Functional analyses of the flowering time geneOsMADS50, the putativeSUPPRESSOR OF OVEREXPRESSION OF CO 1/AGAMOUS‐LIKE 20(SOC1/AGL20) ortholog in rice

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Abstract
Summary: A late‐flowering mutant was isolated from rice T‐DNA‐tagging lines. T‐DNA had been integrated into the K‐box region ofOryza sativa MADS50(OsMADS50), which shares 50.6% amino acid identity with theArabidopsisMADS‐box geneSUPPRESSOR OF OVEREXPRESSION OF CO 1/AGAMOUS‐LIKE 20(SOC1/AGL20). While overexpression ofOsMADS50caused extremely early flowering at the callus stage,OsMADS50RNAi plants exhibited phenotypes of late flowering and an increase in the number of elongated internodes. This confirmed that the phenotypes observed in the knockout (KO) plants are because of the mutation inOsMADS50. RT‐PCR analyses of theOsMADS50KO and ubiquitin (ubi):OsMADS50plants showed thatOsMADS50is an upstream regulator ofOsMADS1,OsMADS14,OsMADS15,OsMADS18, andHd (Heading date)3a, but works either parallel with or downstream ofHd1andO. sativa GIGANTEA(OsGI). These results suggest thatOsMADS50is an important flowering activator that controls various floral regulators in rice.