THE SUBSTITUTION OF A CHROMOSOME FROM AGROPYRON ELONGATUM FOR CHROMOSOMES OF HEXAPLOID WHEAT

Abstract

A set of 21 lines of wheat (Triticum aestivum L.) each monosomic for a different wheat chromosome and carrying an alien chromosome derived from Agropyron elongatum (Host.) Beauv (2n=70) was produced by crossing a disomic alien addition line to a set of wheat monosomics. The Agropyron chromosome carried moderate resistance to race 15B of Puccinia graminis var. tritici and this was used to identify plants carrying the chromosome. Attempts to obtain substitution of the wheat univalent by the Agropyron chromosome, by selfing the double monosomic (20" + 1[image] + 1[image] Agropyron) were successful only in the case of chromosomes of wheat homoeologous group S. The main barrier to production of substitution lines for chromosomes of other homoeologous groups was in the failure of alien substitution male gametes lacking chromosomes of groups other than 6. The results indicate a close, probably evolutionary, genetic relationship between the Agropyron chromosome and chromosomes of wheat homoeologous group 6.