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Nat Genet. 2010 Jul;42(7):635-8. doi: 10.1038/ng.606. Epub 2010 Jun 13.

A pair of floral regulators sets critical day length for Hd3a florigen expression in rice.

Author information

1
Photosynthesis and Photobiology Research Unit, National Institute of Agrobiological Sciences, Tsukuba, Japan.

Abstract

The critical day length triggering photoperiodic flowering is set as an acute, accurate threshold in many short-day plants, including rice. Here, we show that, unlike the Arabidopsis florigen gene FT, the rice florigen gene Hd3a (Heading date 3a) is toggled by only a 30-min day-length reduction. Hd3a expression is induced by Ehd1 (Early heading date 1) expression when blue light coincides with the morning phase set by OsGIGANTEA(OsGI)-dependent circadian clocks. Ehd1 expression is repressed by both night breaks under short-day conditions and morning light signals under long-day conditions. Ghd7 (Grain number, plant height and heading date 7) was acutely induced when phytochrome signals coincided with a photosensitive phase set differently by distinct photoperiods and this induction repressed Ehd1 the next morning. Thus, two distinct gating mechanisms--of the floral promoter Ehd1 and the floral repressor Ghd7--could enable manipulation of slight differences in day length to control Hd3a transcription with a critical day-length threshold.

PMID:
20543848
DOI:
10.1038/ng.606
[Indexed for MEDLINE]

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