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In order to get comparable information on locations of genes in Emmer wheat (genome formula: AABB) and Aegilops squarrosa (DD) with those in common wheat (AABBDD), monosomic analysis of four synthesized 6x wheats was carried out using the monosomic series of Chinese Spring. The characters studied were growth habit, awnedness, glume hairiness and waxiness. The following results were obtained. (1) Growth habit. Genes belonging to three allelic series, Sg1, Sg2 and Sg3 mainly control growth habit of the synthetics. Two alleles, Sg1c and sg1, which are derived from different Ae. squarrosa strains, have been identified at the Sg1 locus. Three alleles, Sg2, Sg2c and sg2, at the Sg2 locus and two alleles, Sg3 and sg3, at the Sg3 locus have been found in different Emmer species. (2) Awnedness. All the synthetics and, accordingly, their respective Emmer components carry only hd and b2 alleles. None of the four synthetics have any major inhibitor, Hd, B1 or B2. (3) Glume hairiness. Glume hairiness of ABD-4 is controlled by a single dominant gene that is derived from T. durum Golden Ball. This gene is homologous to the Hg allele of common wheat. (4) Waxiness. Waxiness of the synthesized hexaploids is controlled by genes belonging to three allelic series, W, I1-W and I2-W. Both inhibitors, I1-W and I2-W are epistatic to a promotor, W. The alleles W and w at the W locus and I1-W and i1-W at the I1-W locus are found in Emmer components, while the inhibitor I2-W is present in Ae. squarrosa; the latter seems to have been lost at or after the synthesis of ABD-2. These results indicate that most of the alleles known in the present-day common wheat were also present in its ancestors, Emmer wheat or Ae. squarrosa. One of the contributions of Ae. squarrosa to the evolution of common wheat seems to be the donation of the most effective winter habit gene, sg1.

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