The inheritance in wheat of crossability with rye

Abstract

1. By the use of intervarietal chromosome substitution lines, the poor crossability with rye ( S. cereale , 2 n = 14) of the wheat ( T. aestivum , 2 n = 42) variety Hope was shown to be determined by chromosomes 5A and 5B. The genes Kr 1 and Kr 2 , which are responsbile for poor crossability (Lein, 1943), are probably located on chromosomes 5B and 5A respectively. 2. Crossability is actively inhibited by the dominant alleles, Kr 1 and Kr 2 , of Hope and is apparently not enhanced by the recessive alleles, kr 1 and kr 2 , of the readily crossable variety Chinese Spring. 3. The inhibition of crossability with rye conferred evolutionary and agricultural advantage upon wheat by preventing the production of sterile wheat-rye hybrids which could be regarded as weeds generated from within the crop.