly found depending on cultivars, planting dates, and areas. Wild fire occurred severely on cv. `Taekwang` while bacterial blight did on cv. `Dawon` among tested cultivars. Disease developments of wild fire and bacterial blight generally decreased in delayed planting regardless of cultivars.

We investigated the effects of water extracts of composts (CWE) from commercial compost facilities for controlling root and foliar infection of pepper plants by Phytophthora capsici. Among 47 CWE tested, CWE from composts Iljuk-3, Iljuk-7, Shinong-8, and Shinong-9 significantly (P < 0.05) inhibited zoospore germination, germ tube elongation, mycelial growth, and population of P. capsici. All selected CWE significantly (P < 0.05) reduced the disease incidence and severity in the seedling and plant assays compared with the controls. However, there were no significant differences in zoospore germination, disease incidence, and disease severity between treatments of untreated, autoclaved, and filtered CWE. In addition, CWE significantly (P < 0.05) suppressed leaf infection of P. capsici through induced systemic resistance (ISR) in plants root-drenched with CWE. The tested CWE enhanced the expression of the pathogenesis-related genes, CABPR1, CABGLU, CAChi2, CaPR-4, CAPO1, or CaPR-10 as well as β-1,3-glucanase, chitinase, and peroxidase activities, which resulted in enhanced plant defense against P. capsici in pepper plants. Moreover, the CWE enhanced the chemical and structural defenses of the plants, including H2O2 generation in the leaves and lignin accumulation in the stems. The CWE could also suppress other fungal pathogens (Colletotrichum coccodes in pepper leaves and C. orbiculare in cucumber leaves) through ISR; however, it failed to inhibit other bacterial pathogens (Xanthomonas campestris pv. vesicatoria in pepper leaves and Pseudomonas syringae pv. lachrymans in cucumber leaves). These results suggest that a heat-stable chemical(s) in the CWE can suppress root and foliar infection by P. capsici in pepper plants. In addition, these suppressions might result from direct inhibition of development and population of P. capsici for root infection, as well as indirect inhibition of foliar infection through ISR with broad-spectrum protection.

We evaluated microbial populations and aflatoxin production in unhulled and white rice from rice processing complexes of the National Agricultural Cooperative Federation in five regions in Korea and identified three predominant Aspergillus species. Fungal and bacterial populations in rice samples were significantly different between regions in 2007. Aflatoxins were also detected and varied at the levels of 2.45 - 3.43 ng per g unhulled rice grain and 1.29 - 2.09 ng per g white rice grain. Unhulled rice generally detected higher level of aflatoxins than white rice regardless of sampling regions; however, no significant differences were found in Anseong and Cheonan in 2005 and Cheonan and Gimpo in 2007. Aflatoxin production between sampling regions was not different regardless of rice type and sampling year. Although the fungal diversity was highly distinct from region to region, three Aspergillus isolates were predominant in the rice samples; thus, representative isolates AC317, AF57, and AF8 were selected and identified based on their morphological and molecular characteristics. Consequently, isolates AC317, AF57, and AF8 were identified as A. candidus, A. flavus, and A. fumigatus, respectively. These fungi can produce mycotoxins that are harmful for consumers and thus it is important to detect and reduce the population of storage fungi in rice.

In this study, we evaluated and compared the virulence of Magnaporthe oryzae isolates sensitive and resistant to the phosphorothiolate fungicides, edifenphos and iprobenfos on rice plants treated with or without fungicides. Monoconidial isolates of M. oryzae sensitive and resistant to the fungicides were selected from our previous relative mycelial growth assay of 1080 isolates on fungicide-amended media. When six-leaf stage rice plants treated with different concentrations of the fungicides were inoculated with four resistant and four sensitive isolates of M. oryzae , the lowest concentrations showing virulence differences were twice the minimum inhibitory concentrations (MICs) of edifenphos (40 μg a.i. ml −1 ) and iprobenfos (110 μg a.i. ml −1 ). Therefore, two MICs were used as discriminatory concentrations for further virulence tests of 20 sensitive and 20 resistant isolates of M. oryzae . Isolates resistant to edifenphos produced greater disease severity and susceptible lesion number per leaf area (SLNLA) than sensitive isolates on rice plants regardless of treatments. Reduction of disease severity and SLNLA was greater for sensitive than resistant isolates on edifenphos-treated plants compared to untreated controls. Similar results were obtained with iprobenfos, but disease severity or SLNLA of resistant isolates were not affected by iprobenfos compared to untreated controls. In this study, it was evident that resistant isolates of M. oryzae were more virulent than sensitive isolates on rice plants and were less affected by the phosphorothiolate fungicides. Therefore, rice blast management programs should consider a potential adaptation in M. oryzae populations for increased phosphorothiolate-fungicide resistance.

