Penetration Of Fungal Hyphae Research Articles

Mitigation of Fusarium Wilt Disease of Vicia faba Using Artemisia monosperma Extract

The antifungal activity of Artemisia monosperma aqueous extracts against Fusarium solani. sp. Phaseoli the causal agent of Vicia faba wilt and its ability in inducing disease resistance were studied in vivo using seed-soaking treatment before sowing. Plants were harvested at vegetative and flowering stages after sowing. Results showed that growth, yield parameters and phytohormone contents were markedly inhibited in bean plants in response to Fusarium wilt disease, whereas lipid peroxidation and the contents of non-enzymatic and enzymatic antioxidants were increased as compared with healthy control plants. Moreover, presoaking in A. monosperma extract increased all the mentioned parameters and decreased lipid peroxidation in both healthy and infected plants. Intracellular penetration of fungal hyphae was also observed. Moreover, transmission sections of roots showed other effects of Fusarium infection. Meanwhile, A. monosperma extract could alleviate the harmful effects of Fusarium infection via improving the above mentioned studied parameters. From the obtained results, it can be concluded that A. monosperma extract as a biocontrol agent played an important role in enhancing plant resistance against Fusarium wilt disease of bean plants.

Investigating the effect of white-rot hymenomycetes biodegradation on basal stem rot infected oil palm wood blocks: Biochemical and anatomical characterization

Basal Stem rot (BSR) disease of oil palm caused by Ganoderma boninense is one of the major obstacle in oil palm production. The root contact with unattended infected debris left in the plantations during replanting is known to be the primary source of infection spread. Abiding with the law, potentially effective technique of managing Ganoderma infected oil palm debris is deemed necessary because of the zero-burning policy in Malaysian oil palm plantations. The wood degradation abilities of four white-rot hymenomycetes were assessed using oil palm blocks obtained from healthy and diseased portions of oil palm trunks infected with G. boninense. In general, out of four white-rot hymenomycetes, Pycnoporus sanguineus FBR secreted a significantly (P≤0.05) greater quantity of oxidative enzymes than that secreted by the Grammothele fuligo strains. The ability of G. fuligo ST2 and P. sanguineus FBR to secrete amylase enzymes has been well documented and the enzyme profiles were about 4.5-fold (G. fuligo ST2) and 2.8-fold (P. sanguineus FBR) higher in samples collected at day 120 than at day 30 of biodegradation, supported with Fourier transform infrared (FTIR) spectra. The crystallinity ratio was found to increase in the middle of decay process, owing to the preferential degradation of non-crystalline lignins and hemicelluloses by both strains. Syringyl (S)-lignin units were favorably degraded than guaiacyl (G)-lignin units by both strains, resulting in a decreased S/G ratio in the diseased portions, at the end of decay process. Scanning electron microscopy (SEM) revealed that penetration of fungal hyphae within the wood vessels and the parenchymal tissues with boreholes, resulting in the loosening of the parenchymal tissue and wood rays. Based on the lignocellulolytic enzymes production and the level of degradation, P. sanguineus FBR and G. fuligo ST2 regarded as the best bio-degraders of G. boninense colonized wood blocks. This study provides the novel insight on understanding the biochemical and anatomical changes induced by white-rot hymenomycetes during biodegradation of oil palm wood blocks with an ultimate aim of reducing the Ganoderma inoculum under heavy BSR infection pressure in ecofriendly manner.

Oxalate biofilm formation in mural paintings due to microorganisms – A comprehensive study

Oxalate film formation is a pathology that often occurs in mural paintings and may result from the concomitant action of microorganisms and environmental conditions.Low Choir of the Convent of Nossa Senhora da Saudação (Portugal) has mural paintings with an extraordinary beauty, which over time have been suffered polychromy degradation and biofilm formation, presenting an ideal case study to investigate the role and impact of microorganisms in the biodeterioration process.Bacterial populations, filamentous fungi belonging to the genera Cladosporium, Penicillium, Nectria and yeast strain of the genera Rhodotorula were isolated from these wall paintings. The penetration of fungal hyphae in the microstructure of mortars, observed by scanning electron microscopy, seems to be responsible for cracking and detachments in some areas of the painting. The study revealed that the veils on the surface of the paintings are essentially oxalates and that these biofilms are caused by metabolic activity of bacterial communities. Furthermore, the colour alteration of green areas due to microorganisms was detected by Raman microscopy, in real samples and under in vitro conditions, being the result of the metabolic activity of microorganisms present on the paintings, which promote calcium oxalates formation over the malachite paint layers.

