CHROMOSOME MAPPING OF LOW-TEMPERATURE INDUCED WCS120 FAMILY GENES ANDREGULATION OF COLD-TOLERANCE EXPRESSION IN WHEAT

Low-temperature (LT) induced genes of the Wcs120 family in wheat (Trit icum aestivum) were mapped to specific chromosome arms using Western a nd Southern blot analysis on the ditelocentric series in the cultivar Chinese Spring (CS). Identified genes were located on the long arms of the homoeologous group 6 chromosomes of all 3 genomes (A, B, and D) o f hexaploid wheat. Related species carrying either the A, D, or AB gen omes were also examined using Southern and Western analysis with the W cs120 probe and the WCS120 antibody. All closely related species carry ing one or more of the genomes of hexaploid wheat produced a 50 kDa pr otein that was identified by the antibody, and a Wcs120 homoeologue wa s detected by Southern analysis in all species, In the absence of chro mosome arm 6DL in hexaploid CS wheat no 50 kDa protein was produced an d the high-intensity Wcs120 band was missing, indicating 6DL as the lo cation of Wcs120 but suggesting silencing of the Wcs120 homoeologue in the A genome. Levels of proteins that cross-reacted with the Wcs120 a ntibody and degrees of cold tolerance were also investigated in the Ch inese Spring/Cheyenne (CS/CNN) chromosome substitution series. CNN chr omosome 5A increased the cold tolerance of CS wheat, Densitometry scan ning of Western blots to determine protein levels showed that the grou p 5 chromosome 5A had a regulatory effect on the expression of the Wcs 120 gene family located on the group 6 chromosomes of all three hexapl oid wheat genomes.