Ectopic Expression of a WRKY Homolog from Glycine soja Alters Flowering Time in Arabidopsis
et al. (2013) Ectopic Expression of a WRKY Homolog from Glycine soja Alters Flowering Time in Arabidopsis.
PLoS ONE 8(8): e73295. doi:10.1371/journal.pone.0073295
Ectopic Expression of a WRKY Homolog from Glycine soja Alters Flowering Time in Arabidopsis
Xiao Luo 0
Xiaoli Sun 0
Baohui Liu 0
Dan Zhu 0
Xi Bai 0
Hua Cai 0
Wei Ji 0
Lei Cao 0
Jing Wu 0
Mingchao Wang 0
Xiaodong Ding 0
Yanming Zhu 0
Ji-Hong Liu, Key Laboratory of Horticultural Plant Biology (MOE), China
0 1 Plant Bioengineering Laboratory, Northeast Agricultural University , Harbin, Heilong Jiang , China , 2 Key Laboratory of Soybean Molecular Design Breeding, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences , Harbin, Heilong Jiang , China , 3 Department of Neurology, the University of Texas Southwestern Medical Center , Dallas, Texas , United States of America
Flowering is a critical event in the life cycle of plants; the WRKY-type transcription factors are reported to be involved in many developmental processes sunch as trichome development and epicuticular wax loading, but whether they are involved in flowering time regulation is still unknown. Within this study, we provide clear evidence that GsWRKY20, a member of WRKY gene family from wild soybean, is involved in controlling plant flowering time. Expression of GsWRKY20 was abundant in the shoot tips and inflorescence meristems of wild soybean. Phenotypic analysis showed that GsWRKY20 over-expression lines flowered earlier than the wild-type plants under all conditions: long-day and short-day photoperiods, vernalization, or exogenous GA3 application, indicating that GsWRKY20 may mainly be involved in an autonomous flowering pathway. Further analyses by qRT-PCR and microarray suggests that GsWRKY20 accelerating plant flowering might primarily be through the regulation of flowering-related genes (i.e., FLC, FT, SOC1 and CO) and floral meristem identity genes (i.e., AP1, SEP3, AP3, PI and AG). Our results provide the evidence demonstrating the effectiveness of manipulating GsWRKY20 for altering plant flowering time.
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Funding: This work was supported by the National Natural Science Foundation of China (31201223, 31171578); the Research Fund for the Doctoral
Program of Higher Education of China (20102325120002); the Key Project of the Ministry of National Education (212049). The funders had no role in study
design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
These authors contributed equally to this work.
In higher plants, a phase transition from vegetative to
reproductive development is one of the most important events
in their life history [1,2]. This transition is tightly coordinated
through a diverse array of signaling networks that integrate
various endogenous and exogenous signals [3]. Flowering time
is a key trait in adaptation, as it is vital for reproductive
success. Arabidopsis thaliana contains at least four flowering
pathways that are responsive to these cues: the photoperiod
pathway monitors changes in day length; the gibberellin
pathway plays a promotive role in flowering under
noninductive photoperiods; the vernalization pathway senses the
prolonged exposure to low temperature; and the autonomous
pathway mediates flowering by perceiving plant developmental
status [35]. Most recently, an endogenous pathway that adds
plant age to the control of flowering time has been described
[6]. Several genes, such as CONSTANS (CO), FLOWERING
LOCUS T (FT), SUPPRESSOR OF OVEREXPRESSION OF
CO 1 (SOC1), and FLOWERING LOCUS C (FLC) have been
identified as key components in these flowering signal
pathways [3]. CO, which encodes a zinc-finger transcriptional
activator, controls the timing of flowering by positively
regulating two floral integrators, FT [7] and SOC1 [8]; FLC, a
flowering repressor gene, also acts as an upstream regulator
gene of FT and SOC1 [9]. Moreover, these flowering
integrators have been shown to exhibit both overlapping and
independent functions in the determination of flowering time
and they integrate signals from multiple flowering pathways
and their expression levels eventually determine the exact
flowering time [3,10].
During the signaling of flowering regulation, a number of
transcription factors (TFs) are included. MADS-domain TF
family is one of the most important TF families that function in
flowering regulation. Among the floral transition genes, FLC,
SOC1, APETALA1 (AP1), APETALA3 (AP3), PISTILLAT (PI),
AGAMOUS (AG) and SEPALLATA3 (SEP3) are members of
the MADS-box gene family [11]. Furthermore, members of
other transcription factor families have been identified for their
role in the regulation of floral MADS-domain proteins and /or
other flowering time genes directly or indirectly [11], such as
NACs [12], MYBs [13], DREBs [14].
WRKY proteins are a class of DNA-binding transcriptional
factors which contain one or (...truncated)