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| − | '''''SALT-RESPONSIVE ERF1 (SERF1)''''' is a rice (''Oryza sativa'') transcription factor ('''TF''') gene<ref name="ref1"/>.
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| | ==Annotated Information== | | ==Annotated Information== |
| | ===Function=== | | ===Function=== |
| − | *Loss of ''SERF1'' impairs the salt-inducible expression of genes encoding members of a mitogen-activated protein kinase('''''MAPK''''') cascade and salt tolerance–mediating TFs. '''SERF1-dependent genes''' are '''H<sub>2</sub>O<sub>2</sub> responsive''' and demonstrate that '''SERF1 binds to the promoters''' of ''MAPK KINASE KINASE6 ('''MAP3K6''')'', '''''MAPK5''''', ''DEHYDRATION-RESPONSIVE ELEMENT BINDING2A ('''DREB2A''')'', and ''ZINC FINGER PROTEIN179 ('''ZFP179''')'' in vitro and in vivo(Figure 2)<ref name="ref1"/>.
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| − | *SERF1 also '''directly induces''' its own gene expression. In addition, ''SERF1'' is '''a phosphorylation target of MAPK5''', resulting in '''enhanced transcriptional activity''' of ''SERF1'' toward its direct target genes. In agreement, plants deficient for ''SERF1'' are '''more sensitive''' to salt stress compared with the wild type, while constitutive overexpression of SERF1 '''improves salinity tolerance'''. ''SERF1'' amplifies the '''reactive oxygen species–activated MAPK cascade signal''' during the '''initial phase''' of salt stress and translates the '''salt-induced signal''' into an appropriate expressional response resulting in salt tolerance<ref name="ref1"/>.
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| − | *''SERF1'' is a '''positive regulator''' of '''short-Term and long-term salt stress tolerance'''<ref name="ref1"/><ref name="ref2"/>. Overexpression of ''SERF1'' '''increases oxidative stress tolerance'''. Phosphorylation of SERF1 increases its ability to activate transcription of target genes. ''SERF1'' is a '''phosphorylation target of MAPK5'''<ref name="ref1"/>.
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| − | *Metabolic profiling and expression analysis show that the action of SERF1 in '''signal communication''' to the '''shoot''' is '''independent from ABA''', but does '''affect''' the '''accumulation of ROS-related metabolites''' and '''transcripts''' under short-term salt stress<ref name="ref2"/>.
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| − | *''SERF1'' '''suppresses grain filling and germination''' by '''repressing''' the expression of the RICE PROLAMN BOX-BINDING FACTOR('''RPBF''') gene and modulating starch metabolism<ref name="ref3"/>.
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| − | *''SERF1'' directly regulates RICE PROLAMIN-BOX BINDING FACTOR (''RPBF''), a TF that functions as a '''positive regulator of grain filling'''. Loss of SERF1 enhances RPBF expression resulting in larger grains with increased starch content, while SERF1 overexpression represses RPBF resulting in smaller grains<ref name="ref3"/>.
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| − | *Consistently, during 10 grain filling, starch biosynthesis genes such as GRANULE-BOUND STARCH 11 SYNTHASEI (GBSSI), STARCH SYNTHASEI (SSI), SSIIIa and ADP-GLUCOSE 12 PYROPHOSPHORYLASE LARGE SUBUNIT2 (AGPL2) are upregulated in SERF1 knock-out grains. Moreover, ''SERF1'' is '''a direct upstream regulator of GBSSI'''. In addition, SERF1 negatively regulates germination by controlling RPBF expression, which mediates the gibberellic acid (GA)-induced expression of RICE AMYLASE1A (RAmy1A). Loss of SERF1 results in more rapid seedling establishment, while SERF1 overexpression has the opposite effect. Our study reveals that SERF1 18 represents a negative regulator of grain filling and seedling establishment by timing the expression of RPBF<ref name="ref3"/>.
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| − | '''GO assignment(s):''' [http://amigo.geneontology.org/amigo/term/GO:0006814 GO:0006814], [http://amigo.geneontology.org/amigo/term/GO:0006885 GO:0006885], [http://amigo.geneontology.org/amigo/term/GO:0015299 GO:0015299], [http://amigo.geneontology.org/amigo/term/GO:0015385 GO:0015385], [http://amigo.geneontology.org/amigo/term/GO:0016021 GO:0016021]
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| − | ===Mutation===
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| − | *A homozygous T-DNA '''knockout line'''<ref name="ref1"/>:
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| − | **''serf1''
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| − | **The absence of full-length SERF1 transcript in homozygous ''serf1'' plants was confirmed by quantitative RT-PCR (qRT-PCR).
