The effect of different doses of Ph1 on chromosome pairing in hybrids between tetraploid Agropyron elongatum and common wheat
Chromosome pairing at first meiotic metaphase was studied in F1 hybrids between tetraploid cytotypes of Agropyron elongatum and common wheat lines of the cultivar Chinese Spring, carrying zero, one, and two doses of Ph1. The bivalentization gene system of A. elongatum could not compensate for the absence of Ph1: hybrids deficient for this gene exhibited pairing between the Agropyron E1 and E2 chromosomes, between the wheat A, B, and D chromosomes, and between the Agropyron and the wheat chromosomes. In hybrids with one or two doses of Ph1, pairing was restricted to the Agropyron E1 and E2 chromosomes. It was concluded that E1 and E2 are distant homologues, thus further supporting the autoploidy nature of tetraploid A. elongatum. The genomic relationships in other polyploid species of the genus Agropyron is discussed in the light of this evidence.Key words: chromosome pairing, Triticum, common wheat, Agropyron.