In this study, we characterized the bacterial strain KJ2C12 in relation with its biocontrol activity against Phytophthora capsici on pepper, and identified this strain using morphological, physiological, biochemical, fatty acid methyl ester, and 16S rRNA gene sequence analyses. Strain KJ2C12 significantly (P

We have previously obtained a representative isolate KU101 of the predominant Penicillium species from rice under indoor storage conditions. In this study we attempted to characterize isolate KU101 using its morphological and molecular characteristics. When the micro- and macroscopic characteristics of isolate KU101 were compared with the P. islandicum reference isolate KCCM 34763, isolate KU101 was generally identical to those of isolate KCCM 34763, however, isolate KU101 grew faster and produced more orange to red pigments than isolate KCCM 34763. In a molecular-based identification, the nuclear sequence of the ITS1-5.8S-ITS2 region of isolate KU101 was most closely related to that of P. islandicum. Therefore, these results indicated that isolate KU101 from stored rice could be identified as P. islandicum, some isolates of which are known to produce mycotoxins.

In this study, the sensitivity of Magnaporthe oryzae isolates from different geographic areas in Korea to two phosphorothiolate (PTL) fungicides, edifenphos and iprobenfos, was determined. A total of 1080 M. oryzae isolates were collected from rice-cultivating fields in 11 locations throughout Korea in 1997 and 1998. The minimum inhibitory concentrations (MICs) of edifenphos (20 μg a.i. ml −1 ) and iprobenfos (55 μg a.i. ml −1 ) against seven representative sensitive isolates of M. oryzae were determined from the dose-response curves, and the MICs were then used as single discriminatory concentrations for the detection of fungicide resistance. Of the 1080 tested isolates, the isolates less sensitive to edifenphos and iprobenfos were 57 and 84%, respectively, and 53% of the isolates were less sensitive to both fungicides. Approximately 11% of all tested isolates showed no growth at the MICs of the tested fungicides. Isolates with a relative mycelial growth of 0.05 to edifenphos occurred at the greatest frequency (33%); isolates with a relative growth of 0.3 to iprobenfos occurred at the greatest frequency (23%). The frequency distribution of isolates sensitive to either edifenphos or iprobenfos varied with geographic location. The two-sample median test yielded high medians in the Kwangju and Chonju isolates for edifenphos, and in the Kwangju, Donghae, and Yangyang isolates for iprobenfos, but low medians in the Kangnung isolates for edifenphos and in the Kangnung, Gwangju, and Chunchon isolates for iprobenfos, respectively, as compared to the isolates from the other locations. Analysis of Spearman's rank correlation test showed a significantly positive relationship ( r = 0.490, P M. oryzae populations collected from different geographic areas in Korea, and isolates less sensitive to these fungicides exhibit cross-resistance with each other.

This study was conducted to select antagonistic rhizobacteria against Phytophthora capsici using a sequential screening procedure and to evaluate control efficacy of drench or root-dip treatments with the selected strains against Phytophthora blight of pepper in the field. Out of 439 bacterial strains, 16 potentially antagonistic strains were screened through radicle and seedling assays and in planta trials, and five candidate strains, CCR04, CCR80, GSE09, ISE13, and ISE14, were selected for field tests. In 2005 and 2006 tests, the control efficacy of the five strains was examined against Phytophthora blight of pepper plants drenched with the bacterial suspension in artificial pathogen inoculation. Three strains, CCR04, CCR80, and ISE14, consistently reduced the disease in both tests. As another form of application, the control efficacy of root-dip treatment was examined on pepper plants just prior to transplanting in the field with natural inoculation in 2006 and 2007. In these tests, four strains, CCR04, CCR80, GSE09, and ISE14, showed consistently good control efficacy against P. capsici, and strains CCR80 and ISE14 increased pepper fruit yield. The strain-treated roots had less infection rates by P. capsici compared with control roots regardless of drench or root-dip treatments. In addition, the strains did not affect the populations of bacteria and fungi in the rhizosphere soil. Therefore, the antagonistic strains selected from the screening procedure provided significant protection against P. capsici through pepper root colonization. These strains could be applied by either drench or root-dip treatment as alternatives to agricultural chemicals to control Phytophthora blight of pepper.

In healthy, untreated pepper plants, transcripts of thionin (CATHION1) gene were induced in an organ-specific manner, as revealed by RNA blot analysis and in situ hybridization. The CATHION1 mRNAs were expressed in stems and flowers as well as roots, but not in leaves and fruits. In the stem and root tissues, the CATHION1 mRNA was present in endodermis and the phloem. In contrast, the transcripts were uniformly located in all the cells of flower tissues. Northern blot analysis and in situ hybridization were also performed to examine the temporal and spatial expression patterns of thionin (CATHION1) mRNA in leaf and fruit tissues of pepper (Capsicum annuum L.) infected by anthracnose pathogens Colletotrichum coccodes and C. gloeosporioides, respectively. Transcripts of the CATHION1 gene were more rapidly induced in pepper leaves at the 4- than at the 8-leaf stage by C. coccodes infection. Typical anthracnose symptoms were observed on green pepper fruits inoculated with C. gloeosporioides, but not on red pepper fruits. The transcript accumulation was more pronounced in green fruits than in red fruits upon C. gloeosporioides infection. The CATHION1 transcripts were detected in the phloem cells infected by anthracnose pathogens.

