Radial Growth Of Fungus Research Articles

Optimization of in vitro and in vivo antifungal effects of trehalose coating included Artemisia sieberi essential oil on mulberry (Morus alba var. nigra) fruits using the hybrid RSM-GRA method.

Mulberry is prone to microbial contamination due to mechanical damage during the harvesting. This study aimed to determine, and optimize fruit microbial loads, and in vitro and in vivo antifungal effects of trehalose coating including Artemisia sieberi essential oil on mulberry fruits using hybrid RSM-GRA. Among all treatments, dropping height of 1.2m, storage regimes of 3days, and concentration of 1%, resulted in a pH of 3.188, a moisture content of 89.193%, a dry matter content of 10.807%, a total soluble solids (TSS) of 8.537°brix, an radial growth of fungus (RGF) of 1.193cm for purple mulberry fruit, and dropping height of 0.6m, storage regimes of 2days, and concentration of 1% for black mulberry fruit, leading to a pH of 3.182, a moisture content of 84.80%, a dry matter content of 15.230%, a TSS of 9.690°brix, an RGF of 1.460cm were the best conditions for mulberry fruit.

Impact of water activity on the radial growth of fungi in a dairy environment

Filamentous fungi are used in the dairy industry as adjunct cultures in fermented products, but can also lead to food spoilage, waste and economic losses. The control of filamentous fungi with abiotic factors contributes to longer food shelf life and prevention of fungal spoilage. One of the main abiotic factors for controlling fungal growth in foods is water activity (aw). This study aimed to evaluate radial growth as a function of aw for sixteen fungal adjuncts and/or spoilers isolated from dairy products or a dairy environment. Glycerol (a non-ionic compound) and sodium chloride (NaCl, an ionic compound) were used to adjust the aw of culture media. This study showed significant diversity in the responses of the tested fungal strains as a function of medium aw. The growth response of Penicillium bialowiezense and Sporendonema casei was binary, with no clear decrease of growth rate until the growth limit, when the aw was reduced. For the strains of Bisifusarium domesticum, Mucor circinelloides and Penicillium camemberti, a decrease of aw had the same impact on radial growth rate regardless of the aw belonging to their growth range. For the strains of Aspergillus flavus, Cladosporium herbarum, Geotrichum candidum, Mucor lanceolatus, Penicillium expansum, Penicillium fuscoglaucum, Penicillium nalgiovense, Paecilomyces niveus, Penicillium roqueforti, Penicillium solitum and Scopulariopsis asperula, the impact of a decrease in aw was more pronounced at high aw than at low aw. A mathematical model was suggested to describe this impact on the radial growth rate. For all tested species, radial growth was more sensitive to NaCl than glycerol. The ionic strength of NaCl mainly explains the difference in the effects of the two solutes.

Jasmonic Acid Induced Systemic Resistance in Infected Cucumber by Pythium aphanidermatum

Damping-off disease of cucumber is one of the most destructive diseases of cucumber in worldwide. In this work, the potential of jasmonic acid (JA) for induce resistant against damping off disease was investigated. The effect of JA on activity of Polyphenol oxidase (PPO), Peroxidase (PO) and Catalase (CAT) enzymes and total phenol was assayed by spectrophotometric method. Expression level of three plant defense genes as Lipoxygenase, Cupi4 and Phenylalanine ammonia-lyase genes was analyzed using qRT-PCR method. Drop-plate method was used to assay inhibitory effect of JA on radial growth of fungi. Exogenic application of JA decreased disease severity in the infected plants but did not inhibit mycelia growth on solid medium compared to control. Our results showed that JA application substantially increased the activity of oxidative enzymes at different concentration. The highest enzyme activity was recorded after 48 hours post infection (hpi) at a concentration of 400 mg L-1 of JA. Gene expression analysis revealed that JA is differentially able to increase the mRNA transcripts of all tested genes at 48 hpi. The expression level of Cupi4 gene was higher than the other genes in treated plants. Induced systemic resistance by JA was mediated through an enhanced expression of ISR marker genes and increase of antioxidant enzymes activity. Based on these results, we suggest that exogenic application of JA could be considered as plant resistance inducer.

Effect of pathogenic, cultural variability and chemical management of Sclerotium rolfsii

Among the ten isolates of Sclerotium rolfsii , collected from major chilli growing areas of Uttar Pradesh found that the pathogenic variability of the pre germination disease incidence was highest (21.20%) in isolate of district Fatehpur and was lowest (9.5%) in Raibarelly isolates. The cultural variability on the radial growth of fungus and sclerotial production indicated that the radial growth of fungus was maximum in the case of SR1 (83.0 mm) isolate, followed by SR9 (82.00 mm) isolate which were statistically at par with each other. The colony characters was excellent, fluffy in SR1, SR2, SR3, SR4, SR8, SR9 and SR10 isolates and compact in isolates of SR5, SR6 and SR7. In vitro studies revealed that the fungicides like Taqat, Hexaconazole, Propiconazole, Tricyclazole, Copper-oxychloride and Vitavax were most effective against the pathogen. The effect of fungicides as seed treatment revealed Taqat and Hexaconazole were found most effective in seed germination (92.8 and 87.5%), respectively and minimum in disease incidence (5.3 and 7.1%), respectively.

