| Cytological studies of hybrids involving Triticum
durum and Secale cereale Kiyoshi SAKANAGA Laboratory of Genetics and Plant Breeding, Univ. of Alberta, Edmonton, Alberta, Canada Hybrids were secured from crosses between Triticale, the allopolyploid of T. durum variety Carleton and Secale cereale, and the durum varieties Iumillo, F.P.I. 94587 and Stewart, and spring rye. At MI, PMC's with 14II+7I were observed most frequently in the hybrids between Triticale and the durum varieties F.P.I. 94587 and Stewart. Hybrids with 31 and 32 somatic chromosomes were derived from a cross between Triticale and Iumillo. The high frequency of PMC's with 14 bivalents indicated that these hybrids probably originated from the fertilization of a Triticale egg of ABS-3 or ABS-4 constitution by a gemete of the AB constitution of tetraploid wheat. Quadrivalents usually in the form of a ring of four chromosomes were observed in all hybrids involving durum varieties. The frequency of microsporocytes with quadrivalents in the hybrids involving Iumillo ranged from 19.0 to 37.1%. Self and backcross progenies of the hybrids segregated into ring forming and normal plants, which indicated the presence of a reciprocal translocation between the wheat chromosomes. Six hybrids, two with 27, three with 26 and one with 25 somatic chromosomes were obtained from a cross between Triticale and spring rye. Phenotypically, the 27 chromosome hybrids showed the hairy-neck characteristic of both parents; the others were characterized by non-pubescence of the peduncle. Pollen mother cells with 5 bivalents were observed most frequently at MI in the non-hairy neck plants. One of the 27 chromosome plants had a mode of 3 bivalents at MI while the other had a mode of 6 bivalents. Approximately 38 percent of the PMC's in the latter plant had trivalents. A 29 chromosome plant monosomic for chromosome I of rye was derived from a backcross of the hybrid between Triticale and F.P.I. 94587 to Khapli. The presence of the rye chromosome adversely affected plant height and increased the frequency of asynapsis of one or two pairs of wheat chromosomes. |