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| − | *Three independent transgenic lines<ref name="ref1"/>:
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| − | **KD 3-1
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| − | **KD 4-1
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| − | **KD 5-1
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| − | **After application of salt (200 mM NaCl), the '''leaf temperature increased''' in all lines. However, from 15 min onwards, ''serf1'' and the ''SERF1'' knockdown lines KD 4-1 and KD 5-1 '''exhibited higher leaf temperature''' compared with control lines, which suggesting that '''loss or knockdown''' of SERF1 '''decreases''' the tolerance to '''osmotic stress''' induced by salt treatment.
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| − | **By contrast, SERF1 overexpression lines showed '''lower leaf temperatures''' after 25 min of salt stress compared with the empty vector (EV) line.
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| − | **Leaf temperature of mock-treated ''serf1'' plants did not differ from the wild type; likewise, ''SERF1'' knockdown and overexpression plants and their respective controls showed similar leaf temperatures under control conditions.
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| − | *The rapid decline in sugars might be symptomatic to the salt sensitivity of serf1, as sugars not only act in energy metabolism but also function as osmoprotectants<ref name="ref2"/>.
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| | ===Expression=== | | ===Expression=== |
| − | [[File: SERF1 expression1.jpg|right|thumb|200px|'''Figure 1.''' ''SERF1 Is Specifically Induced by Salt Stress and H<sub>2</sub>O<sub>2</sub> Treatment and Is Expressed in the Vascular Tissues of Roots and Leaves.(from reference <ref name="ref1"/>).'']]
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| − | *''SERF1'' expression is induced within 10 min of '''salt stress''' and reaches maximal expression after 60 min of treatment.
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| − | *''Schmidt et al.'' tested the expressional response of ''SERF1'' in wild-type roots and leaves upon H<sub>2</sub>O<sub>2</sub>, ABA, or mannitol application (Figure 1A). Application of of '''ABA or mannitol''' did '''not affect''' the expression of ''SERF1''.
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| − | By contrast, as observed for salt stress, '''H<sub>2</sub>O<sub>2</sub>''' treatment caused an upregulation of SERF1 within 30 min exclusively in '''roots''', albeit an induction was also observed after 3 h of treatment. Rice plants expressing a b-glucuronidase (GUS) reporter gene fused to a 1-kb promoter of SERF1 exhibited GUS activity in the vascular cylinder of the root and the main and commissural veins of '''leaves'''(Figure 1B).
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| − | *Also, '''decreased expression''' of SERF1 in knockdown lines resulted in a '''stronger reduction''' of '''chlorophyll''' after MV and H<sub>2</sub>O<sub>2</sub> treatment compared with the EV line. By contrast, leaves of plants overexpressing SERF1 showed '''higher levels''' of '''chlorophyll''' after either MV or H<sub>2</sub>O<sub>2</sub> treatment compared with EV leaves. Thus, ''SERF1'' is a positive regulator of oxidative stress tolerance. ''SERF1'' overexpression lines showed enhanced expression of ''DREB2A'', ''AP37'', ''ZFP179'', ''ZFP182'', ''ZFP252'', ''SNAC1'', ''SNAC2'', and ''NAC5'' under control conditions<ref name="ref1"/>.
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| − | ===Localization===
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| − | Although ''SERF1'' does not contain a known nuclear localization signal, stable transformation of rice plants with a construct encoding a CFP-tagged version of ''SERF1'' revealed '''nuclear localization of SERF1 in leaf epidermal cells''' (Figure 1C)<ref name="ref1"/>.
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| | ===Evolution=== | | ===Evolution=== |
| − | *The rice genome encodes '''15 group II ERF genes''' of the '''DREB subfamily''', which can be '''subdivided''' into '''three classes'''. SERF1 '''belongs to group IIc ERFs''', which lack both the EAR motif and CMII-3 motif found in members of the '''groups IIa and IIb '''<ref name="ref4"/>.
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| − | *The corresponding proteins share a highly conserved AP2 DNA binding domain, the '''C terminus''' of SERF1 '''bears two conserved predicted helical structures'''(H1 and H2), of which the latter is only found in monocots. One of the two SERF1 homologs in ''Arabidopsis'' is a potential MAPK phosphorylation target<ref name="ref5"/>, suggesting that SERF1 might represent a target of a rice MAPK cascade<ref name="ref1"/>.
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| − | ===Knowledge Extension=== | + | ==Labs working on this gene== |
| − | [[File: ZFP179 4.jpg|right|thumb|300px|'''Figure 2.''' ''Proposed Role of SERF1 during the Initial Response to Salt Stress.(from reference <ref name="ref1"/>)'']]
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| − | *In summary, ''Schmidt et al.'' discovered an H<sub>2</sub>O<sub>2</sub>-mediated molecular signaling cascade important for the initial response to salinity in rice (Figure 2). ''SERF1'' is a phosphorylation target of a salt-responsive MAPK, thereby promoting the expression of MAPK cascade genes (''MAPK5'' and ''MAP3K6''), salt tolerance–mediating TF genes (''ZFP179'' and ''DREB2A''), and itself through direct interaction with the corresponding promoters in planta.
