OsCO3, a CONSTANS-LIKE gene, controls flowering by negatively regulating the expression of FT-like genes under SD conditions in rice.
The photoperiod is an important environmental stress that determines flowering time. The CONSTANS (CO) and Heading date 1 (Hd1) genes are known to be central integrators of the photoperiod pathway in Arabidopsis and rice, respectively. Although they are both members of the CONSTANS-LIKE (COL) family and have two B-boxes and a CCT domain, rice also possesses novel COL genes that are not found in Arabidopsis. Here, we demonstrate that a novel COL gene, OsCO3, containing a single B-box and a CCT domain, modulates photoperiodic flowering in rice. The circadian expression pattern of OsCO3 mRNA oscillated in a different phase from Hd1 and was similar to that of OsCO3 pre-mRNA, suggesting that the diurnal expression pattern of OsCO3 transcripts may be regulated at the transcriptional level. Overexpression of OsCO3 specifically caused late flowering under short day (SD) conditions relative to wild-type rice plants. The expression of Hd3a and FTL decreased in these transgenic plants, whereas the expression of Hd1, Early heading date 1 (Ehd1), OsMADS51, and OsMADS50 did not significantly change. Our results suggest that OsCO3 primarily controls flowering time under SD conditions by negatively regulating Hd3a and FTL expression, independent of the SD-promotion pathway.
Kim
Soon-Kap
SK
Plant Signaling Network Research Center, School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, South Korea.
Yun
Choong-Hyo
CH
Lee
Jeong Hwan
JH
Jang
Yun Hee
YH
Park
Hyo-Young
HY
Kim
Jeong-Kook
JK
D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D002940:Circadian Rhythm; D035264:Flowers / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D007438:Introns; D026161:MADS Domain Proteins / Q000378:metabolism; D012275:Oryza / Q000235:genetics* / Q000502:physiology; D017440:Photoperiod; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000378:metabolism
D026161:MADS Domain Proteins; D010940:Plant Proteins