scholarly journals Strawberry Anthracnose: Histopathology of Colletotrichum acutatum and C. fragariae

2002 ◽  
Vol 92 (10) ◽  
pp. 1055-1063 ◽  
Author(s):  
Kenneth J. Curry ◽  
Maritza Abril ◽  
Jana B. Avant ◽  
Barbara J. Smith
Keyword(s):  
Vascular Tissue ◽  
Light And Electron Microscopy ◽  
Hyphal Growth ◽  
Fungal Species ◽  
Colletotrichum Acutatum ◽  
Cortical Tissue ◽  
In Planta ◽  
Strawberry Anthracnose ◽  
Strawberry Cultivar ◽  
Germ Tubes

Ontogeny of the invasion process by Colletotrichum acutatum and C. fragariae was studied on petioles and stolons of the strawberry cultivar Chandler using light and electron microscopy. The invasion of host tissue by each fungal species was similar; however, each invasion event occurred more rapidly with C. fragariae than with C. acutatum. Following cuticular penetration via an appressorium, subsequent steps of invasion involved hyphal growth within the cuticle and within the cell walls of epidermal, subepidermal, and subtending cells. Both species of fungi began invasion with a brief biotrophic phase before entering an extended necrotrophic phase. Acervuli formed once the cortical tissue had been moderately disrupted and began with the development of a stroma just beneath the outer periclinal epidermal walls. Acervuli erupted through the cuticle and released conidia. Invasion of the vascular tissue typically occurred after acervulus maturation and remained minimal. Chitin distribution in walls of C. fragariae was visualized with gold-labeled wheat germ agglutinin. The outer layer of bilayered walls of conidia, germ tubes, and appressoria contained less chitin than unilayered hyphae in planta.

scholarly journals Improved Microassays Used to Test Natural Product-Based and Conventional Fungicides on Plant Pathogenic Fungi

Plant Disease ◽  
2008 ◽  
Vol 92 (1) ◽  
pp. 106-112 ◽  
Author(s):  
Maritza Abril ◽  
Kenneth J. Curry ◽  
Barbara J. Smith ◽  
David E. Wedge
Keyword(s):  
Natural Product ◽  
Fungal Growth ◽  
Pathogenic Fungi ◽  
Fungal Species ◽  
Colletotrichum Acutatum ◽  
Plant Pathogenic Fungi ◽  
Germination Inhibition ◽  
Germination And Growth ◽  
Germ Tubes

Seven important plant pathogenic fungi (Botrytis cinerea, Colletotrichum acutatum, C. fragariae, C. gloeosporioides, Fusarium oxysporum, Phomopsis obscurans, and P. viticola) valuable in screening fungicides were tested. Our procedure included washing conidia to reduce germination times, incorporating Roswell Park Memorial Institute 1640 as a medium of known composition, and using coverslips in the 24-well cell culture clusters to document the effect of fungicides on fungal morphology. The natural product-based fungicide, sampangine, a sampangine analog, 4-bromosampangine, plus seven conventional fungicides (benomyl, captan, cyprodinil, fenbuconazole, fenhexamid, iprodione, and kresoxim-methyl) were tested in vitro for their ability to inhibit germination and growth of the seven fungal species. Sampangine inhibited germination in all fungi except C. acutatum. Comparison of results of germination and morphology microbioassays with results of microtiter assays suggests that some fungicides stop fungal germination, whereas others only slow down fungal growth. We hypothesize that sampangine, except against C. acutatum, has the same physical mode of action, germination inhibition, as the conventional fungicides captan, iprodione, and kresoxim-methyl. 4-Bromosampangine caused morphological anomalies including excessive branching of germ tubes of C. fragariae and splaying and branching of germ tubes of B. cinerea.

scholarly journals In Silico Analyses of Rice Thionin Genes and the Antimicrobial Activity of OsTHION15 Against Phytopathogens

2019 ◽  
Vol 109 (1) ◽  
pp. 27-35
Author(s):  
Krissana Boonpa ◽  
Suparuk Tantong ◽  
Kamonwan Weerawanich ◽  
Pawinee Panpetch ◽  
Onanong Pringsulaka ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Stress Responses ◽  
In Silico ◽  
Pathogenic Bacteria ◽  
Hyphal Growth ◽  
In Planta ◽  
Recombinant Peptide ◽  
Plant Disease Control ◽  
Helminthosporium Oryzae ◽  
In Silico Analyses

Thionins are a family of antimicrobial peptides. We performed in silico expression analyses of the 44 rice (Oryza sativa) thionins (OsTHIONs). Modulated expression levels of OsTHIONs under different treatments suggest their involvement in many processes, including biotic, abiotic, and nutritional stress responses, and in hormone signaling. OsTHION15 (LOC_Os06g32600) was selected for further characterization based on several in silico analyses. OsTHION15 in O. sativa subsp. indica ‘KDML 105’ was expressed in all of the tissues and organs examined, including germinating seed, leaves, and roots of seedlings and mature plants, and inflorescences. To investigate the antimicrobial activity of OsTHION15, we produced a recombinant peptide in Escherichia coli Rosetta-gami (DE3). The recombinant OsTHION15 exhibited inhibitory activities toward rice-pathogenic bacteria such as Xanthomonas oryzae pv. oryzae and Pectobacterium carotovorum pv. atroseptica, with minimum inhibitory concentrations of 112.6 and 14.1 µg ml−1, respectively. A significant hyphal growth inhibition was also observed toward Fusarium oxysporum f. sp. cubense and Helminthosporium oryzae. In addition, we demonstrated the in planta antibacterial activity of this peptide in Nicotiana benthamiana against X. campestris pv. glycines. These activities suggest the possible application of OsTHION15 in plant disease control.

scholarly journals Bright-Field and Fluorescence Microscopic Study of Development of Erysiphe polygoni in Susceptible and Resistant Bigleaf Hydrangea

Plant Disease ◽  
2009 ◽  
Vol 93 (2) ◽  
pp. 130-134 ◽  
Author(s):  
Yonghao Li ◽  
Mark T. Windham ◽  
Robert N. Trigiano ◽  
Sandra M. Reed ◽  
James M. Spiers ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Hyphal Growth ◽  
Early Response ◽  
Resistance Mechanisms ◽  
Colony Development ◽  
Susceptible Cultivar ◽  
Bright Field ◽  
Erysiphe Polygoni ◽  
Infected Cells ◽  
Germ Tubes

Temporal development of Erysiphe polygoni and responses of bigleaf hydrangeas (Hydrangea macrophylla) to the fungal attack were investigated using bright-field and fluorescence microscopy. Conidia germinated 2 h after inoculation (HAI) and formed primary appressoria at the tip of the primary germ tubes within 4 HAI. Secondary germ tubes were initiated from primary appressoria or other parts of conidia 12 HAI. Hyphae developed through elongation of secondary germ tubes, and paired lateral appressoria were formed along hyphae within 2 days after inoculation (DAI). Conidiophores and conidia were formed 5 DAI. In the susceptible cultivar Nikko Blue and the resistant cultivar Veitchii, the fungus established a parasitic relationship, which was indicated by the formation of haustoria under primary appressoria and development of secondary germ tubes at 1 DAI. A hypersensitive response (HR) and accumulation of callose were detected in both resistant and susceptible cultivars at 3 DAI. Resistance to powdery mildew in Veitchii was evident by manifestation of early accumulation of callose, relatively high percentage of necrotic infected cells, and restricted colony development compared to the susceptible cultivar Nikko Blue. Restricting hyphal growth and sporulation by early response of callose accumulation and HR are important resistance mechanisms that could be used in screening hydrangeas for resistance to powdery mildew.

scholarly journals The Glycosylphosphatidylinositol Anchor Biosynthesis Genes GPI12, GAA1, and GPI8 Are Essential for Cell-Wall Integrity and Pathogenicity of the Maize Anthracnose Fungus Colletotrichum graminicola

2016 ◽  
Vol 29 (11) ◽  
pp. 889-901 ◽  
Author(s):  
Ely Oliveira-Garcia ◽  
Holger B. Deising
Keyword(s):  
Cell Wall ◽  
Posttranslational Modifications ◽  
Hyphal Growth ◽  
Transcript Abundance ◽  
Essential Genes ◽  
Colletotrichum Graminicola ◽  
In Planta ◽  
Vegetative Development ◽  
Cell Wall Rigidity ◽  
Gpi Transamidase

Glycosylphosphatidylinositol (GPI) anchoring of proteins is one of the most common posttranslational modifications of proteins in eukaryotic cells and is important for associating proteins with the cell surface. In fungi, GPI-anchored proteins play essential roles in cross-linking of β-glucan cell-wall polymers and cell-wall rigidity. GPI-anchor synthesis is successively performed at the cytoplasmic and the luminal face of the ER membrane and involves approximately 25 proteins. While mutagenesis of auxiliary genes of this pathway suggested roles of GPI-anchored proteins in hyphal growth and virulence, essential genes of this pathway have not been characterized. Taking advantage of RNA interference (RNAi) we analyzed the function of the three essential genes GPI12, GAA1 and GPI8, encoding a cytoplasmic N-acetylglucosaminylphosphatidylinositol deacetylase, a metallo-peptide-synthetase and a cystein protease, the latter two representing catalytic components of the GPI transamidase complex. RNAi strains showed drastic cell-wall defects, resulting in exploding infection cells on the plant surface and severe distortion of in planta–differentiated infection hyphae, including formation of intrahyphal hyphae. Reduction of transcript abundance of the genes analyzed resulted in nonpathogenicity. We show here for the first time that the GPI synthesis genes GPI12, GAA1, and GPI8 are indispensable for vegetative development and pathogenicity of the causal agent of maize anthracnose, Colletotrichum graminicola.

scholarly journals Zeamatin-Like Protein (ZLP) Gene is Associated with Resistance against A. niger in Maize (Zea mays L.)

2016 ◽  
Vol 49 (2) ◽  
pp. 29-39
Author(s):  
A.M. Sajjad ◽  
T. Bahsir ◽  
S. Saeed ◽  
M. Iqbal ◽  
S. Islam ◽  
...  
Keyword(s):  
Zea Mays ◽  
Zea Mays L ◽  
Hyphal Growth ◽  
Antimicrobial Activities ◽  
Fungal Species ◽  
High Rate ◽  
Sds Page ◽  
Pathogenesis Related ◽  
Enhanced Expression ◽  
Related Proteins

Abstract Maize (Zea mays L.) constitutes one of the most important crops worldwide with multi-billion dollar annual revenue. The plant is however a good substrate for growth, development and activity of filamentous fungi. A large number of fungal species causes spoilage and accumulation of mycotoxins. Plants restrict the hyphal growth by producing pathogenesis related proteins. So far 17 groups of such proteins are identified. PR-5 group comprises of the thaumatin-like proteins (TLPs), which have diverse modes of actions and act at various stages of fungal attack. Zeamatin-like protein (ZLP) is a member of TLPs, which is basically localized in seeds with enhanced expression during physiological growth and cellular differentiation. However a basal quantity is found in the leaves of many crop plants. Here we report the response of maize plant tissues against A. niger inoculation by measuring the variation in expression profile of a zeamatin-like gene. Conventional PCR coupled with RT-qPCR identifies a significant change in the expression magnitude of ZLP in pre- and post-inoculated plant samples. SDS-PAGE, followed by antimicrobial activities against A. niger, E.coli, P. aeruginosa, B. cereus, S. aureus and S. typhimurium, however, do not register a direct relationship with enhancement in gene expression. It is in line with the fact that response to pathogenesis in plants is a multigenic activity involving a series of responsible/induced genes. The assay developed is useful in primary sorting out of the maize hybrids with respect to their resistance against Aspergillus spp., especially in areas with high rate of incidence of fungal pathogenesis.

Behaviour of Phytophthora cinnamomi Zoospores on Roots of Australian Forest Species

1979 ◽  
Vol 27 (6) ◽  
pp. 679 ◽  
Author(s):  
J Hinch ◽  
G Weste
Keyword(s):  
Vascular Tissue ◽  
Root Zone ◽  
Phytophthora Cinnamomi ◽  
Host Susceptibility ◽  
Forest Species ◽  
Native Forests ◽  
Species Specific ◽  
Germ Tubes ◽  
Root Axis

Twenty-three species from Australian native forests were examined in a comparative assay of the chemotaxis of zoospores of Phytophthora cinnamomi towards their roots. Zoospores were attracted to all species tested when within 3-4 mm from the roots. Attraction to wounds and cut ends of roots was also observed. The chemotaxis was neither species-specific nor host-orientated. The root zone which attracted most zoospores was the region of elongation for most species, but this varied and is described and illustrated for the different species. Encysted zoospores produced one and occasionally two germ tubes which were normally orientated towards the root axis. Subsequent penetration of epidermis, cortex and vascular tissue was observed and, like the chemotaxis and chemotropy, was not related to host susceptibility.

