OsMADS51 is a short-day flowering promoter that functions upstream of Ehd1, OsMADS14, and Hd3a.
Although flowering regulatory mechanisms have been extensively studied in Arabidopsis (Arabidopsis thaliana), those in other species have not been well elucidated. Here, we investigated the role of OsMADS51, a type I MADS-box gene in the short-day (SD) promotion pathway in rice (Oryza sativa). In SDs OsMADS51 null mutants flowered 2 weeks later than normal, whereas in long days loss of OsMADS51 had little effect on flowering. Transcript levels of three flowering regulators-Ehd1, OsMADS14, and Hd3a-were decreased in these mutants, whereas those of OsGI and Hd1 were unchanged. Ectopic expression of OsMADS51 caused flowering to occur about 7 d earlier only in SDs. In ectopic expression lines, transcript levels of Ehd1, OsMADS14, and Hd3a were increased, but those of OsGI and Hd1 remained the same. These results indicate that OsMADS51 is a flowering promoter, particularly in SDs, and that this gene functions upstream of Ehd1, OsMADS14, and Hd3a. To further investigate the relationship with other flowering promoters, we generated transgenic plants in which expression of Ehd1 or OsGI was suppressed. In Ehd1 RNA interference plants, OsMADS51 expression was not affected, supporting our conclusion that the MADS-box gene functions upstream of Ehd1. However, in OsGI antisense plants, the OsMADS51 transcript level was reduced. In addition, the circadian expression pattern for this MADS-box gene was similar to that for OsGI. These results demonstrate that OsMADS51 functions downstream of OsGI. In summary, OsMADS51 is a novel flowering promoter that transmits a SD promotion signal from OsGI to Ehd1.
Kim
Song Lim
SL
Division of Molecular and Life Sciences and Biotechnology Research Center, Pohang University of Science and Technology, Pohang 790-784, Republic of Korea.
Lee
Shinyoung
S
Kim
Hyo Jung
HJ
Nam
Hong Gil
HG
An
Gynheung
G
D016375:Antisense Elements (Genetics); D001683:Biological Clocks / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology; D035264:Flowers / Q000502:physiology*; D015870:Gene Expression; D018507:Gene Expression Regulation, Developmental; D026161:MADS Domain Proteins / Q000378:metabolism / Q000502:physiology*; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D012275:Oryza / Q000502:physiology*; D017440:Photoperiod; D010940:Plant Proteins / Q000378:metabolism; D034622:RNA Interference
D016375:Antisense Elements (Genetics); D026161:MADS Domain Proteins; D010940:Plant Proteins