The wheat tan spot pathosystem in Australia: A showcase of effector‐assisted breeding

Abstract

AbstractTan spot disease of wheat (also known as yellow spot) is caused by the necrotrophic fungal pathogen Pyrenophora tritici‐repentis (Ptr). Initially described as a grass pathogen, Ptr has become a wheat pathogen of global importance. In Australia, tan spot was first recorded in 1952 as a minor wheat disease. However, by the 1970s tan spot had reached epidemic levels in Australia with yield losses of up to 49% reported in the north‐eastern region. A national survey carried out in 2007/2008 placed tan spot as the most economically important wheat disease with an estimated yield loss of 6%, corresponding to nearly a quarter of all disease losses. The incidence of tan spot in Australia has now markedly reduced with some wheat breeding programmes no longer considering tan spot disease resistance to be a priority trait. The disease can be effectively managed with integrated control strategies such as crop rotation, timely application of fungicides and removal of surface stubble. However, the key to the success of controlling tan spot disease in Australia has been achieved through wheat breeding programmes. The development of tan spot resistance resources suitable for the Australian climate was a concerted effort between national and international research organizations and Australian wheat breeders, supported by the Australian Grains Research Development Corporation (GRDC). While traditional breeding was essential to combat the disease, this article highlights the value of effector biology in assisting the development of resistant cultivars.