Rice ternary MADS protein complexes containing class B MADS heterodimer

Abstract

To investigate ternary MADS protein complexes involved in the regulation of floral organ development in rice, we identified MADS proteins interacting with the class B MADS heterodimers, OsMADS16–OsMADS4 and OsMADS16–OsMADS2, using yeast three-hybrid assay. The class B heterodimers interacted with OsMADS6, 7, 8, 14 and 17, which belong to AP1-like, SEP-like or AGL6-like MADS proteins, generating ternary complexes. The entire region of the K and C domains of OsMADS4 was required for the formation of the OsMADS16–OsMADS4–OsMADS6 and OsMADS16–OsMADS4–OsMADS7 ternary complexes. Analysis results of transgenic plants concomitantly suppressing OsMADS4 and OsMADS6, together with the results of previous studies, suggest that the OsMADS16–OsMADS4–OsMADS6 ternary complex plays an important role in floral development, especially lodicule development.