The present invention relates to isolated nucleic acid molecules and their corresponding encoded polypeptides able confer the trait of improved plant size, vegetative growth, growth rate, seedling vigor and/or biomass in plants challenged with saline and/or oxidative stress conditions. The present invention further relates to the use of these nucleic acid molecules and polypeptides in making transgenic plants, plant cells, plant materials or seeds of a plant having plant size, vegetative growth, growth rate, seedling vigor and/or biomass that are improved in saline and/or oxidative stress conditions with respect to wild-type plants grown under similar conditions.