Oatmeal Agar Medium Research Articles

Association between microsatellite markers and rice response to the rice blast pathogen Magnaporthe oryzae in selected Zambian rice genotypes

Magnaporthe oryzae, the rice blast disease pathogen is estimated to cause losses of up to 30% in rice production worldwide, yet its impact on rice production in Zambia remains unknown. Symptomatic rice leaf tissue collected from rice fields in Mongu District of Zambia was cultured on oatmeal agar medium and fungal colonies were purified and identified through leaf lesions and conidia using published keys. An M. oryzae isolate from this study was used to challenge twenty-eight selected Zambian rice genotypes to determine their responses to infection with the pathogen estimated by lesion numbers and sizes. Twelve of the genotypes (42.8%) were highly resistant (HR) with 1 to 2 lesions per cm2, 6 (21.4%) were moderately resistant with mean lesion numbers of 3 to 4 per cm2 while 10 (35.7%) were susceptible with lesion numbers above 5 per cm2 of leaf tissue. Polymerase chain reaction (PCR)-amplification of rice genomic DNA extracted from the 28 genotypes using selected microsatellite marker primers revealed a moderate genetic diversity with three of them showing significant genetic diversity. Allelic diversity among the selected genotypes was also confirmed from a calculated mean polymorphic information content of 0.8. A correlation between 8 of the microsatellite markers in some of the rice genotypes and their resistance response to M. oryzae was also established. Results show that some of the analysed rice genotypes have a significant potential for use as a genetic resource in breeding for varieties that are resistant to the rice blast pathogen for Zambian farmers.

Cultural and morphological characterisation of Colletotrichum fragrans of dracaena using various nutrient sources along with fungicide sensitivity tests

Dracaena, is an ornamental plant which helps in air purification. The foliage is damaged by innumerable diseases. Various carbon containing media viz. Potato dextrose agar, Peptone salt agar, Czepek’s Dox Agar, dextrose in Czepek’s Dox Agar medium was replaced by the same amount of sucrose and lactose and Oat meal agar was used to study the radial growth of Colletotrichum fragrans from Dracaena. Among these six carbon media, the most effective medium for its rapid growth was Peptone salt agar medium. Also, the morphological characters differed with change in media constituents, wherein Oat meal agar medium was found to be effective for the production of acervuli, conidia, setae of higher dimensions. Bioassay was conducted using four fungicides viz. Blitox, Mancozeb, Chlorothalonil and Difenoconazole with six different concentrations, Difenoconazole with EC50 value 299.2µ/ml gave best results. Also, in-vivo studies confirmed that Difenoconazole could inhibit the diseased lesion most effectively than others.

A New Record of Epicoccum draconis Isolated from the Soil in Korea

A fungal isolate US-18-11 was isolated from the soil in Uiseong, Korea. The mycelium growth measured after 7 days of incubation at 22℃ on malt extract agar (MEA) and oatmeal agar (OA) media was 42-43 mm and 41-44 mm in diameter, respectively. The fungal colony formed white to dull green aerial mycelia that were floccose with regular margins and olivaceous black with leaden gray patches on the reverse side. The conidia were hyaline to brown in color, ellipsoidal to ovoid, guttulate, abundant, globose, solitary, or confluent measuring 3.2-7.2×1.1-2.3 μm. A BLAST search of the large subunit (LSU), internal transcribed spacer (ITS) region, second largest subunit of DNA-directed RNA polymerase II (RPB2) and β-tubulin (TUB2) gene sequences revealed that the isolate US-18-11 has similarities of 99, 100, 97, and 99% with those of Epicoccum draconis CBS 186.83, respectively. A neighbor-joining phylogenetic tree constructed based on the concatenated dataset of above-mentioned sequences showed that isolate US-18-11 clustered with Epicoccum draconis CBS 186.83 in the same clade. Based on the results of morphological, cultural, and phylogenetic analysis, the isolate US-18-11 was identical to the previously described E. draconis CBS 186.83. To our knowledge, this is the first report of E. draconis in Korea.

