Difference between revisions of "Team:Bordeaux/Problem"
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<h6 align= "justify"> Favorable conditions in Aquitaine </h6> | <h6 align= "justify"> Favorable conditions in Aquitaine </h6> | ||
− | <p align="justify" style="text-indent: 3vw;"> Downy mildew requires a <b> warm, moist, and humid environment </b> to reproduce and infect the plant, <b> which is the case in the Aquitaine region </b>. Generally, a correlation exists between low rainfall during the winter-spring period and slight epidemics. Mature oospores germinate best if their outer walls are ruptured, possibly as a result of a light freeze and sufficient humidity. The germination of oospores requires soil temperatures of 12 to 13°C and moisture. Common infection symptoms include necrosis of the stem or shoot, discoloration, brown spotting and yellowish-green tips of the leaves and mycelium invasion of the grapes (Figure 1). [1] These symptoms gravely affect the plant's photosynthetic ability and it's grape production. Thus, Downy mildew has been <b> considered the most devastating disease </b> caused by a <b> filamentous pathogen </b> to affect European vineyards and this has lead them to search for effective measures to protect their vines. Unfortunately, most of these | + | <p align="justify" style="text-indent: 3vw;"> Downy mildew requires a <b> warm, moist, and humid environment </b> to reproduce and infect the plant, <b> which is the case in the Aquitaine region </b>. Generally, a correlation exists between low rainfall during the winter-spring period and slight epidemics. Mature oospores germinate best if their outer walls are ruptured, possibly as a result of a light freeze and sufficient humidity. The germination of oospores requires soil temperatures of 12 to 13°C and moisture. Common infection symptoms include necrosis of the stem or shoot, discoloration, brown spotting and yellowish-green tips of the leaves and mycelium invasion of the grapes (Figure 1). [1] These symptoms gravely affect the plant's photosynthetic ability and it's grape production. Thus, Downy mildew has been <b> considered the most devastating disease </b> caused by a <b> filamentous pathogen </b> to affect European vineyards and this has lead them to search for effective measures to protect their vines. Unfortunately, most of these measures use copper sulfate which pollutes the surrounding soils. </p> |
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<h6 align="justify"> Infection Mode of Downy Mildew </h6> | <h6 align="justify"> Infection Mode of Downy Mildew </h6> | ||
− | <p align="justify" style="text-indent: 3vw;"> In winter, <i> Plasmopara viticola </i> is present on dead leaves on the ground as oospores. They are inactive and do not produce any symptoms. When rain falls during spring, these eggs grow and release zoospores when the temperature exceeds 11 degrees. The zoospores will be able to spread and infect the plant | + | <p align="justify" style="text-indent: 3vw;"> In winter, <i> Plasmopara viticola </i> is present on dead leaves on the ground as oospores. They are inactive and do not produce any symptoms. When rain falls during spring, these eggs grow and release zoospores when the temperature exceeds 11 degrees. The zoospores will be able to spread and infect the plant upper tissues through rainwater splashes. [5] </p> |
− | <p align="justify" style="text-indent: 3vw;">The <b> primary contamination </b> begins by the emission of a filament through the stomatal area where the parasite begins to <b> develop sinkers </b> from which is formed the mycelial network. These sinkers <b> help to feed <i>Plasmopara viticola </i> by stealing the plant | + | <p align="justify" style="text-indent: 3vw;">The <b> primary contamination </b> begins by the emission of a filament through the stomatal area where the parasite begins to <b> develop sinkers </b> from which is formed the mycelial network. These sinkers <b> help to feed <i>Plasmopara viticola </i> by stealing the plant nutrients, </b> which creates discolored and yellowish areas on the leaves called “oil stains”. After, on leaves bottom, conidiophores and conidia are formed. These symptoms cause damages to the leave tissues and affect the plant photosynthetic ability, which slows down the maturity of the plant.</p> |
