Abstract
Ramularia leaf spot is a recently emerged foliar barley disease in Europe and other parts of the globe. It is caused by the fungus Ramularia collo-cygni and characterised by chlorotic and necrotic leaf spots. The yield losses could be up 35 % of total barley production each year due to unavailability of completely resistant cultivars and the situation is currently controlled only by the use of fungicides. Importantly, in previous couple of years, the fungus has developed resistance to fungicides that have been used to control the disease indicating the risks of disease outbreaks in future. As RLS is a relatively new disease to the plant biologists, several field and laboratory studies have been performed till date to understand the pathogen infection strategies and its growth towards disease establishment. However, the host response during the infection and disease development phase remains unknown.
We utilised the proteomics technology to identify proteins in order to develop protein based molecular markers that further can be used in RLS breeding programs. Our results of sensitive and tolerant barley cultivars following infection by mild and aggressive Rcc isolates identified physiological and molecular responses of host to the pathogen. Specific proteins based on their expression pattern have been shortlisted to be used as protein markers in RLS disease diagnosis and includes candidates such as PR-1, PR-5, chorismate synthase and pheophorbide a oxygenase. These proteins are expressed particularly in Tipple after early infection and therefore could be used as protein markers in barley for RLS disease breeding.
Ramularia collo-cygni produces rubellin toxin and it is known to be a pathogenicity factor in RLS disease development. However, the amount of rubellin produced by Rcc in planta and its timing of secretion/release is presently unknown. To understand this, rubellin toxin was chemically biotinylated, and using phage display technology, an rubellin antibody was developed. Unfortunately, the rubellin antibody lacks specificity for its binding to rubellin and showed non-specific binding during our validation tests indicating it cannot be used to detect rubellin produced in fungus or in planta by microscopy.
We utilised the proteomics technology to identify proteins in order to develop protein based molecular markers that further can be used in RLS breeding programs. Our results of sensitive and tolerant barley cultivars following infection by mild and aggressive Rcc isolates identified physiological and molecular responses of host to the pathogen. Specific proteins based on their expression pattern have been shortlisted to be used as protein markers in RLS disease diagnosis and includes candidates such as PR-1, PR-5, chorismate synthase and pheophorbide a oxygenase. These proteins are expressed particularly in Tipple after early infection and therefore could be used as protein markers in barley for RLS disease breeding.
Ramularia collo-cygni produces rubellin toxin and it is known to be a pathogenicity factor in RLS disease development. However, the amount of rubellin produced by Rcc in planta and its timing of secretion/release is presently unknown. To understand this, rubellin toxin was chemically biotinylated, and using phage display technology, an rubellin antibody was developed. Unfortunately, the rubellin antibody lacks specificity for its binding to rubellin and showed non-specific binding during our validation tests indicating it cannot be used to detect rubellin produced in fungus or in planta by microscopy.
| Original language | English |
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| Publisher | Aarhus University, Faculty of Science and Technology |
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| Number of pages | 236 |
| Publication status | Published - 2019 |