Barley is the second most important cereal crop grown in the UK – used as animal fodder, in human foods such as health foods, soups and stews, and also in the drinks production industry. High quality malting barley underpins beer and whisky production and is worth around £20Bn to the UK economy. However, barley is susceptible to a number of diseases, the most important of which is called leaf blotch and is caused by a fungal pathogen. Rothamsted Research scientists, who receive strategic funding from the BBSRC, in a collaborative work with researchers from the Universities of Hertfordshire and Nottingham and ETH Zurich, have found that that a major fungal pathogen that causes leaf blotch disease in barley crops is also present in wild grasses. The study has been published in PLOS ONE.
Professor Jon West, Rothamsted Research said: "The study was part of the PhD programme by Kevin King at Rothamsted Research and found that five very closely related species of the fungus, Rhynchosporium, are specialised to infect different wild grasses and barley, which could allow us to understand types of host resistance to diseases".
The disease is spread to new areas on infected seeds and is splashed by rain short distances within barley crops. It is possible that spores could also spread into crops from ryegrass in grass margins around fields especially when a fine spray is created by heavy rain and strong wind.
The research used molecular fingerprinting, DNA sequencing, spore morphology, scanning electron microscopy and host-infection tests and to investigate which grasses and cereals were infected by different Rhynchosporium species. The project also discovered a new species of Rhynchosporium (R. Lolii), which was found to infect only ryegrass. Novel species-specific PCR diagnostic methods were developed to distinguish the five closely related Rhynchosporium species.
Professor Bruce Fitt, Professor of Plant Pathology at the University of Hertfordshire, said: "Crops that appear to be clear of disease can suddenly develop leaf blotch symptoms unexpectedly. The source of the disease is unclear and this has puzzled farmers and researchers alike."
"However, our research shows that the fungal pathogen that causes barley leaf blotch can be found on wild ryegrasses which are common both as weeds within cereal crop fields and in the surrounding field margins."
Professor Fitt continued: "Field margins play an important role in creating areas of habitat to support wildlife and wild plants species. But the increasing demand for agricultural land to provide enough crops to feed and support the growing population is putting pressure on these little pockets of wild nature.
"And if this pathogen species can be spread from wild grasses onto barley crops and back again, further investigation is needed to identify how widespread this species is and also the role that wild grasses play as sources of disease for other crops such as wheat."