Virulence patterns of barley yellow rust and effective resistance genes to Puccinia striiformis in three parts of Iran

Stripe rust of barley (Hordeum vulgare L.), caused by Puccinia striiformis f. sp. hordei, is a serious problem of barley production in many parts of the world. Monitoring of the pathogen virulence factors and their changes provides basic information for development of an early warning system to breeders and researchers. To monitor the regular virulence changes, trap nurseries comprising of 12 barley differential sets were planted at different parts of Iran in six consecutive years 2007–2012. When the infection and severity under natural infection on susceptible cultivar Afzal as the check was high, then the response of each line was assessed using modified Cobbs scale. Results revealed that no virulence was observed on plants with resistance genes rpsEm1, rpsEm2, rpsHF, Rps4, rpsVa1, rpsVa2 and rpsAst. Therefore, these genes were considered effective genes and can be used to pyramid with those for race-non-specific resistance genes to achieve more durable and highly effective resistance to stripe rust. The plants with the resistance genes rps2, Rps1.b, Rps3 and rpsI5 showed susceptible reaction and virulence was observed on them, thus their resistance genes were considered ineffective.