1,721,469 research outputs found
Evaluating the survival and environmental fate of the biocontrol agent Trichoderma atroviride SC1 in vineyards in northern Italy
No full textTo study the survival in the soil and the dispersion in the environment of Trichoderma atroviride SC1 after soil applications in a vineyard. METHODS AND RESULTS: Trichoderma atroviride SC1 was introduced into soil in two consecutive years. The levels of T. atroviride populations at different spatial and temporal points following inoculation were assessed by counting the colony-forming units and by a specific quantitative real-time PCR. A high concentration of T. atroviride SC1 was still observed at the 18th week after inoculation. The vertical migration of the fungus to a soil depth of 0.4 m was already noticeable during the first week after inoculation. The fungus spread up to 4 m (horizontally) from the point of inoculation and its concentration decreased with the increasing distance (horizontal and vertical). It was able to colonize the rhizosphere and was also found on grapevine leaves. One year after soil inoculation, T. atroviride SC1 could still be recovered in the treated areas. CONCLUSIONS: Trichoderma atroviride SC1 survived and dispersed becoming an integrant part of the local microbial community under the tested conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: The persistence and rapid spread of T. atroviride SC1 represent good qualities for its future use as biocontrol agent against soilborne pathogens
Ecophysiological requirements and survival of a Trichoderma atroviride isolate with biocontrol potential
No full textTrichoderma atroviride SC1, isolated from decayed hazelnut wood in northern Italy in 2000, is a promising fungal agent for biological control of soil-borne plant pathogens. The objective of this research was to characterize the biology and ecology of this fungus, in order to determine
its environmental parameter tolerance levels and its behavior in the phylloplane and soil
systems. To better characterize T. atroviride SC1, the influences of pH, temperature, water activity and different nitrogen and carbon sources on its in vitro growth were evaluated. T. atroviride SC1 survival was assessed on strawberry leaves under controlled conditions in a greenhouse and in sterilized and non-sterilized soil samples kept at room temperature. Results
showed that isolate SC1 is mesophilic and grows best at 25 °C. The fungus tolerates a wide range of pH levels, but growth was reduced on alkaline media (pH ≥ 8). The nitrogen and carbon sources peptone, tryptone, nitrate, mannose, galactose and sucrose were associated with the highest mycelial biomass production, as compared with other potential sources of nitrogen and carbon. The fungus survived on strawberry leaves under greenhouse conditions
(25 ± 2 °C, RH = 60 ± 10%) and grew in sterilized soils at room temperature (23 ± 2 °C) for 45 d. However, no increase in mycelial dry weight was observed in non-sterilized soils. T. atroviride SC1 survived under the test conditions, showing a good potential for use in soil and foliar biocontrol application
Impact of the biocontrol agent Trichoderma atroviride Sc1 on soil microbial communities of a vineyard in Northern Italy
No full textThe fungus Trichoderma atroviride SC1 is an experimental biocontrol agent (BCA) that is active against the fungus Armillaria mellea. Following the application of Trichoderma to the surface soil of a vineyard, we used a highly specific real-time PCR, previously validated for the analysis of soil microcosms, to monitor the populations of this fungus at different soil depths over several months. The quantification obtained using this molecular method was highly correlated with laboratory assays of colony-forming units. The native communities of bacteria and fungi in the soil were analyzed using automated ribosomal intergenic spacer analysis (ARISA), and transient changes were observed following the application of T. atroviride SC1 conidia. A principal component of variance analysis demonstrated that the introduction of T. atroviride SC1 had an effect on the soil microflora during the first two weeks following inoculation. However, at later dates, environmental conditions had a higher influence on the surveyed communities than the BCA application, as confirmed through the use of the Shannon index of biodiversity. Soil depth had a strong influence on the composition and biodiversity of fungal communities. © 2009 Elsevier Ltd. All rights reserved
IOBC-WPRS Working group "Biological control of fungal and bacterial plant pathogens" Proceedings of the meeting at Graz (Austria) 7-10 June 2010
No full textReal-time PCR for detection and quantification of the biocontrol agent Trichoderma atroviride strain SC1 in soil
No full textTrichoderma (Hypocreales, Ascomycota) is a widespread genus in nature and several Trichoderma species are used in industrial processes and as biocontrol agents against crop diseases. It is very important that the persistence and spread of microorganisms released on purpose into the environment are accurately monitored. Real-time PCR methods for genus/species/strain identification of microorganisms are currently being developed to overcome the difficulties of classical microbiological and enzymatic methods for monitoring these populations. The aim of the present study was to develop and validate a specific real-time PCR-based method for detecting Trichoderma atroviride SC1 in soil. We developed a primer and TaqMan probe set constructed on base mutations in an endochitinase gene. This tool is highly specific for the detection and quantification of the SC1 strain. The limits of detection and quantification calculated from the relative standard deviation were 6000 and 20,000 haploid genome copies per gram of soil. Together with the low throughput time associated with this procedure, which allows the evaluation of many soil samples within a short time period, these results suggest that this method could be successfully used to trace the fate of T. atroviride SC1 applied as an open-field biocontrol agent. © 2008 Elsevier B.V. All rights reserved
