title: Ehd1, a B-type response regulator in rice, confers short-day promotion of flowering and controls FT-like gene expression independently of Hd1.
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.
authors.affiliation: Plant Breeding Laboratory, Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan. kdoi@agr.kyushu-u.ac.jp
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Doi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Izawa
authors.forename: Takuichi
authors.initials: T
authors.lastname: Fuse
authors.forename: Utako
authors.initials: U
authors.lastname: Yamanouchi
authors.forename: Takahiko
authors.initials: T
authors.lastname: Kubo
authors.forename: Zenpei
authors.initials: Z
authors.lastname: Shimatani
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yano
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yoshimura
mesh_terms: D000595:Amino Acid Sequence; D029681:Arabidopsis Proteins / Q000235:genetics; D035263:Flowering Tops / Q000235:genetics / Q000378:metabolism*; D006655:Histone Deacetylases; D008969:Molecular Sequence Data; D012275:Oryza / Q000235:genetics / Q000378:metabolism*; D017440:Photoperiod; D010802:Phylogeny; D011506:Proteins / Q000378:metabolism*; D040641:Quantitative Trait Loci
chemical_list: D029681:Arabidopsis Proteins; C418905:FT protein, Arabidopsis; C484391:Hd1 protein, Arabidopsis; D011506:Proteins; D006655:Histone Deacetylases