Evaluation of Advance Wheat Lines for Slow Yellow Rusting (Puccinia striiformis f. sp. Tritici)

Stripe rust (yellow rust), caused by Puccinia striiformis f. sp. tritici is one of the most damaging diseases of wheat in Pakistan. Lack of durable resistance in local wheat varieties is the main reason for stripe rust epidemic which could limit yields. The use of genetically resistant wheat varieties is the most economic way of controlling the disease. Evaluation of 135 advance wheat lines for slow yellow rusting was conducted during cropping season 2008-2009 under natural epidemics at field locations of Ayub Agriculture Research Institute, Faisalabad and Cereal Crops Research Institute, Pirsabak (Northwest), Pakistan. Resistance level based on final disease severity (FDS) along with other slow rusting parameters relative area under disease progress curve (rAUDPC) and relative infection rate (RIR) was assessed. A total of 25 wheat lines were identified to potentially have durable resistance with low frequency of disease severity (10-30%) and lower relative AUDPC values (2-66%). Based on the slowing rusting data, RAPD (random amplified polymorphic DNA) primers were used in order to evaluate genetic diversity among 25 lines. Of 20 OPA (Operon series) primers tested, 4 (20%) primers were polymorphic that showed amplification differences among 25 genotypes. OPA-06 and OPA-04 revealed the highest polymorphism (67% and 50%) while OPA-02 and OPA-17 exhibited the lowest polymorphism (33% and 25%) respectively. From the amplification profile, a total of five RAPD markers were obtained in this study. A similarity matrix data depicted that most of these genotypes are genetically very close (60-100%). The 25 advance lines identified from slow rusting evaluation with five RAPD markers may have partial resistance genes and can be used as slow yellow rusting lines with longer field life in Pakistan breeding program.