This has been a bad year for farmers: last year’s wet summer and then the cold winter that just won’t end have scuppered one harvest and probably knocked this year’s right down too. Even when conditions are more ideal than they have been this year, farmers and breeders fight an uphill battle trying to prevent a significant proportion of the crop being lost to various pathogens. When it comes to wheat that means rust: black rust, brown rust and yellow rust. Where it strikes, yield losses are likely to be around 20% in susceptible varieties, and the problem is getting much worse. Most resistance to black rust (Puccinia triticina) is caused by a single gene, which a new resistant kind of rust (Ug99) managed to overcome in much the same way as MRSA became resistant to methicillin in our hospitals.
Now scientists from Norwich, Cambridge and the USA are trying to find out how some kinds of a similar disease, yellow rust, (Puccinia striiformis or PST) are able to overcome the plant’s natural defences and infect. Continue reading