The present invention relates to plant genes involved in negative regulation of resistance to biotic and/or abiotic stress and uses thereof. More particularly, the present invention relates to plants comprising an inactivated MADS-box gene function, and having increased resistance to biotic and/or abiotic stress. The invention also relates to methods for producing modified plants having increased resistance to fungal, bacterial pathogens and/or to drought stress. In particular, the invention relates to methods for producing plants with inactivated MADS26 gene, or an ortholog thereof, and exhibiting resistance to biotic and/or abiotic stress.