Abstract

Walid M. El-Orabey, Minaas E. Sallam, Reda I. Omara and Nagwa I. Abd El-Malik

Wheat leaf rust caused by Puccinia triticina Eriks. is a common disease in Egypt and worldwide. Survey of wheat leaf rust samples and identification of physiological races using twenty single Lr genes are very important in describing virulence pattern variation, geographical distribution of leaf rust pathotypes and how its change in response to host selection. Variability in population of the causal organism is annually determined using samples collected from wheat growing areas in Egypt for three growing seasons that is, 2011/2012, 2012/2013 and 2013/2014. The results obtained showed a significant variability in pathotypes which are different from season to season. In the course of this study a total of 50, 65 and 33 leaf rust samples were collected in 2011/2012, 2012/2013 and 2013/2014, respectively from different wheat growing areas in eight governorates of Egypt that is, Beheira, Dakahlia, Gharbiya, Minufiya, Sharqiya, Domiatta, Qalyubiya and BaniSweif. A total of 118, 166 and 61 physiologic races were identified in 2011/2012, 2012/2013 and 2013/2014, respectively. The most frequent races included STTST and TKTTT (each with 2.54%) in 2011/2012; PKTST (6.63%), TTTTT (7.83%) and TTTST (10.24%) in 2012/2013 as well as FKTTT (4.92%) and PTTTT (11.47%) in 2013/2014. Race groups PT--- and TK--- were common at eight locations during the three growing seasons. Cluster analysis based on percentage frequency of virulence of P. triticina race groups in different location showed that in 2011/2012 and 2012/2013 growing seasons two main clusters were formed. While, in 2013/2014 growing season the cluster analysis was divided into six main clusters. Lines with Lr 1, Lr 2c, Lr 3, Lr 16, Lr 24 and Lr 26 were susceptible against most race groups, while, the leaf rust monogenic lines Lr 2a and Lr 9 showed different reactions against the tested race groups.