Carbon utilization by Chryseobacterium strain KJ1R5 was studied to enhance its biocontrol activity against Phytophthora capsid. Chryseobacterium strain KJ1R5 has previously been shown to control Phytophthora blight of pepper (Capsicum annuum L.). Strain KJ1R5 could utilize carbon sources such as L-arabinose, D-cellobiose, and D-galactose well. P. capsici could utilize D-glucose well, showing the absorbencies ranged from 0.577 to 0.767 at 600nm. When 2% L-arabinose, which could only be utilized by the bio-control strain KJ1R5, was amended into the bacterial suspension, the efficacy of biological control increased. Among the amendments of various carbon sources into bacterial suspension, L-arabinose and D-(+)-glucose significantly enhanced biological control activity, resulting in a reduction of disease incidence to 6.9%, compared to 21.9% for the strain KJ1R5 alone and 81.3% for P. capsici inoculation alone, indicating that amendment with specific carbon sources could increase the biological control activity.

This research was conducted to evaluate fungal and bacterial populations in unhulled and brown rice under indoor storage conditions, and to examine the relationship between microbial populations and environmental conditions such as temperature and relative humidity. The temperature and relative humidity of the storage room ranged from and 23.3% to 44.2%, respectively. Total fungal and bacterial populations remained relatively stable over the storage period. Predominant fungi included Aspergillus candidus, A. flavus, A. fumigatus, and Penicillium spp.; the predominant bacteria were Bacillus, Microbacterium, Sphingomonas, and Methylobacterium spp. Total fungi and bacteria were not significantly correlated with either unhulled (r

This research was conducted to develop a sequential screening procedure for bacteria antagonistic against Phytophthora capsici, and to evaluate control efficacy by candidate antagonistic bacteria selected by this procedure against Phytophthora blight of pepper in the field. A total of 231 bacterial strains were isolated from soils and roots of cucumber, pepper, and tomato plants grown in fields at 12 locations in Korea in 2000 and 2001. From these, 88 strains were pre-selected using a radicle assay. These strains were then screened in a seedling assay with 2-week-old pepper seedlings inoculated with 1000 zoospores of P. capsici g−1 potting mixture, a concentration which caused complete death of the seedlings. Based on the results of this screen, 15 potentially antagonistic strains with at least 50% control efficacy of seedling infection by P. capsici were selected and further tested in 5-week-old pepper plants. In the in planta trials, four bacterial strains, KJ1R5, KJ2C12, KJ9C8, and 11S16, consistently showed significant (P=0.05) disease suppression against P. capsici infection and were examined as candidate biocontrol agents for their antagonistic effects in the field by artificial inoculation in 2001 and 2002. Plants treated with the bacterial strains KJ1R5, KJ2C12, and KJ9C8 had significantly (P=0.05) lower disease severity and incidence than untreated controls in at least one test. These field test results have demonstrated that the radicle and seedling assays are very effective as part of the screening procedure to select candidate antagonistic bacteria against P. capsici on pepper. Therefore, effective biocontrol agents for Phytophthora blight of pepper could be selected through the sequential screening procedure developed in this study.

Chromogranins and secretogranins have traditionally been known as marker proteins of secretory granules that contain the highest concentrations of cellular calcium, reaching approximately 40 mM. In addition, chromogranin B was also shown to exist in the nucleus, localizing in the putative inositol 1,4,5-trisphosphate (IP3)-sensitive nucleoplasmic Ca2+ store vesicles. Chromogranins A (CGA) and B (CGB) are high-capacity, low-affinity Ca2+ binding proteins, binding 30-90 mol of Ca2+/mol with dissociation constants (Kd) of 1.5-4 mM. Yet the Ca2+-binding property of secretogranins has not been studied. Here, we show the localization of secretogranin II (SgII) in the nucleus, more specifically, in the IP3-sensitive nucleoplasmic Ca2+ store vesicles along with CGB and the IP3 receptors. We have also determined the Ca2+-binding property of SgII and found that SgII binds 61 mol of Ca2+/mol (910 nmol Ca2+/mg) with a Kd of 3.0 mM at the intragranular pH 5.5 and 30 mol of Ca2+/mol (440 nmol Ca2+/mg) with a Kd of 2.2 mM at a near-physiological pH 7.5. Chromogranin B also bound 50 mol of Ca2+/mol (670 nmol Ca2+/mg) with a Kd of 3.1 mM at pH 7.5. Given the high-capacity, low-affinity Ca2+-binding property of SgII and its presence in the IP3-sensitive nucleoplasmic Ca2+ store vesicles, these results suggest that SgII may function in the storage and control of Ca2+ in the nucleus through its interaction with CGB in the nucleoplasmic vesicles.

