Interactions between the scs and Vi genes in alloplasmic durum wheat

Two nuclear genes, vitality (Vi) on an A- or B-genome chromosome and species cytoplasm specific (scs) on a 1DL telosome from Triticum aestivum L. or a telosome from Aegilops uniaristata Vis. (un telosome), improved compatibility between the nucleus of Triticum turgidum L. var. durum and the cytoplasm of Ae. longissima S. &M. or Ae. uniaristata. To study interactions between Vi and scs and to determine the chromosomal location of Vi, 29-chromosome fertile plants were crossed with 13 D-genome disomic-substitution (d-sub) lines [except 5D(5A)] of 'Langdon' durum. F1 and backcross progenies were examined for meiotic chromosome number and pairing, fertility, and plant vigor. In 11 crosses, Vi restored seed viability but produced double-monosomics (d-monos) with greatly reduced growth and vigor. In contrast, crosses involving 1D(1A) and 1D(1B) d-sub lines produced d-monos with normal vigor and anthesis but nonfunctional pollen. A backcross of 1D + 1A d-mono F1 and 1D(1A) d-sub lines produced 11 male steriles; 3 had 13 II + 1 II 1D + 1 I 1A, 2 had 13 II + 2 I, 1 had 13 II + 1 II 1D(1A), and 5 were not examined. Crosses of 1D + 1A d-mono F1 with control durum, lo durum (with 1DL), and un durum (with un telosome) lines produced 16 male-sterile d-monos and 14 fertiles with 14 II + 1 I 1D, showing that 15-chromosome female gametes transmitted monosomes 1A and 1D. However, BC2F1's from 1D + 1B d-mono x fertile line with un telosome included 20 male-sterile d-monos, 6 fertile triple monosomics (13 II + 1 I 1D + 1 I 1B + t I un telosome), and 1 fertile plant with a 1B/1D translocation. Unlike d-mono 1A + 1D, d-mono 1B + 1D did not transmit 15-chromosome female gametes with monosomes 1D and 1B. Additional backcrosses also indicated that homozygous scs caused male sterility in 1D(1A) and 1D(1B) d-subs and that the procedure used was not suitable for the chromosomal location of Vi.