Ehd1, a B-type response regulator in rice, confers short-day promotion of flowering and controls FT-like gene expression independently of Hd1
- Kazuyuki Doi1,5,6,
- Takeshi Izawa2,5,
- Takuichi Fuse2,3,
- Utako Yamanouchi4,
- Takahiko Kubo1,
- Zenpei Shimatani4,
- Masahiro Yano2, and
- Atsushi Yoshimura1
- 1Plant Breeding Laboratory, Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan; 2National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan; 3Bio-oriented Technology Research Advancement Institution, Toranomon 3-18-19-10F, Minato-ku, Tokyo 105-0001, Japan; 4Institute of Society for Techno-innovation of Agriculture, Forestry and Fisheries, Tsukuba, Ibaraki 305-0854, Japan
Abstract
Two evolutionarily distant plant species, rice (Oryza sativa L.), a short-day (SD) plant, and Arabidopsis thaliana, a long-day plant, share a conserved genetic network controlling photoperiodic flowering. The orthologous floral regulators—rice Heading date 1 (Hd1) and Arabidopsis CONSTANS (CO)—integrate circadian clock and external light signals into mRNA expression of the FLOWERING LOCUS T (FT) group floral inducer. Here, we report that the rice Early heading date 1 (Ehd1) gene, which confers SD promotion of flowering in the absence of a functional allele of Hd1, encodes a B-type response regulator that might not have an ortholog in the Arabidopsis genome. Ehd1 mRNA was induced by 1-wk SD treatment, and Ehd1 may promote flowering by inducing FT-like gene expression only under SD conditions. Microarray analysis further revealed a few MADS box genes downstream of Ehd1. Our results indicate that a novel two-component signaling cascade is integrated into the conserved pathway in the photoperiodic control of flowering in rice.
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Footnotes
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Supplemental material is available at http://www.genesdev.org.
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Article published online ahead of print. Article and publication date are at http://www.genesdev.org/cgi/doi/10.1101/gad.1189604.
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↵5 These two authors contributed equally to this work.
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↵6 Corresponding author.
↵6 E-MAIL kdoi{at}agr.kyushu-u.ac.jp; FAX 81-92-642-2822.
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- Accepted March 15, 2004.
- Received January 27, 2004.
- Cold Spring Harbor Laboratory Press