The nucleus also contains the inositol 1,4,5-trisphosphate receptor (IP3R)/Ca2+ channels in the nucleoplasm proper independent of the nuclear envelope or the cytoplasm. The nuclear IP3R/Ca2+ channels were shown to be present in small IP3-dependent nucleoplasmic Ca2+ store vesicles, yet no information is available regarding the IP3 sensitivity of nuclear IP3R/Ca2+ channels. Here, we show that nuclear IP3R/Ca2+ channels are 3-4-fold more sensitive to IP3 than cytoplasmic ones in both neuroendocrine PC12 cells and nonneuroendocrine NIH3T3 cells. Given the presence of phosphoinositides and phospholipase C and the importance of IP3-mediated Ca2+ signaling in the nucleus, the high IP3 sensitivity of nuclear IP3R/Ca2+ channels seemed to reflect the physiological needs of the nucleus to finely control the IP3-dependent Ca2+ concentrations. It was further shown that the IP3R/Ca2+ channels of secretory cells are 7-8-fold more sensitive to IP3 than those of nonsecretory cells. This difference appeared to result from the presence of secretory cell marker protein chromogranins (thus secretory granules) in secretory cells; expression of chromogranins in NIH3T3 cells increased the IP3 sensitivity of both nuclear and cytoplasmic IP3R/Ca2+ channels by approximately 4-6-fold. In contrast, suppression of chromogranin A expression in PC12 cells changed the EC50 of IP3 sensitivity for cytoplasmic IP3R/Ca2+ channels from 17 to 47 nM, whereas suppression of chromogranin B expression changed the EC50 of cytoplasmic IP3R/Ca2+ channels from 17 to 102 nM and the nuclear ones from 4.3 to 35 nM. Given that secretion is the major function of secretory cells and is under a tight control of intracellular Ca2+ concentrations, the high IP3 sensitivity appears to reflect the physiological roles of secretory cells.

This study was to examine the efficacy of a root-dipping application of antagonistic bacterial strains for the control of Phytophthora blight of pepper caused by P. capcisi, and to evaluate their plant growth-promoting effects in the field in 2005 and 2006. The candidate antagonistic rhizobacterial strains CCR04, CCR80, GSE09, ISE13, and ISE14 were treated by dipping plant roots with bacterial suspensions prior to transplanting. The candidate rhizobacterial strains CCR04, CCR80, GSE09, and ISE14 significantly (P

Functional Analyses of Three Gα and One Gβ Subunits in Gibberella zeaeComparison between Wild Strains of Pitoporus betulinus Collected from a Single TreeEcological Study of Sparassis crispa in Gwan...

A severe epidemic of basal stem rot of the cactus Hylocereus trigonus occurred in 2001, in greenhouses of Goyang City, South Korea, possibly due to continuous cultivation in soil beds. Fusarium oxysporum was isolated and its pathogenicity was demonstrated. Inoculation of mycelial plugs on stem disks of cactus showed brown discoloration. Inoculation of a spore suspension of F. oxysporum (1.40×104 or 1.24×108 spores ml−1) on the underground basal stems of cactus plants, followed by incubation at 28 °C in a growth chamber, led to the development of brown spots identical to the original symptoms after 3 months. The effect of amendment with spent mushroom sawdust, calcium cyanamide, straw and solarization on the development of the disease was studied. In a greenhouse study, amendment with spent mushroom sawdust compost to the disease-conducive soil reduced the disease incidence to 3–12%, as compared to 44–59% with the unamended disease-conducive soil. Autoclaved spent mushroom sawdust compost did not reduce the disease incidence. The bacterial (1.95×1011 cfu g−1) and fungal population (9.50×107 cfu g−1) of spent mushroom sawdust was significantly higher than those (2.0×109 cfu g−1 and 0.13×105 g−1 for bacteria and fungi, respectively) of disease-conducive soil. Also, disease-suppressive soil had a higher fungal population (1.25×105 cfu g−1) compared to disease-conducive soil (0.13×105 cfu g−1). This trend was repeated in the second experiment. Solarization with and without calcium cyanamide of disease-conducive soil reduced effectively pathogen population and disease development, resulting in 16–53% disease incidence, as compared to 81% in the untreated control. Rice straw as an organic amendment did not have synergistic effect on disease control when it was used along with calcium cyanamide for solarization. The results indicate that the control of basal stem rot with spent mushroom sawdust compost may be due to biological activity, and that solarization with calcium cyanamide is a highly effective tool for controlling basal stem rot.

Notes on Three Species of the Genus Euphoriomyces (Laboulbeniales) from KoreaTaxonomic Studies on Myelochroa from KoreaMolecular Analysis of Korean Anzia opuntiella (Lichenized Ascomycota) Based on...

Stored cereal crops form the major component of the world's food supply. It is well known that post-harvest crop losses, due to insects and microbes, cause significant economic waste in both developed and developing countries. In general, the environment in storage facilities is prone to rapid pest development, leading to significant grain losses. Rice weevil (Sitophilus oryzae L.) is one pest of cereal crops that deposits its eggs on or in a seed. To detect rice weevil in stored rice, we developed PCR-based molecular markers of Sitophilus oryzae. Several sets of PCR primers from the ‘internal transcribed spacer 2’ gene of S. oryzae were analyzed to identify molecular markers that are specific to the S. oryzae genome. Among six sets of molecular markers identified, three were found to be useful for identifying rice weevil. Our results demonstrate that a PCR marker system permits rapid and reliable identification of weevil in stored grain. Furthermore, this PCR assay would expand the choice of too...

