Browsing by Subject "Race-specific resistances"

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    Wirkung rassenspezifischer Braunrostresistenzen in genetisch diversifizierten Roggenpopulationen
    (2004) Wilde, Katinka; Miedaner, Thomas
    Leaf rust (Puccinia recondita f.sp. secalis) is the most frequently occuring leaf disease in German winter rye (Secale cereale L.). To test the usefulness and potentially prolong the durability of race-specific resistance genes, we increased host complexity and diversity by producing synthetic (Syn) populations segregating for one to four resistance sources as a model system for hybrid varieties. Thirty synthetics were grown together with three highly susceptible synthetics as checks, two Russian full-sib families (FSF), a leaf-rust-resistant-hybrid variety, a set of 17 differential genotypes and ten parental lines at six locations in three years (17 environments) in Germany under natural infection. The parental lines were only sown in 11 environments. Disease severity of about 120 plants for each synthetic, FSF, hybrid and about 25 plants for each differential genotype and parental line was estimated as percentage of infected leaf area on the leaf below the flag leaf at the mid and the end of the natural epidemic. Susceptible synthetics showed that disease severity was similarly high in all environments. Only two out of 30 synthetics and both FSF were resistant across 17 environments. Low resistance of the synthetic was caused by the low resistance of the parental lines. Nonetheless, some of the synthetics were more resistant than the tested commercial hybrid variety. Even though the resistance was not used in practical breeding programs to date we detected virulence for each resistance gene tested. In conclusion, the German leaf rust population seems to be highly diverse and none of the self-fertile resistance sources used provided full protection. New race-specific resistances or highly effective quantitative resistances are therefore needed and should be combined.