Penetration and colonization of resistant and susceptible Apium graveolens by Fusarium oxysporum f.sp. apii race 2: callose as a structural response

1988 ◽  
Vol 66 (12) ◽  
pp. 2385-2391 ◽  
Author(s):  
C. M. Jordan ◽  
R. M. Endo ◽  
L. S. Jordan
Keyword(s):  
Fusarium Oxysporum ◽  
Host Cell ◽  
Cell Walls ◽  
Vascular Tissue ◽  
Periodic Acid ◽  
Light And Electron Microscopy ◽  
Structural Response ◽  
Aniline Blue ◽  
Apium Graveolens ◽  
Race 2

Root apices of Apium graveolens L. resistant and susceptible to race 2 of Fusarium oxysporum f.sp. apii (R. Nels. & Sherb.) were studied at various times after inoculation, using light and electron microscopy to determine structural response(s) of the hosts during penetration and colonization by the pathogen. Penetration was intercellular and intracellular and involved mechanical and enzymatic mechanisms. At the onset of penetration, the host cell walls manifested fluorescence, induced with either aniline blue or sirofluor, at the point of penetration. The fluorescent area was more intense and larger in the resistant host. Fluorescence disappeared with time. After incubation with β-1,3 glucanase fluorescence disappeared, indicating β-1,3 polysaccharide (probably callose) presence. Callose deposits were 2 and 3 times greater in the epidermis and 4 and 9 times greater in the cortex of the resistant than in two susceptible hosts, respectively. Hyphal counts in the cortex of the resistant host were 50% fewer than in the susceptible hosts. Increased callose deposition on host cell walls was associated with reduced colonization. Callose formed in vascular tissue as the fungus colonized it. Callose detection with sirofluor was more sensitive; background fluorescence common with aniline blue without periodic acid – Schiff's reagent pretreatment was absent.

Characterization of an antifungal soil bacterium and its antagonistic activities againstFusariumspecies

2003 ◽  
Vol 49 (4) ◽  
pp. 253-262 ◽  
Author(s):  
Yiu-Kwok Chan ◽  
Wayne A McCormick ◽  
Keith A Seifert
Keyword(s):  
Bacillus Subtilis ◽  
Culture Filtrate ◽  
Fusarium Species ◽  
Hyphal Growth ◽  
Antagonistic Activity ◽  
Plant Diseases ◽  
Ear Rot ◽  
In Planta ◽  
Head Blight

Bacteria were isolated from a cultivated soil and screened for antagonistic activity against Fusarium graminearum, a predominant agent of ear rot and head blight in cereal crops. Based on its in vitro effectiveness, isolate D1/2 was selected for characterization and identified as a strain of Bacillus subtilis by phenotypic tests and comparative analysis of its 16S ribosomal RNA gene (rDNA) sequence. It inhibited the mycelial growth of a collection of common fungal phytopathogens, including eight Fusarium species, three other ascomycetes, and one basidiomycete. The cell-free culture filtrate of D1/2 at different dilutions was active against macroconidium germination and hyphal growth of F. graminearum, depending on the initial macroconidium density. It induced the formation of swollen hyphal cells in liquid cultures of this fungus grown from macroconidia. A bioassay also demonstrated that D1/2 offered in planta protection against the damping-off disease in alfalfa seedlings caused by F. graminearum, while the type strain of B. subtilis was ineffective. Hence, B. subtilis D1/2 or its culture filtrate has potential application in controlling plant diseases caused by Fusarium.Key words: antifungal activity, Bacillus subtilis, biological control, biopesticide, Fusarium species.

