Genetic control of the long glume phenotype in tetraploid wheat by homoeologous chromosomes

The Ispahan emmer wheat, Triticum ispahanicum Heslot, was discovered in Iran 1957 by the French expedition of Vinnot-Bourgen. T. ispahanicum has a long glume and a more slender spike than I turgidum var. polonicum. The objectives of this study were (1) to determine the inheritance and chromosomal location of the gene for long glume, P-2, from T. ispahanicum using the near-isogenic line P-2-LD222, and (2) to compare the effects of the genes for long glume. The gene for long glume, P-2, was located approximately 36.5 cM from the cn-B1 locus, which controls the chlorina trait and approximately 40 cM from the centromere on the long arm of 7B. The location of PZ approximately 29.6 cM from the Pc locus produced additional evidence that the order of loci was cn-BI, Pt, and Pc. This raises the possibility of a paralogous gene set conditioning long glumes. A significant deviation from a 3:1 ratio in the F-2 of LDN 7D(7B)/P-2-LD222 confirmed the location of P-2 on chromosome 7B. It is proposed that T. ispahanicum originated as a mutation of a gene affecting glume length on chromosome 7B of T. dicoccum, a spelt type of cultivated tetraploid wheat.