title: Positional cloning and characterization reveal the molecular basis for soybean maturity locus E1 that regulates photoperiodic flowering.
abstract: The complex and coordinated regulation of flowering has high ecological and agricultural significance. The maturity locus E1 has a large impact on flowering time in soybean, but the molecular basis for the E1 locus is largely unknown. Through positional cloning, we delimited the E1 locus to a 17.4-kb region containing an intron-free gene (E1). The E1 protein contains a putative bipartite nuclear localization signal and a region distantly related to B3 domain. In the recessive allele, a nonsynonymous substitution occurred in the putative nuclear localization signal, leading to the loss of localization specificity of the E1 protein and earlier flowering. The early-flowering phenotype was consistently observed in three ethylmethanesulfonate-induced mutants and two natural mutations that harbored a premature stop codon or a deletion of the entire E1 gene. E1 expression was significantly suppressed under short-day conditions and showed a bimodal diurnal pattern under long-day conditions, suggesting its response to photoperiod and its dominant effect induced by long day length. When a functional E1 gene was transformed into the early-flowering cultivar Kariyutaka with low E1 expression, transgenic plants carrying exogenous E1 displayed late flowering. Furthermore, the transcript abundance of E1 was negatively correlated with that of GmFT2a and GmFT5a, homologues of FLOWERING LOCUS T that promote flowering. These findings demonstrated the key role of E1 in repressing flowering and delaying maturity in soybean. The molecular identification of the maturity locus E1 will contribute to our understanding of the molecular mechanisms by which a short-day plant regulates flowering time and maturity.
authors.affiliation: Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Harbin 150081, China. xiazhj@neigaehrb.ac.cn
authors.forename: Zhengjun
authors.initials: Z
authors.lastname: Xia
authors.forename: Satoshi
authors.initials: S
authors.lastname: Watanabe
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Yamada
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Tsubokura
authors.forename: Hiroko
authors.initials: H
authors.lastname: Nakashima
authors.forename: Hong
authors.initials: H
authors.lastname: Zhai
authors.forename: Toyoaki
authors.initials: T
authors.lastname: Anai
authors.forename: Shusei
authors.initials: S
authors.lastname: Sato
authors.forename: Toshimasa
authors.initials: T
authors.lastname: Yamazaki
authors.forename: Shixiang
authors.initials: S
authors.lastname: Lü
authors.forename: Hongyan
authors.initials: H
authors.lastname: Wu
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tabata
authors.forename: Kyuya
authors.initials: K
authors.lastname: Harada
mesh_terms: D001483:Base Sequence; D015139:Blotting, Southern; D002874:Chromosome Mapping; D022202:Chromosomes, Artificial, Bacterial / Q000235:genetics; D003001:Cloning, Molecular; D016000:Cluster Analysis; D017931:DNA Primers / Q000235:genetics; D005020:Ethyl Methanesulfonate; D035264:Flowers / Q000235:genetics / Q000502:physiology*; D018506:Gene Expression Regulation, Plant / Q000235:genetics*; D017343:Genes, Plant / Q000235:genetics*; D056426:Genetic Loci / Q000235:genetics*; D014644:Genetic Variation; D008957:Models, Genetic; D008969:Molecular Sequence Data; D016296:Mutagenesis; D017440:Photoperiod; D010802:Phylogeny; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D013025:Glycine max / Q000235:genetics* / Q000254:growth & development*
chemical_list: D017931:DNA Primers; D005020:Ethyl Methanesulfonate