scholarly journals A Pattern Recognition Tool for Quantitative Analysis of In Planta Hyphal Growth of Powdery Mildew Fungi

2005 ◽  
Vol 18 (9) ◽  
pp. 906-912 ◽  
Author(s):  
U. Seiffert ◽  
P. Schweizer
Keyword(s):  
Growth Rate ◽  
Pattern Recognition ◽  
Quantitative Analysis ◽  
Powdery Mildew ◽  
Growth Rates ◽  
Fungal Pathogens ◽  
Hyphal Growth ◽  
Blumeria Graminis ◽  
In Planta ◽  
Powdery Mildew Fungi

The development of fungal pathogens can be quantified easily at the level of spore germination or penetration. However, the exact quantification of hyphal growth rates after initial, successful host invasion is much more difficult. Here, we report on the development of a new pattern recognition software (HyphArea) for automated quantitative analysis of hyphal growth rates of powdery mildew fungi on plant surfaces that usually represent highly irregular and noisy image backgrounds. By using HyphArea, we measured growth rates of colonies of the barley powdery mildew, Blumeria graminis f. sp. hordei, on susceptible and induced-resistant host plants. Hyphal growth was not influenced by the resistance state of the plants up to 48 h postinoculation. At later time points, growth rate increased on susceptible plants, whereas it remained restricted on induced-resistant plants. This difference in hyphal growth rate was accompanied by lack of secondary haustoria formation on induced-resistant plants, suggesting that induced resistance in barley against Blumeria graminis is caused mainly by reduced penetration rates of primary as well as secondary appressoria leading, finally, to fewer and lessdeveloped fungal colonies. No evidence was found for reduced nutrient-uptake efficiency of the primary haustoria in induced-resistant leaves, which would be expected to have resulted in reduced hyphal growth rates during the first 48 h of the interaction.

scholarly journals First Report of Colletotrichum acutatum in Blueberry Plants in Spain

Plant Disease ◽  
2001 ◽  
Vol 85 (12) ◽  
pp. 1285-1285 ◽  
Author(s):  
C. Barrau ◽  
B. de los Santos ◽  
F. Romero
Keyword(s):  
Pink Salmon ◽  
Morphological Characteristics ◽  
Vaccinium Corymbosum ◽  
Fungal Species ◽  
Colletotrichum Acutatum ◽  
Enzyme Linked Immunosorbent Assay ◽  
Conidial Suspension ◽  
First Report ◽  
Small Areas ◽  
Leaf Tissues

An anthracnose disease was observed affecting leaves of high-bush blueberry plants (Vaccinium corymbosum L. ‘Sharpblue’) in small areas within two production fields in Huelva Province of Andalucía, in southwestern Spain. The first symptoms observed in late spring were circular, necrotic lesions, red to salmon in color, and ranging from 3 to 20 mm in diameter. Later, lesions became salmon colored in the center with a brilliant red halo. Fungal isolations were made from the lesions. Infected tissues were surface-disinfected in 1% sodium hypochlorite for 1 min, blotted dry on sterile filter paper, and plated on 2% water agar. The plates were incubated at 25°C for 5 to 10 days. Fungal colonies isolated from the tissues were transferred to potato dextrose yeast agar (PDYA). Only one fungal species was consistently isolated from affected leaf tissues and was identified as Colletotrichum acutatum J.H. Simmonds based on morphological characteristics (2) and enzyme-linked immunosorbent assay (1). Colonies of the fungus on PDYA showed a white-to-gray dense mycelium covered with salmon-colored spore masses. The reverse of the plates was a pink-salmon color. Colony diameter on PDYA averaged 50 mm after 7 days at 25°C. Conidia were hyaline, aseptate, fusiform to cylindrical, and 12.5 × 3.2 μm. Inoculation of leaves and fruits of blueberry cv. Misty with a conidial suspension (106 conidia per ml) of C. acutatum produced lesions on the leaves and fruits similar to those observed on diseased plants in the field. The pathogen was isolated from lesions on inoculated plants. To our knowledge, this is the first report of C. acutatum in high-bush blueberry plants in Spain. References: (1) T. A. Cooke et al. EPPO Bull. 25:57, 1995. (2) B. C. Sutton. The Coelomycetes. CMI, Kew, England, 1980.

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