The potential role of two pathogen-induced pepper genes, encoding basic pathogenesis-related protein 1 (CABPR1) and ascorbate peroxidase-like 1 (CAPOA1), in tolerance against phytopathogens was examined in transgenic tomato (Lycopersicum esculentum cv. House Momotaro) plants. Polymerase chain reaction and reverse transcription-polymerase chain reaction analyses using gene-specific primers revealed that the pepper CABPR1 and CAPOA1 genes were integrated into the tomato genome. The constitutive expression of CABPR1 and CAPOA1 in the tomato did not exhibit any morphological abnormalities. However, these transgenic tomato plants showed enhanced tolerance to the oomycete pathogen Phytophthora capsici, and very weak resistance to the bacterial pathogen Pseudomonas syringae pv. tomato. These results suggest that overexpression of CABPR1 and CAPOA1 in tomato plants altered their resistance responses to pathogenic attack.

In this biocontrol research, we evaluated disease suppressive effects of antagonistic bacterial strains ISE13 and KJ1R5 against Korean ginseng root rot caused by P. eaetorum. We also examined the effects of nutrient solution in the hydroponic culture system for Korean ginseng on biological activity of the bacterial strains. As results of dual culture tests of the bacterial strains on juice agar, the strain ISE13 showed antifungal activity against P. eaetorum and other plant pathogenic fungi, but the strain KJ1R5 did not. When their inhibitory effects against infection of P. eaetorum on the roots grown in either nutrient solution or water were tested, the strains ISE13 and KJ1R5 inhibited the disease severity of Korean ginseng roots only grown with water, compared to buffer-treated, inoculated controls. However, the nutrient solution used for hydroponic cultures of ginseng in pots caused higher levels of disease severity by the strains ISE13 and KJ1R5 from to and from to , respectively. In this study, the bacterial strains ISE13 and KJ1R5 could be potentially biocontrol agents to suppress Korean ginseng root rot caused by P. eaetorum. However, more attention using nutrient solution in hydroponic cultures for Korean ginseng production should be applied in biocontrol of plant diseases using the antagonistic microorganisms.

A method was developed using scanned computer images and software programs to measure the lesion area on leaves with cucumber anthracnose caused by Colletotrichum orbiculare. After cucumber plants were inoculated with various concentrations of conidia, lesions on diseased leaves were scanned, manipulated with Adobe Photoshop 6.0, and measured using the blob analysis feature in Matrox Inspector 2.2. The method requires relatively low-cost equipment including a scanner, a personal computer, and two programs: Adobe Photoshop 6.0 and Matrox Inspector 2.2. Because stored images are used, the lesion area can be measured as time permits. Processing the images requires about 3 min per sample. The image assessment accurately detected anthracnose lesions on cucumber leaves and could be applied to other foliar necrotic or spot diseases.

In order to determine the role of ascorbate peroxidase, an antioxidant enzyme, in the cellular responses to oxidative stress and pathogens, transgenic tobacco plants were generated, using the Capsicum annuum ascorbate peroxidase-like 1 gene (CAPOA1), under the control of the CaMV 35S promoter. High levels of CAPOA1 gene expression were observed in the transgenic plants, with a 2-fold increase in total peroxidase activity. The constitutive expression of CAPOA1 in the tobacco exhibited no morphological abnormalities, while significantly increased growth was observed in transgenic plants, as compared to control plants. The CAPOA1-overexpressed plants exhibited increased tolerance to methyl viologen-mediated oxidative stress, and also enhanced resistance to the oomycete pathogen, Phytophthora nicotianae. However, the transgenic plants were not found to be resistant to the bacterial pathogen, Pseudomonas syringae pv. tabaci, but were weakly resistant to Ralstonia solanacearum. Our results suggested that the overproduction of ascorbate peroxidase increased peroxidase activity that enhances active oxygen scavenging system, leading to oxidative stress tolerance and oomycete pathogen resistance. # 2005 Elsevier Ireland Ltd. All rights reserved.

Citrus melanose is one of the most important diseases in orchards cultivating citrus in the world. Although the disease does not cause yield loss, the profitability of the infected fruits is often reduced in the fresh-market, resulting in economic loss. In this study, disease reduction was proven by pre-treatment with Pseudomonas putida strain THJ609-3. In order to illustrate mechanism of the disease reduction by the bacterial strain, the infection behaviors of Diaporthe citri and necrosis deposit of plant tissue were observed using a fluorescence microscope. On the leaves pre-treated with the strain THJ609-3, germination rates of D. citri conidia were significantly decreased compared to those of the untreated control. Scanning electron microscopical observations showed that bacterial cells were attached to the surface of fungal hyphae. Furthermore, morphological change of germ tubes of the conidia was detected. These results suggest that the disease reduction may be caused by the direct antifungal activity of the bacterial strain on the leaf surfaces.