Performance variation in growth and sporulation of isolates of Alternaria alternata Fr. Keissler causing blight disease in Mulberry

Mulberry Alternaria blight (Alternaria alternata) is one of the foliar devastating diseases and reduces leaf quality and yield. Studying the cultural characters of the pathogen is the first and most important basic step in identification process. The results of cultural studies revealed that PDA was the best medium for supporting the good radial growth of the isolate Aa-1, Aa-2, Aa-4 and Aa-7 with the maximum radial growth of 90.00 mm after ten days of inoculation. Whereas, isolate Aa-2 and Aa-6 yielded maximum growth of 90 mm in Sabouraud’s dextrose agar medium and isolate Aa-8 and Aa-9 in oat meal agar medium. Maximum growth (90 mm) in corn meal agar (Aa-7) and in Richards synthetic agar medium isolate Aa-4, Aa-6 and Aa-10 recorded good growth. Dry weight of mycelium of the different isolates A. alternata studies revealed that isolate Aa-3 showed maximum dry mycelial weight of the fungus noticed in Host leaf extract broth (998.71 mg) which was followed by Isolate Aa-2 (997.93 mg) and Isolate Aa-5 (997.4mg) in Sabouraud’s dextrose broth. Very good sporulation of the Isolate Aa-1 on Potato dextrose broth, Host leaf extracts broth, Oat meal agar broth and Corn meal broth was recorded. The Potato broth also supported good sporulation of three isolates viz: Aa-1, Aa-5 and Aa-9 whereas, by Host leaf extract broth and corn meal broth supported good sporulation of Isolate Aa-4 and Aa-5 respectively.

Physiological Studies of Myrothecium Roridum: An Inciting Agent of Myrothecium Leaf Blight in Cotton

Background: Cotton is one of the most important cash crops in India. It is also called as “White gold” because of its agricultural as well as industrial importance. Myrothecium leaf blight is an emerging disease in cotton which is growing consistently throughout the country and has been reported to cause significant losses in major cotton growing tracts of odisha. Considering the importance of the disease, the present investigation has been taken up to study the physiology of the fungus. Methods: An experiment was conducted in-vitro during 2016-18 to investigate the effect of temperature and pH on the growth of M. roridum. Seven different nutrient media viz. Potato Dextrose Agar (PDA) medium, Potato Sucrose Agar (PSA) medium, Host Leaf Extract Agar (HEA) medium, Potato Carrot Agar (PCA) medium, Czapek’sdox Agar (ZA) medium, Richard’s Agar (RA) medium and Oat meal agar medium (OMA) were tested under in-vitro conditions to ascertain a suitable medium for the growth of M. roridum. Result: The investigation in laboratory conditions has revealed that out of seven nutrient media tested, maximum radial growth was recorded in Potato Sucrose Agar (PSA) with an average radial growth of diameter 76.06 mm and the least growth was recorded on Richard’s Agar with a diameter of 23.66 mm. The growth of the fungus was observed to be maximum at a temperature of 28oC with a diameter of 61.09 mm and the minimum average growth of 17.36 mm was recorded at 36oC. Studies on pH revealed that that the fungus grows well in neutral and slight alkaline medium (6.5 - 8.0).

Effects of <italic>Tulasnella</italic> sp. S7 and its extract on <italic>Dendrobium officinale</italic> seed germination

Orchidaceae seeds are tiny, without an endosperm. In nature, seed germination depends on symbiotic fungi for nutrients. In symbiotic culturing with seeds of the orchid Dendrobium officinale on oatmeal agar (OMA) medium, Tulasnella sp. S7 promotes seed germination. This study investigated the field application effects of S7 on seed germination of D. officinale by using S7 culture for a sowing experiment with six media. S7 extract was added to OMA and Murashige and Skoog media for seed culture . Without S7, seeds sprouted on three media; the highest sowing bud ratio (SBR) was 1.96%±1.26%. In addition, seedlings emerged on one media; the highest percentage of seedling emergence (PSE) was 0.96%±1.07%. With S7, seeds sprouted and formed seedlings on all six media. Seeds germinated best on peat soil:sawdust (1:1) medium, with the SBR and PSE reaching 26.68%±6.26% and 20.97%±6.93%, respectively. These results showed that S7 can promote seed germination of D. officinale and can be applied to field sowing and that the culture medium influences the effects of S7. After adding high-concentration S7 mycelium extract to OMA medium, the protocorm formed after 50 days of culture, 20 days earlier than the control group; leaves formed on day 60; and the control group protocorm did not continue to develop. After 80 days of culture, the seed germination rate was 54.90%±2.46%, 57.6% higher compared to the control group ( P

