Geographical distribution of Puccinia triticina physiologic races in Egypt during 2012-2014 growing seasons

Abstract

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 using twenty single Lr genes for three growing seasons i.e. 2011/12, 2012/13 and 2013/14. 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 2011/12, 2012/13 and 2013/14, respectively from different wheat growing areas in eight governorates of Egypt i.e. Beheira, Dakahlia, Gharbiya, Minufiya, Sharqiya, Domiatta, Qalyubia and Bani Sweif. A total of 118, 166 and 61 physiologic races were identified in 2011/12, 2012/13 and 2013/14, respectively. The most frequent races included STTST and TKTTT (each with 2.54%) in 2011/12; PKTST (6.63%), TTTTT (7.83%) and TTTST (10.24%) in 2012/13 as well as FKTTT (4.92%) and PTTTT (11.47%) in 2013/14. 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 2011/12 and 2012/13 growing seasons two main clusters were formed. While, in 2013/14 growing season the cluster analysis 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.