Pathotypes and Physiologic Races of Puccinia triticina Eriks. The Causal Agent of Wheat Leaf Rust and Their Distribution in Iran in 2009 and 2010

In order to study the pathogenic variability in Puccinia triticina Eriks (Pt)، population and for identification of physiological races، during early spring of 2009 and 2010، more than 140 infected leaf samples were collected randomly from different wheat growing areas in Iran. In each sample، some single pustules were produced. In total 234 single pustules were used for seedling race analysis of which، 177different virulence classes (races) were identified. Three leaf rust races FKTRS، FJRRS، and FKTTS were highly frequent among identified races. The maximum number of virulence factor for 31 Lr genes was found for races TKTTN and TFTTN that were collected form Ardebil and North Khorasan، respectively. In spite of the high diversity in Pt population in Iran، gene Lr19 was susceptible only to one race (FHQJS) and Lr2a to seven races. Based on the results of this study، combination of leaf rust resistance gens with low frequency of virulence (such as Lr9، Lr28، Lr25، Lr19، Lr29، and Lr2a) with the Non-race specific adult-plant resistance genes (Lr34، Lr46or Lr67) could be used for development of durable leaf rust resistant cultivars. Existence of the identical races especially in the adjacent provinces along with the existence of air flows on this way reinforced the reason of linking of these provinces through air flows. This relationship was both in grouping based on being virulent or non-virulent on the seedlings of wheat near isogenic lines and in the abundance of the races. The aggressive isolates in rather similar groups showed the relation between the provinces. Almost most of the provinces were related to each other. This suggests the vast gene flow and effective transmission of spores through air flows.