The gene that provides resistance to powdery mildew in barley increases the threat of ramularia leaf spot according to new research.

The mlo gene has significantly helped reduce the threat of powdery mildew in UK barley fields however it now appears this has come at a price with ramularia becoming more prevalent, particularly in spring barley.

Scientists confirmed the trade off in a paper published in the Journal of Experimental Botany, showing the gene had the effect of increasing barley’s susceptibility to ramularia.

“It has struck us that plant breeding relying on the successful use of a single major resistance gene can increase susceptibility to another disease.”
KWS UK plant breeder Peter Werner

The research has paved the way for future breeding developments with barley lines that are bred to be resistant to both diseases.

“It has struck us that plant breeding relying on the successful use of a single major resistance gene can increase susceptibility to another disease,” said plant breeder Peter Werner from KWS UK.

“We have been observing more ramularia than in the past and now that we know what is happening on a genetic level we can do something about it,” he explained.

The research was supported by the Biotechnology and Biological Sciences Research Council, the Scottish Government’s Rural and Environment Science and Analytical Services Division, AHDB-HGCA and a consortium of 10 companies through DEFRA’s Sustainable Arable LINK programme.

(More on disease in winter wheat)