Virulence surveys of wheat leaf rust in the Czech Republic and resistance genes in registered cultivars

The technical report presents a summary of results obtained in the leaf rust race surveys carried out in Czechoslovakia/Czech Republic in the years 1966–2001. The physiologic races were determined using the standard differentials Malakoff (Lr1), Carina (Lr2b), Brevit (Lr2c), Webster (Lr2a), Loros (Lr2c), Mediterranean (Lr3), Hussar (Lr11), Democrat (Lr3) and the additional differential Salzmünder Bartweizen (Lr26). Races 14, 77, 61, 53 and 2  successively dominated in the given period. They mostly appeared in two variants, avirulent and virulent to Lr26. Genes for virulence in the leaf rust races were compared with genes for resistance in the registered wheat cultivars listed in the report. Most frequent were the genes Lr3 and Lr26.

Geographical Distribution of Physiologic Races of Puccinia triticina and Postulation of Resistance Genes in New Wheat Cultivars in Egypt

Knowledge of the geographical distribution for physiologic races of Puccinia triticina and identification of leaf rust resistance genes (Lr ,s) in the recent Egyptian wheat cultivars are essential for maximizing resistance in future-bred cultivars. The aim of this study was to know the status of resistance in Egyptian wheat cultivars against wheat leaf rust and the most frequent race distributed. Infected samples were collected from five Governorates, i.e., Dakahlia, Kafr el-Sheikh, Beheira, Sharqia and Sohag comprised the wheat growing area in Egypt. These samples were isolated, purified and identified on the differential stes. Gene postulation was done using fifteen identified races on Egyptian wheat cultivars correlated with Lr genes. Thirty three races identified during three seasons 2009/2010, 2010/2011 and 2011/2012. The most frequent race was TK (10%) followed by race BB (7.58%), PK (6.55%), TT (4.82%), PT (3.79%) and MT (3.44%). Moreover, races; BB, TT and PT were present during three seasons while these races appeared in some Governorates and disappeared in other Governorates. On the other hand, the most frequently occurring gene in ten Egyptian wheat cultivars was Lr35 (70%), followed by Lr22 (60%), Lr27 (40%), Lr34 (30%), Lr19 (30%),Lr18 (10%),Lr36 (10%) and Lr46 (10%), eight out of sixteen Lr genes were not present in the tested cultivars. It is concluded that there was a good variation in Lr genes carried by wheat cultivars commercially grown in Egypt. Therefore, strategies for deploying resistance genes to prolong effective disease resistance are suggested to control wheat leaf rust disease.

Physiologic Specialization of Wheat Leaf Rust (Puccinia triticina Eriks.) in theCzech Republic in 2001–2004

In 2001–2004 virulence of the wheat leaf rust population in the Czech Republic was studied on Thatcher near-isogenic lines with Lr1, Lr2a, Lr2b, Lr2c, Lr3a, Lr9, Lr10, Lr11, Lr15, Lr17, Lr19, Lr21, Lr23, Lr24, Lr26 and Lr28. Samples of leaf rust (180 in total) were obtained from different parts of the Czech Republic. Resistance genes Lr9 and Lr19 were effective to all tested isolates like in the previous years. Unlike the previous years virulence on Lr24 and Lr28 was observed. Relatively effective were also Lr1, Lr2a, Lr24, Lr28 and Lr2b. Other Lr genes were defeated by the majority of the tested samples. Our results transformed to the numbers of physiologic races indicate that race 61SaBa prevailed like in the previous years, followed by races 61, 2, 12SaBa, 2SaBa, 14, 77SaBa, 12, 57, 6, 53, 53SaBa, 77, and 14SaBa. Twenty-one winter wheat cultivars registered in 2001–2004 were tested with 8 leaf rust isolates. Out of them 15 showed resistance at least to one rust isolate. High resistance recorded in field trials for cvs Batis and Ilias, which were susceptible to all tested rust isolates at the seedling stage, demonstrates the importance of field (partial) resistance.