Abstract
A derivative of Triticum aestivum L. emend Thell. cultivar Rescue3 (2n = 42) × Agropyron elongatum (Host.) Beauv. (2n = 70) is immune to wheat streak mosaic virus Marmor virgatum McK., has 21 pairs of chromosomes, and hybridizes readily with wheat. By crossing with lines ditelosomic for known chromosomes it was determined that Agropyron chromosomes have replaced wheat chromosomes 4D, 5D, and 6D. In growth habit the immune line is like Rescue, but its long slender spikes, absence of awns, and small, slender, blue seeds resemble Agropyron.