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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.

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...

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.

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.

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.

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.

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.