TETRAPLOID TRITICALE AS A POTENTIAL SOURCE OF NEW VARIATION FOR RYE

摘要

High crossability of tetraploid triticale (X Triticasecah Wittmack) with 176 (Secale cereals 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 Radzikow contain small wheat translations, of both distal and intercalary type, into the rye 5R chromosome. The distal wheat translocationoccupying less than 5% of the long arm was transferred into diploid rye, but a disornic 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 x 2x rye hybrids to rye. Thousands of 2x rye plants and hundreds of lines were derived from numerous 4x triticale x 2x rye crosses. The lines with resistance to brown rust and powdery mildew were selected, as well as the lines with reduced content of anti-nutritive non-starch polysaccharides. No link between disease resistance and wheat DNA migration was proved, in spite of attempts. There exists a remarkable variation in crossability, hybrid sterility, homoeologous crossing-over frequency and in transmission of wheat chromosomesto rye. It makes a basis for selection of 4x triticale and rye materials with better suitability for chromosome engineeringin rye. The recurrent intergeneric crossing method was used for pre-breeding of such materials.