Phenotypic and Molecular Characterization of Wheat for Slow Rusting Resistance against Puccinia striiformis Westend. f.sp tritici

Race-specific resistance of wheat (Triticum aestivum L.) to yellow rust caused by Puccinia striiformis Westend. f.sp. tritici is often short-lived. Slow-rusting resistance has been reported to be a more durable type of resistance. A set of sixteen bread wheat varieties along with a susceptible control Morocco was tested during 2004-05 to 2006-07 in field plots at Peshawar (Pakistan) to identify slow rusting genotypes through epidemiological variables including final rust severity (FRS), apparent infection rate (r), area under disease progress curve (AUDPC), average coefficients of infection (ACI) and leaf tip necrosis (LTN). Epidemiological parameters of resistance were significantly (P < 0.01) different for years/varieties in three seasons, while variety x year interactions remained non-significant. Sequence tagged site (STS) marker, csLV34 analyses revealed that cultivars Faisalabad-83, Bahawalpur-95, Suleman-96, Punjab-96, Bakhtawar-93, Faisalabad-85, Shahkar-95 and Kohsar-95 possessed Yr18 linked allele. Faisalabad-83, Bahawalpur-95, Suleman-96, Punjab-96, Bakhtawar-93 and Faisalabad-85 were relatively more stable over 3-years where FRS, AUDPC and r values reduced by 80, 84 and 70% respectively compared to control Morocco. These six varieties therefore could be exploited for the deployment of Yr18 in breeding for slow rusting in wheat. Both FRS and ACI are suitable parameters for phenotypic selection.