Identification of Causative Pathogen of Flower Bud Wilt Disease in Dendrobium sp. and In-vitro Growth Inhibition by Medicinal Plant Extracts

Aims: The aim of this study was to isolate and identify the causal agent of wilting of flower buds of Dendrobium orchid in Sri Lanka and to search for environmental friendly control measures for flower bud wilt disease as a possible alternative to synthetic fungicides. Study Design: The experiment was conducted using a completely randomized design. Place and Duration of Study: Faculty of Agricultural Sciences, Sabaragamuwa University of Sri Lanka from June 2013 to May 2014. Methodology: The causal fungus isolated from the diseases plant was identified based on their morphology, pathogenicity and ribosomal DNA spacer sequences. The media amended with methanol plant extracts of different concentrations (25%, 12.5%, 6.25%, 3.125%) of tested medicinal plants were inoculated with mycelia discs (4 mm diameter) taken from the advancing edges of 10 day-old pure cultures ofisolated fungus andincubated for 7 days. The fungicidal activities of MIC of methanol extracts were studied after immersing fungal blocks in solution for 1, 3, 6, 12 and 24 hours respectively. The media amended with methanol and recommended Original Research Article Dissanayake; IJPSS, 4(2): 132-139, 2015; Article no.IJPSS.2015.014 133 fungicide were considered as negative and positive control respectively. Results: Based on morphological characteristics and rDNA spacer sequences, isolates were identified as F. proliferatum. This is the first record of flower bud wilt disease in Dendrobium sp. in Sri Lanka. Results showed that radial growth of fungus was significantly impaired (P<0.05.) by the addition of the extracts in the culture medium used. The test fungus differed in their reaction to the different extracts but on the whole, growth inhibition increased with the concentration of each extract. The most active extracts, 25% methanol extracts from sweet flag shows a marked effect with inhibition values of 77% against F. proliferatum whereas those from wild basil inhibited the growth by 55%. Out of four plants extract screened, sweet flag showed more than 80% fungal inhibition after 12 hour immersion and other extracts could not exceed 60% inhibition after any exposure time. Conclusion: The present study concludes disease found in Dendrobium orchid was caused by F. proliferatum and Methanol extracts of Sweet flag contain antifungal constituents for the control of F. proliferatum.

THE INFLUENCE OF ULTRAVIOLET LIGHT ON PATHOGENICITY OFENTOMOPATHOGENIC FUNGUS BEAUVERIA BASSIANA (BALSAMO)VUILLEMIN TO THE EUROPEAN CORN BORER, OSTRINIA NUBILALIS HBN.(LEPIDOPTERA: CRAMBIDAE)

The influence of different doses of ultraviolet (UV) light on the pathogenicity of entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin to the European corn borer, Ostrinia nubilalis Hbn., and radial growth of fungus was studied in laboratory conditions. The suspensions of B. bassiana isolate SK99 were exposed to UV light. Four different doses of UV light were used in the experiment. The distance between exposed suspensions and UV light source was 0.3 m. Exposure duration was 15, 30, 45 and 60 minutes (as A, B, C and D variants). Control variant SK99 and obtained variants SK99A, SK99B, SK99C and SK99D were cultivated 21 days on Sabourard-dextrose agar. The larvae of O. nubilalis were infected with dry powder consisted of mycelia and spores from fungus cultures. During 10 days, the mortality of infected larvae was evaluated. It was ascertained that UV light exposition significantly influenced the mortality effect of B. bassiana isolates to O. nubilalis larvae. Variant SK99C showed the highest level of infectivity. Radial growth of UV variants was slower with rising time of exposure. The best ability to grow possessed non-irradiated isolate SK99 and the worse variant SK99D. The difference between these two variants was significant.

Photo‐induced fungicidal activity elicited by naturally occurring thiophene derivatives

AbstractPhoto‐induced fungitoxicity was observed in Alternaria alternata, Aspergillus niger, Cladosporium variabile, Colletotrichum sp., Rhizopus nigricans, Pythium aphanidermatum, and Saprolegnia sp., elicited by 5‐(but‐3‐en‐l‐ynyl)‐2,2′‐bithienyl, 2,2′: 5′,2″‐terthienyl, and 2‐chloro‐4‐[5‐(penta‐1,3‐diynyl)‐2‐thienyl]but‐3‐ynyl acetate in the presence of near ultraviolet (u.v.) radiation (320–380 nm). Conidiogenesis in A. niger, and sporangiosporogenesis in R. nigricans were depressed on media treated with 2,2′: 5′,2″‐terthienyl and irradiated with near u.v. light. Radial growth of mycelia of all fungi tested was dramatically reduced by all three compounds in the presence of near u.v. light. The viability of conidia of A. niger, and R. nigricans was unaffected by 2,2′: 5′,2″‐terthienyl, both in the dark and in near u.v. light. Newly emergent germ‐tubes were most sensitive to toxicity mediated by u.v. light. The oomycetous fungi tested were the most sensitive to the photo‐activated toxicity generated by the three compounds used. The results indicate that ED50 values are dependent upon the species and the presence or absence of near u.v. light. Dramatically lowered ED50 values were always observed in all systems treated with near u.v. light. The dose of near u.v. light used had no effect on the radial growth of fungi in the absence of the three compounds.