DL acts in whorl 4 to specify carpel identity in conjunction with other genes including class C genes. Loss of DL function results in the spatial expansion of SPW1 function in whorl 4, which leads to the transformation of the gynoecium into stamens. Likewise, the loss of SPW1 function causes spatial expansion of DL function in whorl 3, which leads to the transformation of stamens into carpels. The loss of both SPW1 and DL causes the transformation of whorl 3 and 4 organs into indeterminate structures that produce organs with no apparent identity. Such mutually antagonistic interaction of DL and SPW1 play an essential role in specifying floral organ identity.