RYE RESISTANCE TO BROWN RUST AND POWDERY MILDEW - THE POTENTIAL OF HEREDITARY VARIABILITY

Genetic diversity in rye with respect to resistance to brown rust and powdery mildew was studied. Plants resistant to brown rust and powdery mildew were revealed in 38 and 4 cultivars of winter rye, respectivel y. In each case, resistance to the diseases was shown to be controlled by a dominant allele of a single gene. A method of gene identificatio n was proposed that can be used when a resistance trait is controlled by a dominant allele of a single gene. Resistance to a population of b rown rust was for the first time demonstrated to be controlled by the genes Pd (in rye cultivars Sanim, I-125/79, Baltiiskaya RPd, and Chern igovskaya RPd) and Pd1 (Immunnaya 1). Brown rust resistance in the cul tivar Chulpan RPd appeared to be determined by a gene that was nonalle lic to Pd (temporarily designated Pd3). To confirm the proposed hypoth esis, further experiments, establishing nonallelic relations between t he genes Pd3 and Pd1, are required. In compliance with international s tandards, the genes Pd, Pd1, and Pd3 were given the new names Lr4, Lr5 , and Lr6, respectively.