The fungus that causes Ramularia leaf spot in barley is the latest organism to have its genome sequenced and investigated

  • 10
  • AUG
  • 2016

The fungus Ramularia collo-cygni can live between the cells inside of barley plants without causing symptoms for many weeks. However, when conditions change inside the plant, the fungus becomes aggressive. It secretes plant toxins that produce brown, rectangular lesions within a yellow ring, which are visible on both sides of the leaves. The leaves die prematurely, reducing photosynthesis, and causing yield losses of up to 70 percent. How the fungus makes these toxins, and the role the toxins play in colonising the plants, remain largely unknown, but the new study has identified a large number of genes involved in secreting potentially toxic chemicals and proteins. The recent emergence of the disease as a major problem for barley-growers may be due to recent genetic changes to the fungus or to barley plants, or mary result from other changes to farming practice.

UK farmers produce about 7.3 million tonnes of barley each year, worth around £1 billion. Roughly a quarter of the barley is used to produce beers, whiskeys and other drinks, and the remainder is predominantly used as animal feed.

Professor Kim Hammond-Kosack, a senior scientist at Rothamsted Research and one of the study’s authors, said:

“It is probable that this fungus produces a complex arsenal of toxins to help it to colonise barley plants. By studying the expression of genes at different stages of the life of the fungus and in various environmental scenarios, we may be able to discover toxins that we don’t yet know about, and find out more about the mechanisms that regulate the formation of disease symptoms.”

The genome also supports current ideas about how the fungus evolved. The scientists confirmed the classification of the fungus within the same group as other plant pathogens, and as a close relative of Zymoseptoria tritici, the cause of Septoria tritici (leaf) blotch in wheat. They found common genes thought to play a role in concealing the fungus from the plant’s immune system.

Dr Jason Rudd, a senior scientist at Rothamsted Research and another of the study’s authors added:

“Barley is the UK’s second most common crop after wheat, so Ramularia leaf spot has big consequences for farmers here as well as in other important barley growing regions across Europe and South America. The large overall similarity in the genome sequences between Ramularia and Zymoseptoria suggests they may both be open to a common future disease-prevention strategy. The bits which differ will most probably explain why they are particular for barley and wheat crops, respectively. We hope our data will provide the foundation for scientists to try new approaches to treating these diseases.”

About Edinburgh Genomics

Edinburgh Genomics is one of Europe's largest academic genomics facilities, based in the School of Biological Sciences, the University of Edinburgh. Edinburgh Genomics works with academic and commercial partners to deliver world class data and analyses using Illumina and other next generation sequencing platforms. Edinburgh Genomics has core funding from the university of Edinburgh, the Natural Environment Research Council (NERC) and BBSRC. For more information, see 

About Rothamsted Research
Rothamsted Research is the longest-running agricultural research institute in the world. We work from gene to field with a proud history of ground-breaking discoveries, from crop treatment to crop protection, from statistical interpretation to soils management. Our founders, in 1843, were the pioneers of modern agriculture, and we are known for our imaginative science and our collaborative influence on fresh thinking and farming practices.
Through independent science and innovation, we make significant contributions to improving agri-food systems in the UK and internationally. In terms of the institute’s economic contribution, the cumulative impact of our work in the UK was calculated to exceed £3000 million a year in 20151. Our strength lies in our systems approach, which combines science and strategic research, interdisciplinary teams and partnerships.
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About LAT
The Lawes Agricultural Trust, established in 1889 by Sir John Bennet Lawes, supports Rothamsted Research’s national and international agricultural science through the provision of land, facilities and funding. LAT, a charitable trust, owns the estates at Harpenden and Broom's Barn, including many of the buildings used by Rothamsted Research. LAT provides an annual research grant to the Director, accommodation for nearly 200 people, and support for fellowships for young scientists from developing countries. LAT also makes capital grants to help modernise facilities at Rothamsted, or invests in new buildings.