Effect of different media, temperature, pH on the growth of Macrophomina phaseolina (Tassi) Goid causing root rot of sesame

Among fungal diseases, stem root rot or charcoal rot caused by Macrophomina phaseolina (Tassi) Goid iswidely distributed and highly destructive disease of sesame. Different synthetic media were tested to select suitable media for the growth of M. phaseolina. Among them, oat meal agar, malt dextrose, Elad and Chet medium showed significantly high mycelial growth at 120 hrs. The maximum growth of M. phaseolina was observed at 30, 35 and 40°C which indicates preference towards higher temperatures and also maximum growth recorded at 5 and 7 pH. Extracts of safflower, mustard, sunflower, groundnut, soybean and sesame amended in media have shown more mycelial growth of M. phaseolina while castor stem extract recorded lowest growth.

In vitro culture and greenhouse acclimatization of Oncidium varicosum (Orchidaceae) with microorganisms isolated from its roots

Abstract Sustainable production of orchids may be achieved with the use of symbiotic microorganisms that improve resistance of plants to pests and diseases and reduce the need of substrate fertilization. In this study, one fungus (F1), one yeast (Y1) and one gram-positive bacteria (B+) were isolated from the roots of the orchid Oncidium varicosum and used in the cultivation of protocorms and plantlets obtained from seeds of this species. Cultivation of protocorms in Murashige and Skoog (MS) medium enriched with sucrose and inoculated with microorganisms did not result in better development of protocorms. However, the use of plantlets in the rooting phase in MS medium without sucrose and inoculated with B+ resulted in plantlets with more leaves and roots and longer shoots and roots, suggesting synergism between microorganism and plant when sucrose is absent. The major benefits of co-cultivating plantlets and these microorganisms were observed in the acclimatization in the greenhouse. Plantlets obtained with oat meal agar medium and B+ showed the highest pseudobulb diameter, number of roots, height and fresh weight among treatments. We concluded that the application of rooting-derived microorganisms in the in vitro culture and plantlet acclimatization of Oncidium varicosum is beneficial.

The MAP Kinase CfPMK1 Is a Key Regulator of Pathogenesis, Development, and Stress Tolerance of Colletotrichum fructicola.

The Ascomycetes fungus Colletotrichum fructicola causes severe diseases on a wide range of crops, fruits, and vegetables. Its pathogenic mechanisms, however, remain poorly understood. Mitogen-activated protein kinases (MAPKs) are conserved regulators of fungal development and pathogenesis. In this study, a Fus3/Kss1-related MAPK from C. fructicola was functionally characterized via gene deletion. On potato dextrose agar (PDA) and oatmeal agar media, the CfPMK1 gene deletion mutants (ΔCfPMK1) were slightly reduced in radial growth rate, severely limited in aerial hyphal differentiation and hyphal melanization, and formed deformed perithecia that were smaller in size and more compactly organized relative to wild type. When artificially inoculated on plants, conidia of these mutants failed to differentiate appressoria or penetrate cuticle, and their pathogenicity defect could not be rescued by wounding plant tissue prior to inoculation. On PDA, ΔCfPMK1 mutants were hypersensitive to osmotic stresses, but were more tolerant to membrane and cell wall stresses. Genetic complementation rescued all phenotypic changes associated with CfPMK1 gene deletion. Based on GFP fusion expression, CfPMK1 protein accumulation was detected at all life stages, and the accumulation level was higher in nascent appressoria relative to conidia. Overall, this study identified CfPMK1 as a key regulator of appressorium and sexual development, pathogenesis, and stress tolerance in C. fructicola.

