SOME FACTORS IN THE DIFFERENT CHROMOSOME SETS OF COMMON WHEAT

Abstract

In crosses between 21-chromosome (vulgare) and 14-chromosome (emmer) wheats many hybrid lines which had only 14 pairs of chromosomes were identified and were then studied from the standpoint of their emmer and vulgare characters. Any vulgare character which appears in such lines must be determined by genes in the primary set of 14 chromosomes which mate in F₁ with those of emmer. Vulgare characters not appearing in such lines are determined by genes in the secondary set of 7 which remain unmated in F₁. In this way it has been determined that 7 of the 19 characters studied in durum crosses and 9 of the 21 studied in dicoccum crosses are determined by genes in the primary set of 14 (for list see Table II). For several other vulgare characters it has been shown that necessary genes are in both the primary 14 and the secondary 7 (Table III). There is little to indicate that genes determining important species-distinguishing characters are concentrated in the secondary set of 7, as is implied in the theory that vulgare wheat has resulted from the crossing of an emmer with Aegilops and that the set of 7 is derived from Aegilops and homologous with a set in that genus. Evidence in regard to the mode of inheritance of certain characters is given.