Colletotrichum gloeosporioides isolate KG13 caused necrotic, sunken anthracnose symptoms on unwounded, wax-removed, and wounded green pepper fruits and on wounded red fruits 7 days after inoculation. Hypersensitive reactions with small brownish discolorations, on some occasions, were found on unwounded red fruits. The isolate produced whitish symptoms with brown margins, but not the typical anthracnose on red fruits wax-removed by chloroform treatment. Generally, wax-removed red fruits, but not green ones, produced larger lesions and more conidia than untreated controls. Wounded pepper fruits had larger lesions than those with other treatments. More germinated conidia, appressoria, and infection hyphae were found on wax-removed fruits than on controls; however, differences between green and red fruits were not found. Cuticular wax layers of fruits were dissolved partially by chloroform and the outer epidermal cells were disrupted slightly. Anthracnose development was negatively related with fruit developmental stage. Well-developed fruits had more cuticular wax than less developed fruits. These results suggest that the cuticular wax layers of pepper fruits may play a significant role in fruit infection by C. gloeosporioides isolate KG13, and mainly determine the incompatibility of red fruits to the isolate. Biochemical differences may also play a role. Zusammenfassung Bedeutung der kutikularen Wachsschichten gruner und roter Paprikaschoten fur die Infektion mit Colletotrichum gloesporiodes Das Isolat KG13 von Colletotrichum gloeosporioides rief bei unverletzten grunen Paprikaschoten, deren Wachsschicht entfernt worden war, bei verletzten grunen Paprikaschoten und bei verletzten roten Paprikaschoten 7 Tage nach der Inokulation nektrotische, eingesunken Brennflecken hervor. Bei einigen unverletzten roten Schoten traten Hypersensitivitatsreaktionen auf, die sich als kleine braunliche Verfarbungen zeigten. Bei roten Fruchten, deren Wachsschicht durch eine Chloroformbehandlung entfernt worden war, rief das Isolat weisliche Lasionen mit braunem Rand, aber keine typischen Brennflecken hervor. Bei den roten Fruchten, deren Wachsschicht entfernt worden war, waren die Lasionen allgemein groser und die Konidien zahlreicher als bei den unbehandelten Kontrollen; bei den grunen Fruchten war dies nicht der Fall. Bei verletzten Paprikafruchten warendie Lasionen groser als bei den anders behandelten Schoten. Auf den Fruchten, deren Wachsschicht entfernt worden war, fanden sich im Vergleich zu den Kontrollen mehr gekeimte Konidien, mehr Appressorien und mehr Infektionshyphen; Unterschiede zwischen grunen und roten Paprikaschoten waren dabei nicht feststellbar. Die kutikularen Wachsschichten der Fruchte wurden durch Chloroform teilweise entfernt, wahrend die auseren Epidermiszellen mechanisch leicht verletzt wurden. Die Entwicklung der Brennfleckenkrankheit war mit dem Entwicklungsstadium der Paprikaschoten negativ korreliert. Gut entwickelte Fruchte besaszen mehr kutikulares Wachs als weniger entwickelte. Diese Ergebnisse legen nahe, das die kutikularen Wachsschichten von Paprikaschoten grose Bedeutung fur die Infektion der Schoten durch das Isolat KG13 von C. gloeosporioides haben und masgeblich fur die Inkompatibilitat roter Schoten fur das Isolat verantwortlich sein konnten. Auch biochemische Unterschiede spielen hier moglicherweise eine Rolle.

Stored rice was collected from rice processing complexes of National Agricultural Cooperative Federation of 11 regions in Korea to evaluate the occurrence of fungi and bacteria and to identify the predominant fungi and bacteria to the genus levels. Most rice samples generally produced the higher levels of fungi and bacteria than white rice. The occurrence of fungi and bacteria varied in various locations of Korea. Among fungi observed, Aspergillus spp. and Penicillium spp. were dominant in the samples and Aspergillus spp. were observed more frequently than Penicillium spp. Predominant bacteria from rice and white rice samples tentatively belonged to the Genus Bacillus, Pectobacterium, Pantoea, and Microbacterium according to BIOLOG and FAME analyses. The results of this study showed that rice in Korea was contaminated in a relatively high level by two dominant storage fungi such as Aspergillus spp. and Penicillium spp. In addition, occurrence of mycotoxins in rice by the fungi could be possible and thus it is necessary to control the storage fungi.

Induced systemic resistance (ISR) can be activated by biotic agents, including root-associated beneficial bacteria to inhibit pathogen infection. We investigated priming-mediated ISR in cucumber induced by Pseudomonas azotoformans GC-B19 and Paenibacillus elgii MM-B22 against Colletotrichum orbiculare (causal fungus of anthracnose). In addition, we examined whether this ISR expression was bacterial density-dependent by assessing peroxidase activity in the presence and absence of the pathogen. As a result, root treatment with the ISR-eliciting strains GC-B19 and MM-B22 or the chemical inducer DL-β-amino-n-butyric acid (positive control) significantly inhibited fungal infection process (conidial germination and appressorium formation) and disease severity compared with the non-ISR-eliciting strain, Pseudomonas aeruginosa PK-B09 (negative control), and MgSO4 solution (untreated control). These treatments effectively induced rapid elicitation of hypersensitive reaction-like cell death with H2O2 generations, and accumulation of defense-related enzymes (β-1,3-glucanase, chitinase, and peroxidase) in cucumber leaves in the “primed” state against C. orbiculare. In addition, ISR expression was dependent on the bacterial cell density in the rhizosphere. This ISR expression was derived from the presence of sustained bacterial populations ranging from 104 to 106 cells/g of potting mix over a period of time after introduction of bacteria (106 to 1010 cells/g of potting mix) into the rhizosphere. Taken together, these results suggest that priming-mediated ISR against C. orbiculare in cucumber can be induced in a bacterial density-dependent manner by Pseudomonas azotoformans GC-B19 and Paenibacillus elgii MM-B22.

