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Transmission of the rye 2R chromosome in backcrosses of wheat-rye substitution lines 2R(2D) 1 , 2R(2D) 2 , and2R(2D) 3 (Triticum aestivum L. cv. Saratovskaya 29 / Secale cereale L. cv. Onokhoiskaya, 2n = 42) to common wheat varieties Saratovskaya 29 (S29), Novosibirskaya 67 (N67), and line Lutescens 307/97 23 (Lut307) has been studied. Rye chromosomes are present in the progeny of hybridsLut307 × 2R(2D) 1 in the disomic or monosomic states; telocentrics and 2R/2D translocations have been recorded as well. The frequency and mode of 2R chromosome transmission are influenced by the gen otypes of both the wheat-rye substitution line and the recurrent variety. In the backcrossing to N67, rye chro mosomes of lines 2R(2D) 1 and 2R(2D) 3 replace the 2D chromosome more often than in crosses to Lut307 or S29. Chromosomes with aberrations were found in 26% of the hybrids after the first backcross. In the recip rocal cross of 2R(2D) 1 to Lut307, the 2R chromosome was found only in two plants. Putative mechanisms that are responsible for translocations between homological chromosomes of wheat and rye are considered.