Morphological, Pathological and Cultural Characteristics of Magnaporthe Oryzae Triticum Causing Blast of Wheat and its Fungicidal Control

Magnaporthe oryzae Triticum causing blast a devastating disease of wheat. An attempt was taken to study the morphological, pathological and cultural characteristics of M. oryzae Triticum and its in-vitro fungicidal control. Four isolates were isolated from infected wheat inflorescence. Conidia of the isolates were solitary, pyriform to obclavate, pale brown, smooth, granular to guttulate, 2-septate; hilum truncate, protruding and not darkened. Isolates were positive in pathogenicity test on wheat and caused characteristic eye shape lesions on leaves. The wheat blast isolates did not produce any blast symptom in rice. M. oryzae Triticum showed consistently better mycelial growth at pH 5.5, 29°C and in Oat Meal Agar medium. Efficacy of six fungicides such as Autostin 50WGD, Nativo 75WG, Diathane M 45, Khowin 50WP, Ridomil Gold MZ 68WG and Provax 200WP at concentrations of 50 ppm, 100 ppm and 150 ppm was evaluated against M. oryzae Triticumin in-vitro. Autostin 50WGD, Nativo 75WG and Knowin 50WP inhibited the growth of M. oryzae Triticum completely at all three concentrations. Therefore, these three fungicides may be suggested to control blast disease of wheat.

Seed germination and development of orchid seedlings (Cyrtopodium saintlegerianum) with fungi

Abstract Fungi of Rhizoctonia complex are mycorrhizal of orchids and may to germinate yours seeds and development the seedlings. In this context, our objective was to select a fungal isolate to promote seed germination and seedling development of Cyrtopodium saintlegerianum. Pelotons were found in the roots and three mycorrhizal fungi were isolated. We tested mycorrhizal isolates obtained from C. saintlegerianum roots and six mycorrhizal fungi from other orchids as well three pathogenic isolates (of rice and bean) to germinate the seeds in oatmeal-agar medium. Seeds not inoculated were used as control. The isolates En07 (Waitea circinata), Cs10 (Tulasnella sp.) and Ro88 (Rhizoctonia oryzae) were efficient to promote seed germination, but only En07 differing statistically of the control. The non-specific isolate En07 promoted germination in 81% of seeds and the specific isolate (Cs10) promoted 60%, evidencing the non-specificity mycorrhizal association in this orchid during germination. Axenic seedlings were inoculated with four mycorrhizal fungi (non-inoculated seedlings - control). After six months, the isolates En07 and Cs10 were efficient in the interaction with the seedlings, but did not differ to the control. Therefore, our results suggested that fungi of the Rhizoctonia complex can be used in the germination and seedling development of C. saintlegerianum.

Cultural and morphological studies on Ponnampet leaf and neck blast isolates of Magnaporthe grisea (Herbert) barr on rice (Oryza sativa L.)

The study was carried out to standardize the optimal growth, sporulation and production of perfect stage of pathogen on different media. Among different media used such as Potato dextrose Agar (PDA), Oat meal Agar, Ragi flour agar, yeast extract + 2% soluble starch, Host extract + 2% soluble sucrose agar, Potato dextrose agar + Biotin + Thiamine and Rice flour agar, Oat meal agar and potato dextrose agar was found to be best media for radial growth and sporulation of M. grisea. Maximum conidia length (9.46?m) and breadth (7.36?m) was recorded in Oat meal agar followed by Potato dextrose agar and least conidia length (6.15 ?m) and breadth (5.11 ?m) was recorded in ragi flour media after 20 days of inoculation. Conidial size varied in leaf and neck blast isolates, the maximum mean colony diameter of 88.00mm and 89.16mm in neck and leaf blast was recorded in Oat meal agar respectively. The maximum sporulation mean index was observed in Oat Meal agar of 3.15 ?m in leaf and 3.20 ?m in neck blast was recorded. The best growth of the pathogen was recorded at optimum pH range from 6.0 - 7.0 and temperature of 27oC. Therefore oat meal agar media was found to be best among all the media used for growth, sporulation, conidial size and colony characters of M. grisea.