Importing citrus fruits infected by Asiatic citrus canker caused by Xanthomonas citri pv. citri (Xcc) can act as an inoculum source for the disease epidemic in citrus canker-free countries. In this study, the pathogenicity of the causal agent of Asiatic citrus canker surviving on infected Satsuma mandarin fruits was evaluated. The washing solution of infected Satsuma mandarin fruits did not cause lesion formation on the citrus leaves. However, a typical citrus canker lesion was formed on the leaves after inoculation with higher concentrations of the inoculum from the washing solution (washing solution II). It indicated that the pathogenicity of the citrus canker surviving on the symptomatic Satsuma mandarin fruits was not changed. Scanning electron microscopic observation showed that the numbers of bacterial cells on the leaves of Satsuma mandarin which inoculated with the washing solution directly (washing solution I) was less compared to those of leaves inoculated with the washing solution II. This result spports that the pathogenicity of Xcc surviving on Satsuma mandarin fruits may not be changed but that the sucessful infection of citrus caker may depend on the concentration of the inoculum.

Sectors of rice blast fungus, Pyricularia grisea, frequently appeared on potato dextrose agar amended with edifenphos and iprobenfos. Thus, we assessed the sector-forming frequency of isolates of P. grisea and compared the fungicide sensitivity between wild types and sectors against the fungicides. The 905 isolates of the fungus were obtained from rice-growing locations in Korea from 1997-1998. When the isolates were grown on potato dextrose agar amended with minimal inhibitory concentrations of edifenphos (20 g a.i./ml)and iprobenfos (55 g a.i./ml), they produced sectors that overcame the effect of the fungicides. Among the 905 isolates tested, 9.0% produced sectors against edifenphos and 5.6%, against iprobenfos. Different sector-forming frequencies were also observed among the 11 locations of Korea. Sectors obtained from the fungicide-amended media generally grew more than their counterpart wild types grown on the media with either edifenphos or iprobenfos, regardless of their origins. In this study, greater relative growth of sectors over wild types of tested isolates can support the resistant characteristic of the fungus to survive against the fungicides. Therefore, the results indicate that the sectoring in rice blast fungus, P. grisea, may play a role in the occurrence of fungicide resistance.

The yellow-pigmented, Gram-stain-negative, rod-shaped bacterium KJ1R5T was isolated from the root of a pepper plant grown in a field in Kwangju, Korea. Strain KJ1R5T was characterized by physiological, biochemical, and molecular genetic analyses. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain KJ1R5T was most closely related to members of the genus Chryseobacterium , and that the strain exhibited the highest similarities with type strains of Chryseobacterium vrystaatense (97.0 %) and Chryseobacterium rhizosphaerae (97.1 %). DNA–DNA hybridization reassociation values between strain KJ1R5T and type strains of C. vrystaatense KACC 11675T and C. rhizosphaerae KACC 14918T were 46.9 and 38.4 %, respectively. The DNA G+C content of KJ1R5T is 40.2 mol%. The predominant respiratory quinone of KJ1R5T was menaquinone MK-6; major cellular fatty acids were iso-C15 : 0, summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), iso-C17 : 1ω9c, and iso-C17 : 0 3-OH. On the basis of these phenotypic and genotypic characteristics, the strain significantly differed from representative strains belonging to the genus Chryseobacterium . Thus, we propose that strain KJ1R5T represents a novel species of the genus Chryseobacterium , named Chryseobacterium kwangjuense sp. nov. The type strain is KJ1R5T ( = KACC 13029T = JCM 15904T).

Background The gliotransmitters released from astrocytes are deemed to play key roles in the glial cell-neuron communication for normal function of the brain. The gliotransmitters, such as glutamate, ATP, D-serine, neuropeptide Y, are stored in vesicles of astrocytes and secreted following the inositol 1,4,5-trisphosphate (IP3)-induced intracellular Ca2+ releases. Yet studies on the identity of the IP3-dependent intracellular Ca2+ stores remain virtually unexplored. Principal Findings We have therefore studied the potential existence of the IP3-sensitive intracellular Ca2+ stores in the cytoplasm of astrocytes using human brain tissue samples in contrast to cultured astrocytes that had primarily been used in the past. It was thus found that secretory granule marker proteins chromogranins and secretogranin II localize in the large dense core vesicles of astrocytes, thereby confirming the large dense core vesicles as bona fide secretory granules. Moreover, consistent with the major IP3-dependent intracellular Ca2+ store role of secretory granules in secretory cells, secretory granules of astrocytes also contained all three (types 1, 2, and 3) IP3R isoforms. Significance Given that the secretory granule marker proteins chromogranins and secretogranin II are high-capacity, low-affinity Ca2+ storage proteins and chromogranins interact with the IP3Rs to activate the IP3R/Ca2+ channels, i.e., increase both the mean open time and the open probability of the channels, these results imply that secretory granules of astrocytes function as the IP3-sensitive intracellular Ca2+ store.