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| − | *In essence, salt stress results in a wave of H<sub>2</sub>O<sub>2</sub> production<ref name="ref6"/> that activates ''SERF1'' through the MAPK pathway. Posttranslational regulation of H<sub>2</sub>O<sub>2</sub>-dependent SERF1 expression is consistent with the observation that ROS signals occur rapidly during environmental changes<ref name="ref6"/><ref name="ref7"/>.
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| − | *This first ROS wave is propagated at the transcriptional level through SERF1. However, as the transcriptional activity of SERF1 is modulated by phosphorylation, only a persistent salt stress signal will further boost the expression of target genes. In such a scenario, a transient stress can be sensed rapidly, and activation of stress genes is stopped before full activation of the acclimation program. Among the plant transcription factors, '''ethylene response factor (ERF)''' is one of the largest '''subfamilies of Apetala2 (AP2)/ERF transcription factor family''' and is '''characterized with single AP2 domain'''. ERFs are a double-edged sword; though most of the ERFs are activators of stress-responsive genes, certain ERF could act as repressor<ref name="ref1"/><ref name="ref8"/>.
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| − | The expression of ERFs may be ethylene dependent or independent and is regulated by feedback mechanism. Apart from above regulation mechanism, expressions of ERFs are post-transcriptionally regulated by microRNAs (miRNAs), and miRNA expressions are in turn regulated by ERFs<ref name="ref8"/>.
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| | + | ==References== |
| | + | Please input cited references here. |
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| − | ==Labs working on this gene== | + | ==Structured Information== |
| − | *Institute of Biochemistry and Biology, University of Potsdam, 14476 Potsdam, Germany
| + | [[Category:Genes]][[Category:Oryza Sativa Japonica Group]][[Category:Japonica Chromosome 05]] |
| − | *Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam, Germany
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| − | *Centre de Coopération Internationale en Recherche Agronomique pour le Développement, Unité Mixte de Recherche, Genetic Improvement and Adaptation of Mediterranean and Tropical Plants, 34398 Montpellier, cedex 5, France
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| − | *Department of Molecular Genetics, Centre for Research in Agricultural Genomics, Consejo Superior de Investigaciones Científicos, Institute of Agro-food Research and Technology, Autonomus University of Barcelona, University of Barcelona, Bellaterra (Cerdanyola del Vallés), 08193 Barcelona, Spain
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| − | ===References===
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| − | <references>
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| − | * <ref name="ref1">
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| − | Schmidt R, Mieulet D, Hubberten H M, et al. SALT-RESPONSIVE ERF1 regulates reactive oxygen species–dependent signaling during the initial response to salt stress in rice[J]. The Plant Cell Online, 2013, 25(6): 2115-2131.
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| − | </ref>
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| − | * <ref name="ref2">
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| − | Schmidt R, Caldana C, Mueller-Roeber B, et al. The contribution of SERF1 to root-to-shoot signaling during salinity stress in rice[J]. Plant signaling & behavior, 2014, 9(1): e27540.
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| − | </ref>
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| − | * <ref name="ref3">
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| − | Schmidt R, Schippers J H M, Mieulet D, et al. SALT-RESPONSIVE ERF1 is a negative regulator of grain filling and gibberellin-mediated seedling establishment in rice[J]. Molecular plant, 2013: sst131.
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| − | </ref>
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| − | * <ref name="ref4">
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| − | Nakano T, Suzuki K, Fujimura T, et al. Genome-wide analysis of the ERF gene family in Arabidopsis and rice[J]. Plant physiology, 2006, 140(2): 411-432.
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| − | </ref>
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| − | * <ref name="ref5">
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| − | Popescu S C, Popescu G V, Bachan S, et al. MAPK target networks in Arabidopsis thaliana revealed using functional protein microarrays[J]. Genes & development, 2009, 23(1): 80-92.
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| − | </ref>
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| − | * <ref name="ref6">
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| − | Mittler R, Vanderauwera S, Suzuki N, et al. ROS signaling: the new wave?[J]. Trends in plant science, 2011, 16(6): 300-309.
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| − | </ref>
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| − | * <ref name="ref7">
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| − | Hong C Y, Chao Y Y, Yang M Y, et al. NaCl-induced expression of glutathione reductase in roots of rice (Oryza sativa L.) seedlings is mediated through hydrogen peroxide but not abscisic acid[J]. Plant and soil, 2009, 320(1-2): 103-115.
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| − | </ref>
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| − | * <ref name="ref8">
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| − | Thirugnanasambantham K, Durairaj S, Saravanan S, et al. Role of Ethylene Response Transcription Factor (ERF) and Its Regulation in Response to Stress Encountered by Plants[J]. Plant Molecular Biology Reporter, 2014: 1-11.
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| − | </ref>
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| − | </references>
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