Proposed model to illustrate the genetic interaction between OsMADS3, OsMADS13, and DL in rice flower development. A, Interactions between rice floral organ homeotic genes of A-function genes (such as OsMADS15), SPW1, OsMADS3, OsMADS13, and DL. Different colors represent the expression patterns of genes in lodicules, stamens, the carpel, and the ovule. OsMADS3 possibly represses the expression of A-function genes such as OsMADS15 in the inner floral organs; DL may antagonize the expression of SPW1 and OsMADS15. While OsMADS13 may indirectly limit the expression of DL in the ovule, DL may directly or indirectly positively regulate OsMADS13 expression. The broken arrow indicates the possibly indirect or direct regulation of the OsMADS13 expression by DL. B, Functions of OsMADS3, DL, and OsMADS13 in specifying floral organ identities and floral meristem termination. Green lines and red arrows indicate the functions of repression and promotion, respectively. OsMADS3 regulates the number of lodicules in whorl 2 by suppressing lodicule development, particularly near the palea (Yamaguchi et al., 2006), represses the formation of lodicules and determines the stamen identity in whorl 3, and specifies ovule identity in the floral center. DL represses the formation of stamens and specifies the carpel identity in the flower center, while OsMADS13 represses carpel formation and determines ovule identity. OsMADS13 may terminate floral meristem termination in parallel with OsMADS3, and DL may regulate the floral meristem determinacy in the same pathway of OsMADS13. OsMADS3 and DL can redundantly terminate the floral meristem.