Premium
Ehd3 , encoding a plant homeodomain finger‐containing protein, is a critical promoter of rice flowering
Author(s) -
Matsubara Kazuki,
Yamanouchi Utako,
oue Yasunori,
Sugimoto Kazuhiko,
Wang ZiXuan,
Minobe Yuzo,
Yano Masahiro
Publication year - 2011
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2011.04517.x
Subject(s) - biology , genetics , gene , oryza sativa , mutant , arabidopsis , repressor , homeobox , promoter , transcription factor , gene expression
Summary Oryza sativa (rice) flowers in response to photoperiod, and is a facultative short‐day (SD) plant. Under SD conditions, flowering is promoted through the activation of FT‐like genes (rice florigens) by Heading date 1 ( Hd1 , a rice CONSTANS homolog) and Early heading date 1 ( Ehd1 , with no ortholog in the Arabidopsis genome). On the other hand, under long‐day (LD) conditions, flowering is delayed by the repressive function of Hd1 on FT‐like genes and by downregulation of Ehd1 by the flowering repressor Ghd7 – a unique pathway in rice. We report here that an early heading date 3 ( ehd3 ) mutant flowered later than wild‐type plants, particularly under LD conditions, regardless of the Hd1‐ deficient background . Map‐based cloning revealed that Ehd3 encodes a nuclear protein that contains a putative transcriptional regulator with two plant homeodomain (PHD) finger motifs. To identify the role of Ehd3 within the gene regulatory network for rice flowering, we compared the transcript levels of genes related to rice flowering in wild‐type plants and ehd3 mutants. Increased transcription of Ghd7 under LD conditions and reduced transcription of downstream Ehd1 and FT ‐ like genes in the ehd3 mutants suggested that Ehd3 normally functions as an LD downregulator of Ghd7 in floral induction. Furthermore, Ehd3 ghd7 plants flowered earlier and show higher Ehd1 transcript levels than ehd3 ghd7 plants, suggesting a Ghd7 ‐independent role of Ehd3 in the upregulation of Ehd1 . Our results demonstrate that the PHD‐finger gene Ehd3 acts as a promoter in the unique genetic pathway responsible for photoperiodic flowering in rice .