Antifungal bacteria for biological control of plant diseases or production of novel antibiotics to plant pathogens were isolated in 1997 from various soils of Ansung, Chunan, Koyang, and Paju in Ko...

BACKGROUND: Microbial secondary metabolites are a rich source of antifungal agents and have merit as alternatives to synthetic fungicides. To develop disease control agents against powdery mildew, the lipopeptide antibiotic neopeptins were identified from the culture broth of a Streptomyces sp., and in vivo control efficacy of the compounds was evaluated on cucumber plants under glasshouse conditions. RESULTS: The Streptomyces sp. KNF2047 antagonistic against powdery mildew development in cucumber plants was isolated from a soil sample. Antifungal compounds were purified from the culture broth and identified as neopeptin A and B. In vitro microtitre assays revealed the inhibitory activities of the compounds in the range 128–512 µg mL−1 against the mycelial growth of Alternaria mali, Botrytis cinerea, Cladosporium cucumerinum, Colletotrichum lagenarium, Didimella bryoniae and Magnaporthe grisea. Although neither compound showed remarkable in vitro antifungal activity against other plant pathogenic fungi, a mixture of neopeptins (484 mg of neopeptin A and 290 mg of neopeptin B per gram of partially purified powder) showed potent protective and curative activity against cucumber powdery mildew in vivo. The disease control activity of the neopeptins at a concentration of 2.4 mg L−1 was 92.1%, which was similar to that of the commercial fungicide fenarimol (89.3% at 63 mg L−1) and that of the commercial biocontrol agent Actinovate (67.4% at 2 × 107 cfu L−1). CONCLUSION: Neopeptin mixtures isolated from Streptomyces sp. KNF2047 showed potent disease control activity against powdery mildew development on cucumber plants. Copyright © 2007 Society of Chemical Industry

Colletotrichum gloeosporioides is a common pathogenic fungus in many plants. To investigate the specificity of the isolate C. gloeosporioides to green fruits, fungal behaviours and anthracnose development on green and red pepper fruits were compared using light and stereo microscopic techniques. When the isolate of C. gloeosporioides was inoculated on both green and red fruits, conidial germination, appressoria, and infection hyphae were observed on both fruits within 24 h after inoculation. The fungal invasion and colonization continued to the epidermal cells of green fruits, but not to those of red ones. Initial anthracnose symptoms were detected only on green fruits at 2 days after inoculation resulting in typical sunken necrosis within 5 days after inoculation. Thus the specificity of the isolate to green fruits may be due to successful invasion and colonization of the infection hyphae from appressoria into the epidermal cells through epicuticular layers of green pepper fnats, but not on red ones. Zusammenfassung Colletotrichum gloeosporioides hat ein breites Wirtpflanzenspektrum. Um die Spezifizitat eines C. gloeosporioides-Isolates bei der Infektion von grunen Fruchten zu untersuchen, wurden das Verhalten vom Pilz tmd die Anthraknoseentwick-lung bei grilnen tind roten Fruchten rait Hilfe von licht- und stereomikroskopischen Methoden verglichen. Nach der Inokulation von grttoen bzw roten Frtlchten mit dem C gloeosporioides-lsolaX wurden die Konidienkeimung, die Appressorienbildung und die Bildung von Infektionshyphen innerhalb von 24 h beobachtet. Die Infektion und Besiedlung der Fruchte bis zu den epidermalen Zeilen konnte bei grunen jedoch nicht bei roten Fruchten nachgewiesen werden. Die anfanglichen Symptome einer Anthraknose wurden nur bei grunen Fruchten 2 Tage nach der Inokulation beobachtet, welche zu den typischen, vertieften Nekrosen innerbalb 5 Tagen nach der Inokulation fuhrten. Von daher konnte die Spezifizitat des Isolats zu grilnen Fruchten sich darauf beziehen, das nach der Appressorienbildung die Infektionshyphen die epidermalen Zeilen durch die epikutikularen Schichten bei grunen Frflchten erfolgreich eindringen und kolonisieren konnen, jedoch nicht bei roten Fruchten.

A pepper gene, CABPR1, which encodes basic pathogenesis-related protein 1, has been reported to be strongly induced after ethephon treatment, wounding, and tobacco mosaic virus infection. The potential role of CABPR1 in tolerance of biotic or abiotic stresses was examined in transgenic Nicotiana tabacum cv. xanthi plants. Overexpression of CABPR1 in tobacco plants enhanced tolerance not only to heavy metal stresses, but also to the oomycete pathogen Phytophthora nicotianae, and the bacterial pathogens Ralstonia solanacearum and Pseudomonas syringae pv. tabaci. RT-PCR revealed that the CABPR1 transgene increased expression of the PR-Q and glutathione S-transferase genes, but decreased expression of the PR-1a and thaumatin genes. Moreover, these transgenic lines exhibited significant decreases in total peroxidase activity and transcription level, suggesting that overexpression of CABPR1 in tobacco cells altered the balance of redox systems. Redox imbalance in transgenic lines may lead to H(2)O(2) accumulation, triggering tolerance to biotic and abiotic stresses.