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Matthew E. Smith - One of the best experts on this subject based on the ideXlab platform.
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isolation source matters Sclerotia and ectomycorrhizal roots provide different views of genetic diversity in cenococcum geophilum
Mycologia, 2018Co-Authors: Keisuke Obase, Yosuke Matsuda, Greg W. Douhan, Matthew E. SmithAbstract:ABSTRACTCenococcum geophilum forms Sclerotia and ectomycorrhizas with host plants in forest soils. We demonstrated the differences in genetic diversity of C. geophilum between cultured isolates from Sclerotia and those from ectomycorrhizal roots in the same 73 soil samples based on glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene sequences and newly developed microsatellite markers. Based on GAPDH sequences, 759 cultured isolates (553 from Sclerotia and 206 from ectomycorrhizas) were classified into 107 “genotypes” with sequence variation of up to 8.6%. The total number of GAPDH genotypes per soil sample ranged from 1 to 9, but genotypes that were shared between Sclerotia and ectomycorrhizas were uncommon (0–3 per soil sample). More than 50% of GAPDH genotypes were unique to one source in most soil samples. Unique GAPDH genotypes were detected from either scleotia or ectomycorrhizal roots in most of the soil samples. Multilocus analysis using nine microsatellite markers provided additional resolution...
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Culturable fungal assemblages growing within Cenococcum Sclerotia in forest soils.
FEMS microbiology ecology, 2014Co-Authors: Keisuke Obase, Yosuke Matsuda, Greg W. Douhan, Matthew E. SmithAbstract:The ectomycorrhizal fungus Cenococcum geophilum (Ascomycota, Dothideomycetes) forms black, round to irregular Sclerotia in forest soils. Fungi that colonize the Sclerotia appear to affect Sclerotia viability and may play an important role in the life history of Cenococcum. Some of the fungi could also affect nutrient cycling by decomposing Cenococcum Sclerotia, which are melanized and recalcitrant to decay. We used a culture-based method to document the fungal communities growing inside surface-sterilized Sclerotia that were collected from forest soils. Cenococcum was successfully isolated from 297 of 971 Sclerotia whereas 427 Sclerotia hosted fungi other than Cenococcum. DNA barcoding of the internal transcribed spacer rDNA followed by grouping at 97% sequence similarity yielded 85 operational taxonomic units (OTUs) that consisted primarily of Ascomycota (e.g. Chaetothyriales, Eurotiales, Helotiales, Pleosporales) and a few Basidiomycota and Mucoromycotina. Although most fungal OTUs were infrequently cultured, several OTUs such as members of Asterostroma, Cladophialophora, Oidiodendron, and Pleosporales were common and found across many sites. Our results suggest that Cenococcum Sclerotia act as a substrate for diverse fungi. The occurrence of several OTUs in Sclerotia across many sites suggests that these fungi may be active parasites of Cenococcum Sclerotia or may preferentially use Sclerotia as a nutrient source.
C R Wilson - One of the best experts on this subject based on the ideXlab platform.
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effect of inoculum density of sclerotium cepivorum on the ability of trichoderma koningii to suppress white rot of onion
Plant Disease, 2004Co-Authors: D A Metcalf, J.j.c. Dennis, C R WilsonAbstract:ABSTRACT Amendment of soil with Trichoderma koningii strain Tr5 grown on autoclaved white millet grain provided between 63 and 79% control of white rot of onion when added to soil containing 10, 25, 50, or 100 Sclerotia of Sclerotium cepivorum per kilogram of soil at the time of onion seed sowing. There was no significant difference in the proportion of S. cepivorum infections suppressed among the different Sclerotial density treatments. Rhizosphere colonization by T. koningii Tr5 was assessed by incubating onion roots sampled from plants growing in soil with the appropriate density of Sclerotia, on a Trichoderma selective medium (Rose bengall-Allisan-streptomycin-Previcur agar) developed for the purpose of the study. Trichoderma spp. isolated were typed by comparison of culture morphology as well as polygalacturonase (PG) (EC 3.2.1.15) and pectinesterase (PE) (EC 3.1.1.11) isozyme profiles to the series of one PG and two PE isozymes known to be produced by T. koningii Tr5. The method was used successfull...
Naglaa Hassan - One of the best experts on this subject based on the ideXlab platform.
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carbon loss by Sclerotia of sclerotium rolfsii under the influence of soil ph temperature and matric potential and its effect on Sclerotial germination and virulence
Applied Soil Ecology, 2014Co-Authors: Mitsuro Hyakumachi, S N Mondal, Mohsen Mohamed Elsharkawy, Naglaa HassanAbstract:Abstract Germinability and virulence of Sclerotia of Sclerotium rolfsii were assessed after 50 days of exposure of 14 C-labeled Sclerotia to soil at 0, −5 and −15 kPa and pH 6.9, or to soil at 15, 25 or 30 °C, pH 5 or 8 and −1 kPa. Evolution of 14 CO 2 accounted for the greatest share of endogenous carbon loss from Sclerotia under all soil conditions, except in water-saturated soil (0 kPa), in which Sclerotial exudates contributed the major share of carbon loss. Total evolution of 14 CO 2 from Sclerotia in soil at −15 kPa (42.4% of total 14 C) and at −5 kPa (38%) was significantly higher than at 0 kPa (23.8%). Evolution of 14 CO 2 in soil at 25 or 30 °C was more rapid than at 15 °C with regardless of pH. Loss of endogenous carbon by Sclerotia was the greater after 50 days of exposure to soil at 0 kPa, or at 25 or 30 °C and pH 8, than at other soil conditions. Sclerotia exposed to water-saturated soil (0 kPa) showed a more rapid decline in nutrient independent germinability, viability and virulence, than to those exposed to −5 or −15 kPa. Sclerotia became dependent on nutrient for germination and lost viability and virulence within 30–40 days in soil at 25 or 30 °C, pH 8. However, more than 60% of Sclerotia retained viability in soil at 15 °C regardless of pH, even after 50 days. Radish shoot growth was increased significantly by the Sclerotia that had been exposed to soil at 0 kPa, or to soil at 25 or 30 °C and pH 8 for 50 days. In conclusion, carbon loss by Sclerotia during incubation on soil at different pH levels, temperatures and water potentials was inversely correlated with Sclerotial ability to infect radish seedlings. The relationship between carbon loss by Sclerotia and radish shoot length was positive.
K Y Rashid - One of the best experts on this subject based on the ideXlab platform.
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time and burial depth influencing the viability and bacterial colonization of Sclerotia of sclerotinia sclerotiorum
Soil Biology & Biochemistry, 2006Co-Authors: Robert W Duncan, W Dilantha G Fernando, K Y RashidAbstract:Abstract Sclerotia are the primary over wintering inoculum of Sclerotinia sclerotiorum (Lib.) de Bary. The effects of tillage on the primary inoculum are not well understood. The purpose of this research was to study Sclerotial viability over time and between burial depths in soil, to identify bacteria colonizing and degrading the Sclerotia, and determine whether these bacteria may be utilized as biological control agents. Correlation analysis indicated that a significant negative relationship existed between Sclerotial viability and elapsed temporal factors ( R 2 =−0.68, P R 2 =−0.58, P R 2 =−0.60, P S. sclerotiorum . Biodiversity of the inhibitory bacterial isolates was minimal on Sclerotia from the soil surface and within all depths sampled at three months (i.e. in January). All burial depths within the April and July sampling dates produced bacterial diversities that were distinct from each other.
Richard Smith - One of the best experts on this subject based on the ideXlab platform.
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efficacy of germination stimulants of Sclerotia of sclerotium cepivorum for management of white rot of garlic
Plant Disease, 2007Co-Authors: R M Davis, Jianjun Hao, M K Romberg, J J Nunez, Richard SmithAbstract:The ability of soil-applied garlic powder and diallyl disulfide to stimulate germination of Sclerotia of Sclerotium cepivorum, the cause of white rot of onion and garlic, was evaluated in four field trials. Because Sclerotia germinate in response to exudation of specific volatile sulfides and thiols from allium roots, sulfides applied to the ground in the absence of an allium crop cause death of the Sclerotia after they germinate and exhaust nutrient reserves. In this study, garlic powder and a synthetic garlic oil, diallyl disulfide, were incorporated into the soil in commercial fields naturally infested with S. cepivorum. Methyl bromide was included as a chemical control. Within 3 months after treatment, over 90% of the Sclerotia died in the plots treated with the germinationstimulants, which was similar to the reduction of viable Sclerotia achieved with an application of methyl bromide. The degree of Sclerotial mortality in plots treated with garlic powder at 112 kg/ha or more was almost equal to that achieved by diallyl disulfide at 0.5 ml/m2 or methyl bromide at 448 kg/ha. Despite the efficacy of the stimulants and methyl bromide to reduce populations of Sclerotia, the pathogen caused substantial root rot and yield losses in subsequent garlic crops planted about a year after soil treatment. However, germination stimulants have utility because the reduction of the vast majority of Sclerotia in a field reduces the risk of spread of the pathogen to neighboring fields.
