Tetraploid triticale as a potential source of new variation for rye

High crossability of tetraploid triticale (X Triticosecale Wittmack) with rye (Secale cereale L.) and relatively high fertility of the resulting hybrids make the triticale an attractive bridge species for introduction of wheat genes into rye breeding populations. It was found, with the use of in situ hybridization technique, that some 4x triticale materials bred in Radzików contain small wheat translocations, of both distal and intercalary type, into the rye 5R chromosome. The distal wheat translocation occupying less than 5% of the long arm was transferred into diploid rye, but a disomic line has not been established yet. Other wheat translocations of the chromosomes 1R and 5R were found in hybrids of 4x rye with 4x triticale. Besides the intergenomic crossing-over, at least one another mechanism of DNA rearrangements operated. Small intercalary two-dot signals of the wheat fluorescent probe were also found in one line on a rye chromosome different than 5R. Most puzzling was the „invisible” migration of wheat DNA to rye chromosomes, detectable on southern dot-blots, but not on the in situ slides. The wheat probe dot-blot signals were recorded for more than 1/3 of rye plants from the first back-cross of the 4x triticale × 2x rye hybrids to rye.