Ehd1, a B-type response regulator in rice, confers short-day promotion of flowering and controls FT-like gene expression independently of Hd1.
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.
Doi
Kazuyuki
K
Plant Breeding Laboratory, Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan. kdoi@agr.kyushu-u.ac.jp
Izawa
Takeshi
T
Fuse
Takuichi
T
Yamanouchi
Utako
U
Kubo
Takahiko
T
Shimatani
Zenpei
Z
Yano
Masahiro
M
Yoshimura
Atsushi
A
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
D029681:Arabidopsis Proteins; C418905:FT protein, Arabidopsis; C484391:Hd1 protein, Arabidopsis; D011506:Proteins; D006655:Histone Deacetylases