scholarly journals A Target-Site-Specific Screening System for Antifungal Compounds on Appressorium Formation in Magnaporthe grisea

2000 ◽  
Vol 90 (10) ◽  
pp. 1162-1168 ◽  
Author(s):  
Hong-Sik Oh ◽  
Yong-Hwan Lee
Keyword(s):  
Ethyl Acetate ◽  
Rice Blast ◽  
Magnaporthe Grisea ◽  
Pathogenic Fungi ◽  
Antifungal Compounds ◽  
Screening System ◽  
Appressorium Formation ◽  
Culture Filtrates ◽  
Water Fractions ◽  
Chemical Fungicides

Chemical fungicides are a major method of control for plant diseases in spite of potential negative effects on the environment and the appearance of resistant strains. Development of new chemical fungicides has been largely dependent upon in vivo efficacy tests in the greenhouse or in fields, which is in contrast to target-oriented in vitro screening systems widely used in the pharmaceutical field. To establish a target-site—specific screening system for antifungal compounds, specific inhibition on appressorium formation of the rice blast fungus Magnaporthe grisea was employed. For many plant-pathogenic fungi, including M. grisea, appressorium formation is an essential step to infect host plants. Among 1,000 culture filtrates of members of the class Actinomycetes and fungi, five (A5005, A5008, A5314, A5387, and A5397) from the class Actinomycetes showed differential inhibitory effects on appressorium formation of M. grisea in a dosage-dependent manner. Three (A5005, A5314, and A5387) of these were further fractionated into ethyl acetate and water fractions. The ethyl acetate fraction of A5005 and both the ethyl acetate and water fractions from A5314 and A5387 inhibited appressorium formation, while conidial germination remained little affected. Inhibition of appressorium formation by the ethyl acetate or water fraction was reversed by the exogenous addition of cyclic AMP. Significantly reduced numbers of conidia with appressoria were observed on rice leaves in the presence of culture filtrates. Furthermore, these culture filtrates also exhibited significant disease control of rice blast in the greenhouse. This rapid and target-oriented screening system could be adopted to screen candidate compounds for rice blast control and could be applicable for other appressorium-forming, plant-pathogenic fungi.

Proteome analysis of rice blast fungus (Magnaporthe grisea) proteome during appressorium formation

PROTEOMICS ◽  
2004 ◽  
Vol 4 (11) ◽  
pp. 3579-3587 ◽  
Author(s):  
Sun Tae Kim ◽  
Seok Yu ◽  
Sang Gon Kim ◽  
Han Ju Kim ◽  
Sun Young Kang ◽  
...  
Keyword(s):  
Rice Blast ◽  
Magnaporthe Grisea ◽  
Proteome Analysis ◽  
Rice Blast Fungus ◽  
Appressorium Formation ◽  
Blast Fungus

scholarly journals Regulation of the MPG1 Hydrophobin Gene in the Rice Blast Fungus Magnaporthe grisea

2002 ◽  
Vol 15 (12) ◽  
pp. 1253-1267 ◽  
Author(s):  
Darren M. Soanes ◽  
Michael J. Kershaw ◽  
R. Neil Cooley ◽  
Nicholas J. Talbot
Keyword(s):  
Rice Blast ◽  
Magnaporthe Grisea ◽  
Fluorescent Protein ◽  
De Novo ◽  
Rice Blast Fungus ◽  
Appressorium Formation ◽  
Plant Infection ◽  
Blast Fungus ◽  
Encoding Gene ◽  
High Level

The hydrophobin-encoding gene MPG1 of the rice blast fungus Magnaporthe grisea is highly expressed during the initial stages of host plant infection and targeted deletion of the gene results in a mutant strain that is reduced in virulence, conidiation, and appressorium formation. The green fluorescent protein-encoding allele sGFP was used as a reporter to investigate regulatory genes that control MPG1 expression. The MAP kinase-encoding gene PMK1 and the wide domain regulators of nitrogen source utilization, NPR1 and NUT1, were required for full expression of MPG1 in response to starvation stress. The CPKA gene, encoding the catalytic subunit of protein kinase A, was required for repression of MPG1 during growth in rich nutrient conditions. During appressorium morphogenesis, high-level MPG1 expression was found to require the CPKA and NPR1 genes. Expression of a destabilized GFP allele indicated that de novo MPG1 expression occurs during appressorium formation. Three regions of the MPG1 promoter were identified which are required for high-level expression of MPG1 during appressorium formation and are necessary for the biological activity of the MPG1 hydrophobin during spore formation and plant infection.

