Abstract
Barley is one of the major cereals grown worldwide. It is used not only as a food and fodder source, but also as a major ingredient in beer and whisky production. One of the most devastating diseases of barley - powdery mildew, can cause losses up to 40 %.
Plants base their defence responses solely on innate immunity due to the lack of an adaptive immune system. Pathogens manipulate the plant immunity and hijack metabolism to favour their growth by secreting small effector proteins into the host. Barley powdery mildew fungus has a repertoire of over 500 effector proteins with conserved YxC motif in majority of them. Resistance to barley powdery mildew in the field is controlled by use of resistant varieties in a combination with fungicides.
Early disease management is crucial for effective control. Yet, the pathogen commonly develops fungicide resistance due to simple point mutations. Several studies investigated reduced fitness of plants as a cost of resistance to pathogens. In case of barley powdery mildew, most common resistance (mlo) is linked to a higher susceptibility to other pathogens and spontaneous necrosis that leads to yield reduction.
Thus, there is a clear need for alternative methods of crop protection. In the present study, I provide an overview of the current knowledge about plant pathogens and plant disease resistance. I use Arabidopsis as a model to investigate the mechanism of non-host resistance, presumed to be the most durable and broad-spectrum form of resistance. I attempt to determine how the basic resistance components contribute to resistance against powdery mildews. Furthermore, I propose an alternative strategy of achieving resistance to barley powdery mildew by application of peptide aptamers. Peptide aptamers are small proteins selected to specifically target conserved YxC motif of barley powdery mildew effectors. I present a proof-of-concept study in Arabidopsis, where overexpression of peptide aptamers significantly reduced the susceptibility to barley powdery mildew. Moreover, I set the discovery in a bigger context by summarizing genetic engineering technologies and their application in crop protection. Additionally, I attempt to investigate the structure of the barley powdery mildew effector to elucidate its function. Efforts set a foundation for engineering the plant resistance proteins to verify the recognition of pathogen effectors and execution of disease responses.
Plants base their defence responses solely on innate immunity due to the lack of an adaptive immune system. Pathogens manipulate the plant immunity and hijack metabolism to favour their growth by secreting small effector proteins into the host. Barley powdery mildew fungus has a repertoire of over 500 effector proteins with conserved YxC motif in majority of them. Resistance to barley powdery mildew in the field is controlled by use of resistant varieties in a combination with fungicides.
Early disease management is crucial for effective control. Yet, the pathogen commonly develops fungicide resistance due to simple point mutations. Several studies investigated reduced fitness of plants as a cost of resistance to pathogens. In case of barley powdery mildew, most common resistance (mlo) is linked to a higher susceptibility to other pathogens and spontaneous necrosis that leads to yield reduction.
Thus, there is a clear need for alternative methods of crop protection. In the present study, I provide an overview of the current knowledge about plant pathogens and plant disease resistance. I use Arabidopsis as a model to investigate the mechanism of non-host resistance, presumed to be the most durable and broad-spectrum form of resistance. I attempt to determine how the basic resistance components contribute to resistance against powdery mildews. Furthermore, I propose an alternative strategy of achieving resistance to barley powdery mildew by application of peptide aptamers. Peptide aptamers are small proteins selected to specifically target conserved YxC motif of barley powdery mildew effectors. I present a proof-of-concept study in Arabidopsis, where overexpression of peptide aptamers significantly reduced the susceptibility to barley powdery mildew. Moreover, I set the discovery in a bigger context by summarizing genetic engineering technologies and their application in crop protection. Additionally, I attempt to investigate the structure of the barley powdery mildew effector to elucidate its function. Efforts set a foundation for engineering the plant resistance proteins to verify the recognition of pathogen effectors and execution of disease responses.
| Originalsprog | Engelsk |
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| Forlag | Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen |
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| Status | Udgivet - 2015 |