A DURUM WHEAT DISOMIC-SUBSTITUTION LINE HAVING A PAIR OF CHROMOSOMES FROMTRITICUM BOEOTICUM: EFFECT ON GERMINATION AND GROWTH

Abstract

Durum wheat selection 56-1 was crossed with an accession of T. boeoticum Boiss.; and a F2 plant had 13 pairs plus 2 univalents (13" + 2'') at metaphase I. In subsequent generations, plants with the chromosome configuration 14" + 1'' were selected. Plants with 14" + 1'' produced 2 types of seed. Approximately 78% of the seeds had purple pericarp and the rest were amber. Purple seeds failed to germinate unless they were soaked overnight in a 1 mg/l solution of gibberellic acid (GA3). The seeds with purple pericarp had 28 chromosomes including a pair of T. boeoticum chromosomes which were substituted for a pair of 4B chromosomes from durum wheat. The disomic-substitution plants were dwarfs and male-sterile. Amber seeds had the chromosome constitution 13" + X" + 4B'' (X = the T. boeoticum chromosome) and produced male-fertile, normal height plants. Chromosome pairing relationships indicated that the T. boeoticum chromosome had no more homology with wheat chromosomes 4A, 4B and 4D than they had with each other. The T. boeoticum chromosome compensated for the loss of durum chromosome 4B except for a locus affecting GA.