Biocontrol activity and induction of systemic resistance in pepper by compost water extracts against Phytophthora capsici.

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 beta-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 H(2)O(2) 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.

Sang MK ，Kim JG ，Kim KD 《PHYTOPATHOLOGY》

Biocontrol activity and primed systemic resistance by compost water extracts against anthracnoses of pepper and cucumber.

Sang MK ，Kim KD 《PHYTOPATHOLOGY》

Identification of the pepper SAR8.2 gene as a molecular marker for pathogen infection, abiotic elicitors and environmental stresses in Capsicum annuum.

Pepper ( Capsicum annuum L.) SAR8.2 genes, designated CASAR82A, B and C, which are induced by all the biotic and abiotic stresses, were isolated from a pepper cDNA library constructed with the mRNAs from pepper plants infected with Xanthomonas campestris pv. vesicatoria. The pepper CASAR82A, B and C gene products, which are very similar to each other in amino acid sequences, have 43-50% homology with those of tobacco SAR8.2 genes. The CASAR8.2 genes were not constitutively expressed in any of the organs of healthy pepper plants. In contrast, the CASAR82A gene was locally or systemically induced in pepper plants infected by X. campestris pv. vesicatoria, Colletotrichum coccodes or Phytophthora capsici. Strong induction of the CASAR82A gene also was found in pepper leaves treated with ethylene, methyl jasmonate, indole-3-acetic acid, abscisic acid, salicylic acid, benzothiadiazole, DL-beta- n-amino butyric acid or hydrogen peroxide. Interestingly, the transcription of the CASAR82A gene was rapidly triggered by high salinity, drought or low-temperature stresses, but not by mechanical wounding. In situ hybridization results revealed that the CASAR82A mRNAs were localized in phloem and epidermal cells of pepper leaf and stem tissues infected by C. coccodes and P. capsici, or treated with salicylic acid. These results thus suggest that pepper SAR8.2 genes may be valuable as a molecular marker for the detection of various pathogen infections, abiotic elicitors and environmental stresses.

Lee SC ，Hwang BK 《PLANTA》

Antifungal activity of salaceyin A against Colletotrichum orbiculare and Phytophthora capsici.

Park CN ，Lee D ，Kim W ，Hong Y ，Ahn JS ，Kim BS ... -  《JOURNAL OF BASIC MICROBIOLOGY》

Screening of bacterial antagonists for biological control of Phytophthora blight of pepper.

The aim of this study was to assess the potential of bacterial antagonists to control Phytophthora blight of pepper caused by P. capsici using different screening methods. Among a collection of fluorescent pseudomonas isolated from the rhizosphere of pepper, twelve isolates were initially selected based on dual culture assay on potato dextrose agar and corn meal agar. Further, these twelve isolates were screened for the reduction of disease severity caused by P. capsici using detached leaves and seedling assay. Most of the antagonists showed varying levels of antagonism against P. capsici in both detached leaves and seedlings assay. In addition, few isolates increased shoot and root length of pepper in seedling assays. Among them, isolate PS119 showing highest ability to reduce the disease severity in the in vitro seedling assay was found to be the most efficient antagonists against P. capsici in the in vivo biological control tests. These results indicate that the in vitro seedling assay can be used as a rapid and more accurate technique for the selection of promising biocontrol agents against P. capsici.

Rajkumar M ，Lee WH ，Lee KJ 《JOURNAL OF BASIC MICROBIOLOGY》