Transfer of stem rust resistance to wheat from an Agropyron chromosome having a gametocidal effect

Abstract

Two procedures were used to induce homoeologous recombination between Agropyron elongatum (Host) Beauv. chromosome 7el2 and wheat chromosomes. One procedure involved the use of 'Chinese Spring' nullisomic 5B – tetrasomic 5D, and resulted in plants lacking chromosome 5B. In the second procedure, a line carrying the mutant gene ph1b was used, and plants were produced that had only a 5B chromosome carrying ph1b. Both procedures resulted in the transfer of a gene or genes for stem rust (Puccinia graminis tritici Eriks. and Henn.) resistance from chromosome 7el2 to wheat chromosomes. During the transfer process, it was discovered that both the whole Agropyron chromosome and the recombinant chromosomes showed preferential transmission through the female gametes, but not through the male gametes. On heterozygous plants seed set was greatly reduced. Apparently, the Agropyron chromosome or a gene carried by it had a gametocidal action that resulted in female gametes, which did not carry the gene, failing to function. However, homozygous lines showed normal fertility.