Pathotypic and molecular evolution of contemporary population of Puccinia striiformis f. sp. tritici in Egypt during 2016–2018

Abstract

The contemporary races of Puccinia striiformis f. sp. tritici (Pst) in Egypt during 2016–2018 were differentiated based on virulence and molecular patterns. Virulence patterns based on the reaction of the 17 World/European differential sets carrying stripe rust resistance genes (Yr genes) resulted in ten races including four new (first recorded in Egypt) and six old (previously recorded in Egypt). The new races were identified as 64E0 (virulence [V] Yr4, Su), 0E16 (V Yr8, 19), 66E0 (V Yr4, 7, 22, 23, Su) and 4E130 (V Yr2, 6, 7, 25, HVII), while the old were 0E0 (avirulence), 2E0 (V Yr7, 22, 23), 2E16 (V Yr7, 8, 19, 22, 23), 4E0 (V Yr2, 6), 6E4 (V Yr2, 6, 7, 22, 23, 25) and 70E4 (V Yr2, 4, 6, 7, 22, 23, 25, Su). Cluster analysis differentiated Pst races based on virulence frequency to Yr genes. Simple sequence repeat (SSR) markers were used to detect the molecular polymorphism of the Pst races. Clustering separated the old and new races into two groups, indicating their common ancestry since the new races were very distinct from the old races. Although clustering based on virulence revealed some evolutionary patterns, where the new races 64E0 and 66E0 may have probably evolved from the old races (2E16, 2E0, 6E4, 70E4) and the new race 4E130 may be evolved from the joint race 4E0. However, clustering based on molecular patterns indicated that the new races appear to be genetically distinct and may represent an exotic introduction rather than a mutation in isolates of the old races. A weak association between virulence and molecular patterns revealed that they are independent of each other. The SSR markers did not correspond to the virulences in the pathogen. Further studies on the potential virulence genes of the detected Pst virulences are needed.

Changeability in Stripe Rust Infection and Grain Yield of Wheat Associated to Climatic Conditions

“…The field resistance level of a set of numerous varieties/breeding lines is assessed through their severity and host reaction at adult plant stage. Host reaction is the phenotype resulting from the interaction after Pst infection as responded by the host defense mechanism and is termed a hostpathogen interaction phenotype (Draz 2019). The ability of stripe rust to infect wheat plants depends on many factors, including host resistance, time of infection, and environmental factors (Sharma-Env.…”

Race specificity of stripe rust resistance in relation to susceptibility of Egyptian wheat cultivars

“…tritici population from avirulent to virulent, overcoming the race-specific all-stage resistance (Liu et al, 2019). The evolution of Pst races in Egypt during 2016-2018 has been reported with new virulent races which were used in the present study (Draz et al, 2019;Draz, 2019).…”

“…Twelve Pst races, 64E0, 0E16, 66E0, 4E130, 2E0, 2E16, 4E0, 6E4, 70E4, PstS2, PstS3 and Triticale aggressive reported in our previous study during 2016-2018 in Egypt (Draz et al, 2019;Draz, 2019) were used in this study. The 12 Pst races have virulence spectra to the tested Yr genes as shown in Table (2).…”

Genetic diversity of Puccinia kuehnii, the causal agent of orange rust of sugarcane, from Brazil

“…In this sense, one important step of breeding programmes to avoid cryptic error is increase the number of susceptible cultivars employed as spreader of P. kuehnii during selection of breeding lines, usually only one is employed (Chapola et al, 2016). to the one produced by the existing pathogen races (Draz, 2019).…”