Identification and Characterization of the Gene Conditioning Powdery Mildew Resistance in ‘Amigo’ Wheat1

Abstract

‘Amigo’ wheat (Triticum aestivum L.), is a source of genetic resistance to greenbug (Schizaphis graminum Rondani) biotype C, and is reportedly resistant to powdery mildew (Erysiphe graminis D.C. ex. Merat. f. sp. tritici Em. Marchal). The objective of this research was to identify and characterize the gene(s) for powdery mildew resistance in Amigo wheat To verify that Amigo is resistant to powdery mildew, selected lines from a near‐isogenic series carrying genes conditioning powdery mildew resistance, and ‘Kavkaz’, Amigo, and ‘Chancellor’ wheats were inoculated with culture 3 of E. graminis tritici and observed for disease reaction. Kavkaz is mildew resistant and Chancellor is known to be susceptible to powdery mildew. Crosses were made between Amigo and Chancellor, and between Amigo and the lines from the near‐isogenic series and Kavkaz. Resulting F2 plants were inoculated with culture 3 of E. graminis tritici and rated for resistance. Results from the screening procedures confirmed that Amigo is mildew resistant and that resistance is conferred by a single dominant gene. The segregation ratios for the F2 populations of Amigo/isogenic series and Amigo/Kavkaz suggest the Amigo gene conferring mildew resistance is previously unreported. A possible linkage relationship between the genes for powdery mildew resistance in Amigo and ‘Asosan/8*Chancellor’ was tested. The F2 families of the cross Amigo/2/Asosan/8*Chancellor were inoculated with E. graminis tritici culture 3 and segregation ratios observed. Close linkage between the genes for resistance in Amigo and Asosan/8*Chancellor was confirmed.