How to develop a biofungicide based on a bacterial strain: the main steps for turning your discover into a plant protection product
No full textLess than 0.1 % of the potentially bioactive microbial biocontrol agents reaches the market (estimation based on the number of active strains reported in scientific journals, ‘grey literature’ and theses available on web and the number of registered commercial products). In the last decade research efforts on microbial biocontrol increased dramatically in EU, US and Canada, but also in India, China, Africa, Central and South America. However the EU market returns a very gloomy picture with very few commercial products available for the growers, all based on ‘old’ active ingredients (some of these strains have been identified 30 years ago or even more). The ‘new entries’ are mostly new strains of the same well-known species. To explain such situation we commonly refer to the intrinsic limiting factors in their use (i.e. microbial pesticides are expected to be less effective and more inconsistent than chemicals, they need specific environmental conditions for the application, high technical skills by growers and frequent crop monitoring, etc.) or in the economics (i.e. they are more expensive than chemicals, registration costs are too high for the companies, the market is too narrow to justify investments, etc.). However most of the product development fails for other reasons: as mistakes in the selection of the right strain (both in term of technological properties and level of efficacy) or the target disease and crop (type of disease, market size, etc.), in the IP protection and in the choice of the industrial partner to scale-up the production. This ‘how to’ presentation will define some of the most important steps in the development of a bacterial biofungicide starting from the very beginning and highlights some of the most commons mistakes that prevents these products reaching the market
Weeds influence soil bacterial and fungal communities
No full textBackground and aims
Vineyards harbour a variety of weeds, which are usually controlled since they compete with grapevines for water and nutrients. However, weed plants may host groups of fungi and bacteria exerting important functions.
Methods
We grew three different common vineyard weeds (Taraxacum officinalis, Trifolium repens and Poa trivialis) in four different soils to investigate the effects of weeds and soil type on bacterial and fungal communities colonising bulk soil, rhizosphere and root compartments. Measurements were made using the cultivation-independent technique Automated Ribosomal Intergenic Spacer Analysis (ARISA).
Results
Weeds have a substantial effect on roots but less impact on the rhizosphere and bulk soil, while soil type affects all three compartments, in particular the bulk soil community. The fungal, but not the bacterial, bulk soil community structure was affected by the plants at the late experimental stage. Root communities contained a smaller number of Operational Taxonomic Units (OTUs) and different bacterial and fungal structures compared with rhizosphere and bulk soil communities.
Conclusions
Weed effect is localised to the rhizosphere and does not extend to bulk soil in the case of bacteria, although the structure of fungal communities in the bulk soil may be influenced by some weed plant
Moderate warming in microcosm experiment does not affect microbial communities in temperate vineyard soils
No full textChanges in the soil microbial community structure can lead to dramatic changes in the soil ecosystem. Temperature, which is projected to increase with climate change, is commonly assumed to affect microbial communities, but its effects on agricultural soils are not fully understood. We collected soil samples from six vineyards characterised by a difference of about 2 A degrees C in daily soil temperature over the year and simulated in a microcosm experiment different temperature regimes over a period of 1 year: seasonal fluctuations in soil temperature based on the average daily soil temperature measured in the field; soil temperature warming (2 A degrees C above the normal seasonal temperatures); and constant temperatures normally registered in these temperate soils in winter (3 A degrees C) and in summer (20 A degrees C). Changes in the soil bacterial and fungal community structures were analysed by automated ribosomal intergenic spacer analysis (ARISA). We did not find any effect of warming on soil bacterial and fungal communities, while stable temperatures affected the fungal more than the bacterial communities, although this effect was soil dependent. The soil bacterial community exhibited soil-dependent seasonal fluctuations, while the fungal community was mainly stable. Each soil harbours different microbial communities that respond differently to seasonal temperature fluctuations; therefore, any generalization regarding the effect of climate change on soil communities should be made carefull
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