<p align="justify" style="text-indent: 3vw;">During the <b> secondary contamination </b>, the conidia are transformed into zoospores that <b>contaminate the surrounding tissues</b>, weakening the plant even more and creating <b> unreparable lesions </b>. </p> | <p align="justify" style="text-indent: 3vw;">During the <b> secondary contamination </b>, the conidia are transformed into zoospores that <b>contaminate the surrounding tissues</b>, weakening the plant even more and creating <b> unreparable lesions </b>. </p> | ||
<p class="reference" align="left"> <b>Literature Cited: </b> </p> | <p class="reference" align="left"> <b>Literature Cited: </b> </p> | ||
− | <p class="reference" align="left"> [5] | + | <p class="reference" align="left"> [5] Biologie du mildiou de la vigne. Cycle du Mildiou de la vigne. <a href="http://www.agro.basf.fr/agroportal/fr/fr/cultures/la_vigne/les_maladies4/biologie_mildiou_vigne.html" target="_blank">BASF</a></p> |
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<h6 align="justify"> Common Solutions </h6> | <h6 align="justify"> Common Solutions </h6> | ||
− | <p align="justify" style="text-indent: 3vw;"> Since <b> repairing damaged tissues </b> infected by downy mildew <b>is impossible</b>, the majority of the solutions available to | + | <p align="justify" style="text-indent: 3vw;"> Since <b> repairing damaged tissues </b> infected by downy mildew <b>is impossible</b>, the majority of the solutions available to vineyards are preventive solutions, mainly through <b>preventing primary infections</b>. This is done by spraying fungicides on the organs that are most infected: leaves and stems. The <b>most efficient preventive treatment</b> was discovered at the end of the 19th century: a solution made of copper sulfate also known as <b>"Bouillie Bordelaise"</b>, the only treatment used until the end of the 20th century. </p> |
<p align="justify" style="text-indent: 3vw;"> Recently, more <b> models </b> and devices designed to be used by individual growers measure temperature, humidity and leaf wetness and provide <b>treatment recommendations based on algorithms</b> similar to the Goidànich model. This general algorithm defined as the 3–10 spray strategy, is prescribed when the average temperature is above 10°C, more than 10 mm of rain have fallen within 24 h and shoot length in the vineyard is at least 10 cm. Despite evident imprecision due to the strict parameters, <b>this general model can reliably predict the first risk period</b> and recommend thereafter a <b>treatment schedule</b> that will allow growers to prevent development of severe downy mildew in vineyards. </p> | <p align="justify" style="text-indent: 3vw;"> Recently, more <b> models </b> and devices designed to be used by individual growers measure temperature, humidity and leaf wetness and provide <b>treatment recommendations based on algorithms</b> similar to the Goidànich model. This general algorithm defined as the 3–10 spray strategy, is prescribed when the average temperature is above 10°C, more than 10 mm of rain have fallen within 24 h and shoot length in the vineyard is at least 10 cm. Despite evident imprecision due to the strict parameters, <b>this general model can reliably predict the first risk period</b> and recommend thereafter a <b>treatment schedule</b> that will allow growers to prevent development of severe downy mildew in vineyards. </p> | ||
− | <p align="justify" style="text-indent: 3vw;"> The weakness of this type of model is that </b>the number of recommended pesticide sprays is usually greater than what is needed to avoid an epidemic</b>, particularly at the beginning of the season. In 2006, Swiss researchers applied a concept based on a tolerance threshold for Downy mildew under the particular climatic conditions of southern Switzerland and were able to eliminate half of the recommended treatments. (Jermini et al., 2006). This paradigm change, from a focus on the pathogen and the disease toward a threshold concept, requires detailed knowledge of the host and its relationship with the environment and human activities but opens the path for a new era of pesticide applications. However, these are <b>highly complex interactions</b> and there is <b>little available data</b> describing them. The information that is available is <b>heavily biased</b> by site, year and cultivar factors, and so cannot be readily used for simulation and modeling activities. [1] More | + | <p align="justify" style="text-indent: 3vw;"> The weakness of this type of model is that </b>the number of recommended pesticide sprays is usually greater than what is needed to avoid an epidemic</b>, particularly at the beginning of the season. In 2006, Swiss researchers applied a concept based on a tolerance threshold for Downy mildew under the particular climatic conditions of southern Switzerland