Highly compatible Epa-01 strain promotes seed germination and protocorm development of Papilionanthe teres (Orchidaceae)

Symbiotic seed germination serves as a preferred method for orchid multiplication related to conservation and reintroduction programs, which involves isolation, identification, and germination-enhancing testing of symbiotic fungi. This study uses seeds of Papilionanthe teres, a locally endangered and medicinally valuable epiphytic orchid, to attract germination-enhancing fungi on its four host plants. Only one common and highly compatible fungus (Epa-01 strain, Epulorhiza sp.), isolated from seed baiting near three host plants (Averrhoa carambola, Lagerstroemia villosa, Callistemon rigidus), enhanced seed germination by more than 80 % and promoted protocorm development to reach stage 5 (with two leaves). Seeds cocultured with the Epa-01 strain and oat meal agar medium significantly outperformed in germination and growth speed compared with those cocultured with asymbiotic germination medium only, indicating that symbiotic seed germination is an effective method for P. teres seedling production. Bark substrate types have profound effects on symbiotic seed germination and protocorm development possibly due to different abundance and growth vitality of the Epa-01 strain on the four host plants. A significant difference was found in the developmental speed of symbiotic seeds between A. carambola and the other three host plants under ex situ and ex vitro seed germination treatments (all P < 0.05). The results suggest that in situ seed baiting may be used to effectively capture germination-enhancing fungi in epiphytic orchids, and testing the effects of bark substrate types on seed germination and protocorm development contributes to selecting appropriate host plants for its reintroduction into natural habitats.

Self- and nonself recognition during hyphal interactions in Rosellinia necatrix

Hyphal interactions of 10 Rosellinia necatrix isolates were analyzed. Most incompatible pairings produced broad melanized barrage lines, with a few exceptions. The variation in barrage lines revealed using light microscopy might result from distinct frequencies of different hyphal interaction types. In incompatible pairings, hyphal anastomosis was rarely observed. Activated-charcoal treatment of oatmeal agar media prevented both incompatible and compatible reactions. FUN-1 staining showed vacuole dysfunction at hyphal interaction sites, and the localization of a Lifeact-GFP mutant revealed that actin dynamics was prominent in compatible pairings. These results suggested that self/nonself recognition commonly proceeded to vacuole dysfunction and that actin dynamics played a critical role in the restoration of vacuole integrity.

Toxicity of copper hydroxide, dithianon, fluazinam, tebuconazole and pyraclostrobin to Didymella applanata isolates from Serbia

A study of the in vitro sensitivity of 10 isolates of Didymella applanata to copper hydroxide, dithianon, fluazinam, tebuconazole and pyraclostrobin, was conducted. The isolates were derived from diseased raspberry canes sampled during 2013 at five localities in western part of Serbia, known as the main raspberry growing region of the country. Prior to sensitivity testing experimental conditions for radial growth assay were optimized. The results showed that the temperature of 22°C, oatmeal agar medium and 12/12 hrs light/ darkness light regimen provided the best conditions for sensitivity tests. Most of D. applanata isolates were sensitive to the tested fungicides. The narrowest range of EC50 values was recorded for tebuconazole (1.42–2.66 mg L−1). The widest range of EC50 values was obtained for pyraclostrobin, ranging from 0.17 mg L−1 to 55.33 mg L−1. The EC50 values for the studied isolates were 39.48–51.19 mg L−1 for copper hydroxide, 12.12–18.73 mg L−1 for dithianon and 5.72–42.56 mg L−1 for fluazinam. According to resistance factor values, all D. applanata isolates were sensitive to copper hydroxide, dithianon and tebuconazole. Among tested isolates, six were highly resistant to pyraclostrobin (RFs in the range of 207.1–325.5) and two moderately resistant to fluazinam (RFs were 3 and 7.4), respectively.

