The terminal step of fruit development in Arabidopsisinvolves valve separation from the replum, allowing seed dispersal. This process requires the activities of theSHATTERPROOF MADS-box genes, which promote dehiscence zone differentiation at the valve/replum boundary. Here we show that the FRUITFULL MADS-box gene, which is necessary for fruit valve differentiation, is a negative regulator ofSHATTERPROOF expression and that constitutive expression of FRUITFULL is sufficient to prevent formation of the dehiscence zone. Our studies suggest that ectopic expression ofFRUITFULL may directly allow the control of pod shatter in oilseed crops such as canola.