and were able to eliminate half of the recommended treatments. (Jermini et al., 2006). This paradigm change, from a focus on the pathogen and the disease toward a threshold concept, requires detailed knowledge of the host and its relationship with the environment and human activities but opens the path for a new era of pesticide applications. However, these are <b>highly complex interactions</b> and there is <b>little available data</b> describing them. The information that is available is <b>heavily biased</b> by site, year and cultivar factors, and so cannot be readily used for simulation and modeling activities. [1] More similar studies could help reduce the use of pesticides in the region. </p> |
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− | <!-- ---------------------------------------- PLANT | + | <!-- ---------------------------------------- PLANT NATURAL DEFENSES ---------------------------------------------------------- --> |
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− | <h6 align="justify"> | + | <h6 align="justify"> Plant natural defenses </h6> |
− | <p align="justify" style="text-indent: 3vw;"> Plant | + | <p align="justify" style="text-indent: 3vw;"> Plant immunization is based on the same principle as human immunization: activating its natural defenses before contamination by an infectious agent. The concept is simple; putting the plant in contact with a molecule able to activate it's natural defenses: <b> an elicitor </b> . In nature, there are many elicitors produced by micro-organisms (exogenous elicitors) or by the plant itself when it is attacked (endogenous elicitors). The presence of an elicitor in the plant triggers a series of cellular reactions including the <b> production of molecules to strengthen the resistance of cell walls </b>, but also the <b> production of plant antibiotics </b> such as <b>phytoalexins</b> or <b>defense proteins</b>. These compounds have antifungal and antibacterial properties. The external application of a natural elicitor or a similar synthetic molecule thus results in the production of phytoalexins or defense proteins in the absence of any pathogen. The "immunized" plant is ready to fight back if attacked. </p> |
<p align="justify" style="text-indent: 3vw;"> First, the cell wall forms a physical barrier which prevents the penetration of most microbes. Then, if some pathogens are able to cross this wall, the infection depends on the ability of the plant to perceive and to trigger defense reactions that would prevent the development of the disease. This recognition is done with certain compounds, known as elicitors from the pathogen or plant. <b> The fixing of an elicitor to a plant cell receptor initiates a cascade of events that leads to the synthesis of defense compounds </b>. The best known are antimicrobial compounds such as <b> phytoalexins </b> and <b> Pathogenesis Related proteins </b>. </p> | <p align="justify" style="text-indent: 3vw;"> First, the cell wall forms a physical barrier which prevents the penetration of most microbes. Then, if some pathogens are able to cross this wall, the infection depends on the ability of the plant to perceive and to trigger defense reactions that would prevent the development of the disease. This recognition is done with certain compounds, known as elicitors from the pathogen or plant. <b> The fixing of an elicitor to a plant cell receptor initiates a cascade of events that leads to the synthesis of defense compounds </b>. The best known are antimicrobial compounds such as <b> phytoalexins </b> and <b> Pathogenesis Related proteins </b>. </p> | ||
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<p class="reference" align="left"> <b>Literature Cited: </p> | <p class="reference" align="left"> <b>Literature Cited: </p> | ||
− | <p class="reference" align="left"> [7] | + | <p class="reference" align="left"> [7] Les Stimulateurs naturels de défense (SDN) de la Vigne <i> Chambre d'agriculture Indre et Loire </i></p> |
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<h6> <a href= "https://2015.igem.org/Team:Bordeaux" style=" color: #FF5E00;"> Home ☚ </a> Previous Page . Next Page <a href= "https://2015.igem.org/Team:Bordeaux/Description" style=" color: #FF5E00;"> ☛ Description </h6> | <h6> <a href= "https://2015.igem.org/Team:Bordeaux" style=" color: #FF5E00;"> Home ☚ </a> Previous Page . Next Page <a href= "https://2015.igem.org/Team:Bordeaux/Description" style=" color: #FF5E00;"> ☛ Description </h6> | ||
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Latest revision as of 02:03, 19 September 2015