Functional Analysis Of OsMADS34 In The Development Of Inflorescence Architecture And Glume In Rice (Oryza Sativa L.)

The rice inflorescence architecture plays an important role in the productivity of grains. Whether the empty glume of rice spikelete came from leaf or rudimentary spikelete still remains less understood. Here we have isolated a recessive mutatant, named osmadsS34, which has abnormal inflorescence architecture and empty glume development. In the wild-type inflorescence, the number of primary branch is around 10-12, and finally formed about 194 spikeletes in one panicle. In osmads34, however, the main-axis meristem produced about 17 branch primordia, and the spikelet number in one panicle was reduced to 133, suggesting OsMADS34 is critical for controlling the inflorescence development in rice. In addition, the osmads34 spikeletes had normal floral organs, while the glumes seemed abnormal. The average length of wild type empty glumes was about 2mm in length, and the mutant empty glume was about 9.25mm. Section results showed that the mutant empty glume seemed to be transformed into lemma-like structure, suggesting that OsMADS34 controls the development of empty glume during rice spikelete development. Our previous data indicated that this mutation was from one unique monocot MADS-box gene, OsMADS34, this was also confirmed by complementary test. The localization of the OsMADS34-GFP fusion protein in the nucleus suggests that OsMADS34 possibly functions as a transcription factors. Expression pattern analysis showed that OsMADS34 is expressed in root, shoot, leaf and the organs of spikelete (glumes, lemma, palea, lodicules, stamen and carple). Yeast-two-hybrid analysis shows that OsMADS34 can interact with itself, suggesting that OsMADS34 may act as homodimers in vivo. Moreover, the fon4/osmads34 double mutant has more primary branchs and less spikeletes, indicating that FON4 and OsMADS34 work together during the development of the inflorescence. These results indicate that OsMADS34 is a key component in the development of inflorescence architecture and empty glume in rice.