The Sacchavomyces cerevisiae strain WYT, deficient in the YAP1 transcription factor, was used in a molecular screen to identify genes from Arabidopsis thaliana that could overcome the oxidative stress-sensitive phenotype of these yeast cells, A cDNA named CEO1 increased the tolerance to oxidative damage caused by tert-butylhydroperoxide of both the Yap1(-) mutant and the wild-type yeast, Additionally, in Yap1(-) yeast, CEO1 also induced cross-tolerance to oxidative damage caused by hydrogen peroxide and diamide, CEO1,was assigned as being part of a small gene family that, until now, is exclusively, restricted to plants, In Arabidopsis, CEO1 was produced in all organs, especially in roots and stems. By using the yeast two-hybrid system, proteins that specifically interact with CEO1 in yeast mere identified, and putative DNA-binding proteins were consistently recovered, (C) 2000 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved .