Specific resistance factors to yellow rust in seedlings of some French wheat varieties and races of Puccinia striiformis Westend in France

Abstract

Infection types in Triticum aestivum L seedlings induced by 9 French races of Puccinia striiformisWestend were used to assess the hypothetical content of specific genes for resistance to yellow rust in 21 wheatvarieties widely grown in France. Resistance to the race 0E0 showed that none of the varieties lacked resistancefactors. Most of the varieties possessed only 1 to 3 known Yr genes. The postulated genes were Yr 1, Yr 2,(Yr3a + Yr4a), Yr6 and Yr7. The varieties Festival, Fidel, Beauchamp, Gala, Castan, Scipion, Caton, Darius, Top,Soissons, and Thésée may carry one or more resistance factors belonging to the set of SD (Strubes Dickkopf), Yr 2,and (Yr 3a + Yr 4a). Further hypotheses were developed with the use of British races. Top was postulated to possess(Yr 3a + Yr 4a) and Darius to have Yr 2. Yr 7 was postulated in Prinqual, Talent, and Tango. Corin probably possessesYr 1 and might also carry Yr 2 and/or ( Yr 3a + Yr 4a). Garant and Hardi may possess Yr 7 7 and Yr 2 or ( Yr 3a + Yr 4a).Récital and Austerlitz had reactions consistent with the presence of Yr 6, and the latter may have an extra gene. CampRémy and Arminda were resistant to all races tested. Surveys of P striiformis showed the importance of races whosevirulence spectra were able to match most of these resistance genes. Two races (45E140 and 45E172) were mostlyresponsible for the 1987 and 1988 epidemics; 3 others (41 E136, 109E141, and 109E173) were also important.