THE WHEAT WCS120 GENE FAMILY - A USEFUL MODEL TO UNDERSTAND THE MOLECULAR-GENETICS OF FREEZING TOLERANCE IN CEREALS

Winter, as compared with spring cereals, possess better acclimation me chanisms that allow them to overwinter and survive freezing temperatur es. This difference is genetically programmed and involves a complex g enetic system. To understand the nature of this system and its regulat ion by low temperature, genes associated with freezing tolerance in wh eat (Triticum aestivum L.) were identified and characterized. Among th ese, the wcs120 gene family encodes a group of proteins ranging in siz e from 12 to 200 kDa. As shown by biochemical, immunohistochemical, mo lecular and genetic analyses, this gene family is specific to the Poac eae, highly abundant and coordinately regulated by low temperature. Fu rthermore, accumulation of WCS protein is directly correlated with the development of freezing tolerance. These analyses also revealed a reg ulatory control of the vernalization process over low temperature gene expression in winter cereals. Recent studies suggest that the molecul ar mechanisms controlling the expression of these genes involve negati ve regulatory factors that are modulated by phosphorylation.