Leaf Rust of Cultivated Barley: Pathology and Control

Abstract

Leaf rust of barley is caused by the macrocyclic, heteroecious rust pathogen Puccinia hordei, with aecia reported from selected species of the genera Ornithogalum, Leopoldia, and Dipcadi, and uredinia and telia occurring on Hordeum vulgare, H. vulgare ssp. spontaneum, Hordeum bulbosum, and Hordeum murinum, on which distinct parasitic specialization occurs. Although Puccinia hordei is sporadic in its occurrence, it is probably the most common and widely distributed rust disease of barley. Leaf rust has increased in importance in recent decades in temperate barley-growing regions, presumably because of more intensive agricultural practices. Although total crop loss does not occur, under epidemic conditions yield reductions of up to 62% have been reported in susceptible varieties. Leaf rust is primarily controlled by the use of resistant cultivars, and, to date, 21 seedling resistance genes and two adult plant resistance (APR) genes have been identified. Virulence has been detected for most seedling resistance genes but is unknown for the APR genes Rph20 and Rph23. Other potentially new sources of APR have been reported, and additivity has been described for some of these resistances. Approaches to achieving durable resistance to leaf rust in barley are discussed.

Rapid phenotyping of adult plant resistance in barley (Hordeum vulgare) to leaf rust under controlled conditions

“…Plants were maintained at either 18 or 23°C in separate greenhouse microclimate chambers. Disease response was measured 9 days post‐inoculation using a modified Stakman “0–4” scale (Park et al., ). Both plants in each well were scored separately as were the two trays in each temperature treatment.…”

“…is an economically significant disease in the major cereal production regions worldwide (Clifford, ). In Australian barley crops, leaf rust is the most common and damaging of the rust diseases (Park et al., ). It has been estimated to cost Australian barley growers $21 million per annum, with yield losses of up to 62% in untreated susceptible varieties (Cotterill, Rees, Platz, & Dillmacky, ; Murray & Brennan, ).…”

“…To date, 26 leaf rust resistance ( Rph ) genes have been designated. Two classes of Rph genes are recognized: all stage resistance (ASR) genes ( Rph1‐19, 21, 22, 25 and 26) and adult plant resistance (APR) genes ( Rph20, 23 and 24) (Kavanagh, Singh, Bansal, & Park, ; Park et al., ; Ziems et al., ). Lines that carry APR genes are seedling susceptible, but as adult plants show a medium to strong reduction in the number and size of pustules (Smit & Parlevliet, ).…”

Inheritance and characterization of the new and rare gene Rph25 conferring seedling resistance in Hordeum vulgare against Puccinia hordei

“…tritici and secalis (commonly known as the “scabrum” rust; Park & Wellings, ). Of the three rusts of barley, leaf rust is the most damaging not just in Australia but in many other barley growing regions of Europe, North Africa, South America and the United States, and it has been estimated to cause yield losses of 30%–40% in susceptible cultivars (Park et al., ). The most sustainable and economical control of Ph is through the deployment of resistance genes, estimated by Murray and Brennan () to save Australian barley growers some AUD 47 million per year.…”

Pathogenic and genetic diversity in Puccinia hordei Otth in Australasia

“…While no virulence was detected in these studies for genes Rph3, Rph7, Rph11, Rph14, Rph15 and Rph18 (Park, 2003), virulence for Rph3 was detected in 2009 (pt 5457P + ) in northern New South Wales (NSW) (Park, 2010). This pathotype is believed to have arisen from pt 5453P -, first detected in Western Australia in 2001 (Park, 2006), via sequential single step mutations for virulence to Rph19 (pt 5453P + ) and then Rph3 (pt 5457P + ) (Park et al, 2015;Park, 2010).…”