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 (C) 2010 Elsevier Inc All rights reserved