Genetic control of a novel series of trypsin inhibitors in wheat and its relatives.

The aneuploids of Chinese Spring wheat have been used to locate the genes (Ti-2) coding for a novel series of trypsin inhibitors to the long arms of the homoeologous group 5 chromosomes. Three allelic variants at the 5D locus were detected in a limited survey among wheat varieties, but no variation at the loci on either chromosome 5A or chromosome 5B was detected. Homoeoloci were found in a number of alien relatives, and in the majority of cases, these were present on the group 5 homoeologue. However, in Aegilops umbellulata, the Ti-U2 locus was located on a chromosome presumed to belong to homoeologous group 1. No Hordeum vulgare or H. chilense Ti-2 gene was expressed in a wheat background. This new marker will be especially useful as a screening mechanism for nullisomy of chromosome 5B in work aimed at introgression of alien chromatin into wheat.