scholarly journals Fungal jasmonate as a novel morphogenetic signal for pathogenesis

2021 ◽  
Author(s):  
Yingyao Liu ◽  
Martin Pagac ◽  
Fan Yang ◽  
Rajesh Narhari Patkar ◽  
Naweed I Naqvi
Keyword(s):  
Cyclic Amp ◽  
Jasmonic Acid ◽  
Vegetative Growth ◽  
Rice Blast ◽  
Pathogenic Fungi ◽  
Appressorium Formation ◽  
Epistasis Analysis ◽  
Delayed Initiation ◽  
Developmental Switch ◽  
Cyclic Amp Signaling

A key question that has remained unanswered is how pathogenic fungi switch from vegetative growth to infection-related morphogenesis during a disease cycle. Here, we identify a fungal oxylipin analogous to the well-known phytohormone jasmonic acid, as the principal morphogenesis signal responsible for such a developmental switch to pathogenicity in the rice-blast fungus Magnaporthe oryzae. We explored the molecular function(s) of such intrinsic jasmonic acid during pathogenic differentiation in M. oryzae via OPR1, which encodes a 12-Oxo-phytodienoic Acid Reductase essential for its biosynthesis. Loss of OPR1 led to prolonged vegetative growth, and a delayed initiation and improper development of infection structures in M. oryzae, reminiscent of phenotypes observed in mutants (e.g. pth11Δ and cpkAΔ) that are compromised for cyclic AMP signaling. Genetic- or chemical-complementation completely restored proper germ tube growth and appressorium formation in opr1Δ. Liquid chromatography mass spectrometry-based quantification revealed increased OPDA accumulation and a significant decrease in JA levels in the opr1Δ. Most interestingly, exogenous jasmonic acid also restored appressorium formation in the pth11Δ mutant that lacks G protein/cyclic AMP signaling. Epistasis analysis placed fungal jasmonate upstream of the cyclic AMP signaling in rice blast. Lastly, we show that intrinsic jasmonate orchestrates the cessation of vegetative phase and initiates pathogenic development via a regulatory interaction with the cyclic AMP cascade and redox signaling in rice blast.

Effects of Antifungal Compounds on Conidial Germination and on the Induction of Appressorium Formation of Magnaporthe grisea

1999 ◽  
Vol 54 (11) ◽  
pp. 903-908 ◽  
Author(s):  
Frank Eilbert ◽  
Eckhard Thines ◽  
Heidrun Anke
Keyword(s):  
Magnaporthe Grisea ◽  
Sodium Cyanide ◽  
Coupling Agents ◽  
Antifungal Compounds ◽  
Appressorium Formation ◽  
Respiratory Inhibitors ◽  
High Concentrations ◽  
Different Strains ◽  
Cyanide Resistant Respiration ◽  
Higher Sensitivity

Abstract Appressorium formation in germinating conidia of Magnaporthe grisea was induced on a hydrophilic (noninductive) surface by antifungal compounds. Respiratory inhibitors or un­ coupling agents such as strobilurins, antimycin A , myxothiazol, rotenone, pterulone A , and oligomycin A were particularly effective whereas sodium cyanide had no effect. Cyclosporin A was effective only at high concentrations. These differentiation-inducing effects were only observed at subfungicidal concentrations at which more than 50% of the germinating conidia formed appressoria. Cycloheximide, nystatin, amphotericin B, and papulacandin A did not induce appressoria. Different strains of M. grisea displayed the same overall response to the inhibitors, varying merely in the percentage of appressoria formed. A combination of the respiratory inhibitors with 2-phenyl-4H -1-benzopyran-4-one (flavone), diphenyleneiodonium (DPI), or salicylhydroxamic acid (SHAM), compounds which interfere with the cyanide-resistant respiration, resulted in a higher sensitivity of the strains towards the respiratory inhibitors, but had no effect on appressorium formation.

