Problems of winter rye breeding for resistance to leaf and stem rusts

Since 1967, over 2,500 rye (Secale cereale L. and S. montanum Guss.) populations have been studied at the N.I.Vavilov Research Institute of Plant Industry in order to determine genetic diversity of the crop with respect to leaf rust (Puccinia recondita Rob.) resistance. Plants possessing race-specific resistance to leaf rust were found in 51 accessions (cultivars, landraces and wild species). In 2000, a study of 420 rye accessions revealed stem rust (Puccinia graminis Pers. f. sp. secalis Erikss. et Henn.) resistant genotypes in 69 of them. Control of leaf rust resistance was found to be dominant monogenic in 44 accessions, and digenic in cultivar Chulpan 2. In some accessions, e.g. Avangard 2, Novozybkovskaya 4-2 and Derzhavinskaya 2, leaf rust resistance of individual plants was determined by one dominant gene, while in other plants of the same accessions it was determined by two dominant genes. In most resistance sources (Sanim, Chernigovskaya 3, Kharkovskaya 55) genetic control of the character is determined by the Lr4 gene, in Jmmunnaya 1 by Lr5, in Chulpan 3 and Immunnaya 4 by Lr6, in Novozybkovskaya 4-2 by Lr7, and in Lovaszpatonai by Lr8, in Yaroslavna 3 by LriO. Stem rust resistance is controlled by the dominant gene Sri. By pyramiding effective resistance genes two new winter rye cultivars have been bred.These are Estafeta Tatarstana (1999) and Era (2001) characterized by a high-level resistance to leaf and stem rust, to powdery mildew.