Evaluation of Culture Media for Growth Characteristics of Alternaria solani, Causing Early Blight of Tomato

Early blight is most common and devastating disease in tomato plant caused by deuteromycotina fungi, Alternaria solani. This fungus grows well in potato dextrose agar and Richard’s broth medium in vitro. The growth of the fungi were tested under culture in twelve different liquid and solid media and compared with each other. Potato dextrose agar and oat meal agar among solid media and Richard’s broth and Sabouraud’s broth among liquid media appeared to be better than other media for growth of tomato early blight causing fungi. The growth characteristics such as color of colony and substrate, margin of colony, topography of mycelium along with the sporulation of the test fungus were studied on these solid media. Fungus sporulation was best in oat meal agar media. Maximum growth of the fungus was observed at 8 days after inoculation with continuous increasing growth in the potato dextrose broth (PDB) medium, although growth rate was decreasing after the 2 days of inoculation. This study will be helpful for further investigations on the physiology of the fungus and management of the disease. This investigation may be useful for taxonomic study of the fungus.

A modified medium for improved sporulation of gray mold pathogen, Botryotinia ricini (Godfrey) Whetzel in castor (Ricinus communis L.)

Oat meal agar medium enriched with gallic acid, L-asparagine and castor pericarp extract was developed to enhance sporulation of castor gray mold pathogen, Botryotinia ricini. The enriched oat meal agar medium supported higher sporulation compared to oat meal agar medium and corn meal agar medium which are commonly used for growing B. ricini.

First report of Helminthosporium spiciferum (Bainer) Nicot on mint (Mentha arvensis)

Leaf blight of mint (Mentha arvensis) is a new disease caused by Helminthosporium spiciferum on mentha leaves in India. Blight symptoms were observed on mentha leaves in the month of April, 2011. The fungal pathogen causing the disease was isolated on oatmeal agar medium and the pathogenicity was confirmed on leaves of mentha plant and Koch Postulates were established. This is the first report of the occurrence of leaf blight of mentha in India.

Symbiotic propagation of seedlings of Cyrtopodium glutiniferum Raddi (Orchidaceae)

In nature, orchid seeds obtain the nutrients necessary for germination by degrading intracellular fungal structures formed after colonization of the embryo by mycorrhizal fungi. Protocols for asymbiotic germination of orchid seeds typically use media with high concentrations of soluble carbohydrate and minerals. However, when reintroduced into the field, seedlings obtained via asymbiotic germination have lower survival rates than do seedlings obtained via symbiotic germination. Tree fern fiber, the ideal substrate for orchid seedling acclimatization, is increasingly scarce. Here, we evaluated seed germination and protocorm development of Cyrtopodium glutiniferum Raddi cultivated in asymbiotic media (Knudson C and Murashige & Skoog) and in oatmeal agar (OA) medium inoculated with the mycorrhizal fungus Epulorhiza sp., using non-inoculated OA medium as a control. We also evaluated the performance of tree fern fiber, pine bark, eucalyptus bark, corncob and sawdust as substrates for the acclimatization of symbiotically propagated plants. We determined germination percentages, protocorm development and growth indices at 35 and 70 days of cultivation. Relative growth rates and the effects of substrates on mycorrhizal formation were calculated after 165 days of cultivation. Germination efficiency and growth indices were best when inoculated OA medium was used. Corncob and pine bark showed the highest percentages of colonized system roots. The OA medium inoculated with Epulorhiza sp. shows potential for C. glutiniferum seedling production. Corncob and pine bark are promising substitutes for tree fern fiber as substrates for the acclimatization of orchid seedlings.

Compatible fungi, suitable medium, and appropriate developmental stage essential for stable association of Dendrobium chrysanthum

Establishment of symbiotic association at the appropriate developmental stage helped maintain continued growth which is vital for the long-term ex vitro survival of the orchid. In the present study, symbiotic association was carried out using different developmental stages of Dendrobium chrysanthum and pathogenic Rhizoctonia isolates (obtained from orchids and non-orchid hosts) in different culture media. Isolate 2162 supported highest symbiotic germination on OMA-S (oat meal agar medium without nutrients + sucrose), whereas, stable symbiotic association with plantlets was obtained with isolate 4634 on OMA-NC (oat meal agar medium + cellulose). Isolate Dc-2S2 obtained from the host plant did not promote seed germination nor did it form association with protocorms or plantlets. This study, for the first time identifies a combination of compatible fungal isolate, suitable culture medium, and appropriate developmental stage at which symbiotic association in vitro can be deemed successful for the medicinally important orchid, D. chrysanthum.