The Infection Processes of Sclerotinia sclerotiorum in Basal Stem Tissue of a Susceptible Genotype of Helianthus annuus L.

Sunflower, Helianthus annuus L., is a major oil seed crop widely cultivated throughout the globe. White mold, caused by necrotrophic pathogen Sclerotinia sclerotiorum (Lib.) de Bary, is a common and widespread pathogen of sunflower. The infection process of S. sclerotiorum was studied in the stem base of infected host tissues by light microscopy and Hemi-thin sectioning techniques. Host-pathogen interactions were examined at the plant surface and cellular level of a susceptible genotype (C146), 12, 24 and 48 h of post inoculation. The results showed that the appressoria were formed and the hyphal strands branched upon contact of pathogen with the host surface. Moreover a direct penetration of fungal hyphae was observed through the cuticle within 12h of inoculation. Microscopic observation of inoculated tissues after 24 hours revealed that fungal hyphae have developed both inter- and intra-cellular layer. Moreover, the fungal hyphae growth was incremental among and inside the host cells. The host cells were completely colonized by fungal mycelium 48 hour after inoculation, leading to a tissue collapse. The hyphae invaded the dead host tissues and emerged from the host tissue after extensive colonization. The present study has detailed the infection processes and pathogen development both at plant surface and inside the host tissues. The results of this study will be useful for engineering of disease-resistant genotypes and development of markers for screening pathogen resistance individuals.

Histological investigation of infection processes of Discula destructiva on leaves of Cornus florida

The infection process of Discula destructiva Redlin on Cornus florida L. leaves was studied using histological and microscopic techniques. Penetration of fungal hyphae through natural openings and wounds was not observed, while direct penetration without appressorium formation was demonstrated 3 days after inoculation (DAI). Leaves inoculated with D. destructiva developed symptoms of dogwood anthracnose after 7 to 8 days. At 8 DAI, hyphae were observed in aggregations located between the cuticle and epidermis and also growing intracellularly towards epidermal, palisade, parenchymal and spongy mesophyll cells. At 16 DAI, typical chlorotic and necrotic halos, with a red to purple external border, were formed on the inoculated leaves. Within leaf tissues, at 16 DAI, chloroplasts were intact but decompartmentalized and infection sites were clearly defined. Sporulation and ruptured acervuli (cuticle ruptured and spores released) were first detected at 20 DAI, and had fully developed to rupture the plant cuticle on both adaxial and abaxial leaf surfaces by 24 DAI.

In vitro expression of resistance responses to Seiridium species in micropropagated shoots of Cupressus sempervirens and Chamaecyparis lawsoniana

Wounded and nonwounded micropropagated shoots of Cupressus sempervirens and Chamaecyparis lawsoniana were inoculated in vitro with the canker-causing pathogens Seiridium cardinale (Wag.) Sutton & Gibson, Seiridium cupressi (Guba) Boeswinkel and Seiridium unicorne (Cke & Ell.) Sutton. Seiridium cardinale was significantly more pathogenic on Cupressus sempervirens than on Chamaecyparis lawsoniana (Murr.) Parlatore, irrespective of the presence of wounds on the shoots. On wounded shoots, both S. cupressi and S. unicorne caused significantly larger lesions on Chamaecyparis lawsoniana than on Cupressus sempervirens by 20 days after inoculation. Superficial wounding of shoots prior to inoculation caused a significant increase in the lengths of lesions and numbers of shoots girdled by the pathogens on both hosts. These results broadly correlate with known virulence of the three pathogens on these two host tree species in field and glasshouse tests. Using histological methods, penetration of fungal hyphae through stomatal pores of both shoots and leaves into the substomatal cavity and the mesophyll space was observed. Penetration directly through the cuticle was also seen. Defence-related responses, including accumulation of oxidized polyphenols compounds and deposition of lignin and suberin in cell walls, were detected in inoculated tissues. These responses occurred predominantly in the epidermis, including stomatal guard cells, and the hypodermis and were particularly marked in Chamaecyparis lawsoniana inoculated with S. cardinale. The possible utility of these methods in the study and detection of host genotypes resistant to Seiridium spp. is discussed. Key words: Seiridium, Cupressus, Chamaecyparis, micropropagation, in vitro inoculation, defence.