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Research Project: Genetic Improvement of Small Grains for Biotic and Abiotic Stress Tolerance and Characterization of Pathogen Populations

Location: Plant Science Research

Title: Virulence of Egyptian blumeria graminis f. sp. tritici population and powdery mildew response of Egyptian wheat cultivars

Author
item ABDELRHIM, ABDELRAZEK - Minia University
item ABD-ALLA, HARBY - Minia University
item ABDOU, EL-SAYED - Minia University
item ISMAIL, MAMDOUH - Minia University
item Cowger, Christina

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/12/2017
Publication Date: 1/30/2018
Citation: Abdelrhim, A., Abd-Alla, H.M., Abdou, E., Ismail, M.E., Cowger, C. 2018. Virulence of Egyptian blumeria graminis f. sp. tritici population and powdery mildew response of Egyptian wheat cultivars. Plant Disease. 102:391-397.

Interpretive Summary: Powdery mildew caused by the fungus Blumeria graminis f. sp. tritici is a serious disease of wheat that can cause a severe reduction in yield. In Egypt, high powdery mildew severity has been observed in the past few years on many commercial cultivars of both bread and durum wheat. Little information is available about the virulence of the Egyptian B. graminis f. sp. tritici population in Egypt or the response of Egyptian wheat cultivars to powdery mildew. Virulence frequencies from seven provinces were chosen to represent the country: two in Upper Egypt (Qena and Sohag), one in Middle Egypt, (El Minia) and four in the north (Alexandria, Kafr Elsheikh, Dakahlia and Sharqia). Ten isolates from each province were obtained from single spores and used for this study. They were inoculated individually on 21 wheat lines, each bearing a single resistance (Pm) gene. Also, the responses of 14 Egyptian bread wheat cultivars and 6 durum cultivars to each of the 70 isolates were evaluated individually. Among all tested Pm genes, only seven (Pm1b, Pm2, Pm21, Pm34, Pm36, Pm37, and Pm53) were effective against B. graminis f. sp. tritici isolates from all regions. Several other genes were effective against most or all isolates from a majority of provinces. All tested bread wheat cultivars showed full susceptibility to all isolates, while two durum wheat cultivars, Beni-Suef-5 and Beni-Suef-6, had intermediate responses to a large percentage of the isolates, likely indicating partial resistance. To enhance mildew resistance in Egyptian wheat cultivars, it is recommended to use combinations of genes that are nationally effective or effective against multiple provincial B. graminis f. sp. tritici populations.

Technical Abstract: Powdery mildew caused by Blumeria graminis (DC.) Speer f. sp. tritici (Em. Marchal) is a serious disease of wheat that can cause a severe reduction in yield. In Egypt, high powdery mildew severity has been observed in the past few years on many commercial cultivars of both bread and durum wheat. Little information is available about the virulence of the Egyptian B. graminis f. sp. tritici population in Egypt or the response of Egyptian wheat cultivars to powdery mildew. Virulence frequencies of a representative sample of the Egyptian B. graminis f. sp. tritici population were studied. Seven provinces were chosen to represent the country: two in Upper Egypt (Qena and Sohag), one in Middle Egypt, (El Minia) and four in the north (Alexandria, Kafr Elsheikh, Dakahlia and Sharqia). Ten isolates from each province, or 70 isolates total, were derived from single ascospores and used for this study. They were inoculated individually on 21 powdery mildew differential lines, each bearing a single resistance (Pm) gene. Also, the responses of 14 Egyptian bread wheat cultivars and 6 durum cultivars to each of the 70 isolates were evaluated individually. Among all tested Pm genes, only seven (Pm1b, Pm2, Pm21, Pm34, Pm36, Pm37, and Pm53) were effective against B. graminis f. sp. tritici isolates from all regions. Several other genes were effective against most or all isolates from a majority of provinces. All tested bread wheat cultivars showed full susceptibility to all isolates, while two durum wheat cultivars, Beni-Suef-5 and Beni-Suef-6, had intermediate responses to a large percentage of the isolates, likely indicating partial resistance. To enhance mildew resistance in Egyptian wheat cultivars, it is recommended to use combinations of genes that are nationally effective or effective against multiple provincial B. graminis f. sp. tritici populations.