scholarly journals Plant Disease Control Efficacy of Platycladus orientalis and Its Antifungal Compounds

Plants ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1496
Author(s):  
Sohyun Bae ◽  
Jae Woo Han ◽  
Quang Le Dang ◽  
Hun Kim ◽  
Gyung Ja Choi
Keyword(s):  
Disease Control ◽  
Rice Blast ◽  
Plant Disease ◽  
Methanol Extract ◽  
Crop Protection ◽  
Ethyl Acetate Fraction ◽  
Antifungal Compounds ◽  
Control Efficacy ◽  
Platycladus Orientalis ◽  
Plant Disease Control

Plants contain a number of bioactive compounds that exhibit antimicrobial activity, which can be recognized as an important source of agrochemicals for plant disease control. In searching for natural alternatives to synthetic fungicides, we found that a methanol extract of the plant species Platycladus orientalis suppressed the disease development of rice blast caused by Magnaporthe oryzae. Through a series of chromatography procedures in combination with activity-guided fractionation, we isolated and identified a total of eleven compounds including four labdane-type diterpenes (1–4), six isopimarane-type diterpenes (5–10), and one sesquiterpene (11). Of the identified compounds, the MIC values of compounds 1, 2, 5 & 6 mixture, 9, and 11 ranged from 100 to 200 μg/mL against M. oryzae, whereas the other compounds were over 200 μg/mL. When rice plants were treated with the antifungal compounds, compounds 1, 2, and 9 effectively suppressed the development of rice blast at all concentrations tested by over 75% compared to the non-treatment control. In addition, a mixture of compounds 5 & 6 that constituted 66% of the P. orientalis ethyl acetate fraction also exhibited a moderate disease control efficacy. Together, our data suggest that the methanol extract of P. orientalis including terpenoid compounds has potential as a crop protection agent.

scholarly journals Inhibition of Fungal Appressorium Formation by Pepper (Capsicum annuum) Esterase

2001 ◽  
Vol 14 (1) ◽  
pp. 80-85 ◽  
Author(s):  
Young Soon Kim ◽  
Hyun Hwa Lee ◽  
Moon Kyung Ko ◽  
Chae Eun Song ◽  
Cheol-Yong Bae ◽  
...  
Keyword(s):  
Recombinant Protein ◽  
Capsicum Annuum ◽  
Magnaporthe Grisea ◽  
Dependent Manner ◽  
Appressorium Formation ◽  
Glutathione S Transferase ◽  
Porcine Liver ◽  
Esterase Gene ◽  
Dose Dependent ◽  
Dependent Signaling Pathway

A pepper esterase gene (PepEST) that is highly expressed during an incompatible interaction between pepper (Capsicum annuum) and the anthracnose fungus Colletotrichum gloeosporioides has been previously cloned. Glutathione-S-transferase-tagged recombinant PepEST protein expressed in Escherichia coli showed substrate specificity for p-nitrophenyl esters. Inoculation of compatible unripe pepper fruits with C. gloeosporioides spores amended with the recombinant protein did not cause anthracnose symptoms on the fruit. The recombinant protein has no fungicidal activity, but it significantly inhibits appressorium formation of the anthracnose fungus in a dose-dependent manner. An esterase from porcine liver also inhibited appressorium formation, and the recombinant protein inhibited appressorium formation in the rice blast fungus, Magnaporthe grisea. Inhibition of appressorium formation in M. grisea by the recombinant protein was reversible by treatment with cyclic AMP (cAMP) or 1,16-hexadecanediol. The results suggest that the recombinant protein regulates appressorium formation by modulating the cAMP-dependent signaling pathway in this fungus. Taken together, the PepEST esterase activity can inhibit appressorium formation of C. gloeosporioides, which may result in protection of the unripe fruit against the fungus.

Sign in / Sign up

Export Citation Format

Share Document