Geographical Correlation and Genetic Diversity of Newly Emerged Races within the Ug99 Lineage of Stem Rust Pathogen, Puccinia graminis f. sp. tritici, in Different Wheat-Producing Areas

Abstract

Wheat stem rust caused by Puccinia graminis f. sp. tritici is one of the most destructive wheat diseases worldwide. Identifying stem rust races in general, Ug99 lineage particularly, and determining resistance genes are critical goals for disease assessment. Thirty wheat varieties and monogenic lines with major stem rust resistance genes (Sr) were examined here over the course of three succeeding seasons from 2020 to 2022. Fourteen stem rust races have been identified in ten African countries, as well as Central and West Asia and North Africa (CWANA) and ten European countries. The Ug99 group (Clade I) included four races (TTKSK, TTKST, TTKTK, and TTKTT) and was reported in five African countries (Egypt, Kenya, Rwanda, Tanzania, and Uganda) and Iran, but none of the European countries. On the other hand, none of the races in Clade III-B (TTRTF) and Clade IV-B (TKTTF and TTTTF) were found in Egypt. Furthermore, Egyptian races were clustered separately from races identified from other countries, and six races were found only in Egypt, including PKSTC, RKTTH, TKTTC, TTTSK, TCKTC, and TKTTH. Races from Kenya, Tanzania, Uganda, Rwanda, and Iran were all closely associated with one another, according to correlation analysis. However, most races identified from other investigated regions, including Eritrea, Spain, Ethiopia, Morocco, Italy, Poland, Kenya, Tanzania, and Uganda, were adversely linked with Egyptian races. The diagnostic 350 bp long PCR fragment linked with virulence to Sr31, Clement (Sr31), and Brigardier (Sr31) was used to identify the TTKSK (Ug99) race. The identification of the regional associations and genetic diversity of newly emerged races within the Ug99 lineage of P. graminis tritici in Africa, Asia, and Europe is one of the key goals of this study. It will help plant breeders to develop new resistant lines against the virulent races, especially TTKSK (Ug99) and TTTSK. This helps in ensuring global food security in the context of climate change.

Genome-wide association mapping highlights candidate genes and immune genotypes for net blotch and powdery mildew resistance in barley

“…Moreover, none of the significant markers for PM and NB detected in this study were previously reported in earlier studies. This could be due to the races that may differ by graphical region [67] . Also, race for the same region could differ by year due to the emergence of new races by mutations [67] .…”

“…This could be due to the races that may differ by graphical region [67] . Also, race for the same region could differ by year due to the emergence of new races by mutations [67] . As each race is probably controlled by different genes, it is expected that the genes that are resistant to the Egyptian races of NB and PM could be different from those that were resistant to other races reported in earlier studies.…”

Effects of gamma rays on rusts, yield and seed quality of some wheat genotypes

“…Wheat production is influenced by yellow and leaf rust, which produce considerable grain yield losses due to their ability to form new races, wide dispersion, and ability to spread over large distances (Hasan et al, 2016;Gebril et al, 2018a, b;El-Orabey et al, 2019;Gad et al, 2019 a, b;Gebrel et al, 2019;El-Naggar et al, 2020;Gad et al, 2020;Gebrel et al, 2020;Shahin et al, 2022). During 2020/2021 and 2021/2022 growing seasons, the performance of five bread wheat genotypes was evaluated for rusts control, yield components, and seedling parameters by their exposure to five doses of gamma rays i.e.…”