NAC proteins are plant-specific transcription factors and enriched with members involved in plant response to drought stress. In this study, we analyzed the expression profiles of TaNAC69 in bread wheat using Affymetr...NAC proteins are plant-specific transcription factors and enriched with members involved in plant response to drought stress. In this study, we analyzed the expression profiles of TaNAC69 in bread wheat using Affymetrix Wheat Genome Array datasets and quantitative RT-PCR. TaNAC69 expression was positively associated with wheat responses to both abiotic and biotic stresses and was closely correlated with a number of stress up-regulated genes. The functional analyses of TaNAC69 in transgenic wheat showed that TaNAC69 driven by a barley drought-inducible HvDhn4s promoter led to marked drought-inducible overexpression of TaNAC69 in the leaves and roots of transgenic lines. The HvDhn4s：Ta- NAC69 transgenic lines produced more shoot biomass under combined mild salt stress and water-limitation conditions, had longer root and more root biomass under polyethylene glycol-induced dehydration. Analysis of transgenic lines with constitutive overexpression of TaNAC69 showed the enhanced expression levels of several stress up-regulated genes. DNA-binding assays revealed that TaNAC69 and its rice homolog （ONAC131） were capable of binding to the promoter elements of three rice genes （chitinase, ZlM, and glyoxalase I） and an Arabidopsis glyoxalase I family gene, which are homologs of TaNAC69 up-regulated stress genes. These data suggest that TaNAC69 is involved in regulating stress upregulated genes and wheat adaptation to drought stress.展开更多
We report here that ORS1, a previously uncharacterized member of the NAC transcription factor family, controls leaf senescence in Arabidopsis thaliana. Overexpression of ORS1 accelerates senescence in transgenic plant...We report here that ORS1, a previously uncharacterized member of the NAC transcription factor family, controls leaf senescence in Arabidopsis thaliana. Overexpression of ORS1 accelerates senescence in transgenic plants, whereas its inhibition delays it. Genes acting downstream of ORS1 were identified by global expression analysis using transgenic plants producing dexamethasone-inducible ORSl-GR fusion protein. Of the 42 up-regulated genes, 30 （-70%） were pre- viously shown to be up-regulated during age-dependent senescence, We also observed that 32 （-76%） of the ORSl-dependent genes were induced by long-term （4 d）, but not short-term （6 h） salinity stress （150 mM NaCI）. Furthermore, expression of 16 and 24 genes, respectively, was induced after 1 and 5 h of treatment with hydrogen peroxide （H2O2）, a reactive oxygen species known to accumulate during salinity stress. ORS1 itself was found to be rapidly and strongly induced by H2O2 treatment in both leaves and roots. Using in vitro binding site selection, we determined the preferred binding motif of ORS1 and found it to be present in half of the ORSl-dependent genes. ORS1 is a paralog of ORE1/ ANACO92/AtNAC2, a previously reported regulator of leaf senescence. Phylogenetic footprinting revealed evolutionary conservation of the ORS1 and ORE1 promoter sequences in different Brassicaceae species, indicating strong positive selection acting on both genes. We conclude that ORS1, similarly to ORE1, triggers expression of senescence-associated genes through a regulatory network that may involve cross-talk with saltand H2O2-dependent signaling pathways.展开更多
Senescence is a highly regulated process that involves the action of a large number of transcription factors. The NAC transcription factor ORE1 （ANAC092） has recently been shown to play a critical role in positively...Senescence is a highly regulated process that involves the action of a large number of transcription factors. The NAC transcription factor ORE1 （ANAC092） has recently been shown to play a critical role in positively controlling senescence in Arabidopsis thaliana; however, no direct target gene through which it exerts its molecular function has been identified previously. Here, we report that BIFUNCTIONAL NUCLEASE1 （BFN1）, a well-known senescence-enhanced gene, is directly regulated by ORE1. We detected elevated expression of BFN1 already 2 h after induction of ORE1 in estradiol-inducible ORE1 overexpression lines and 6 h after transfection of Arabidopsis mesophyll cell protoplasts with a 35S：ORE1 construct, ORE1 and BFN1 expression patterns largely overlap, as shown by promoter-reporter gene （GUS） fusions, while BFN1 expression in senescent leaves and the abscission zones of maturing flower organs was virtually absent in ore1 mutant background. In vitro binding site assays revealed a bipartite ORE1 binding site, similar to that of ORS1, a paralog of ORE1. A bipartite ORE1 binding site was identified in the BFN1 promoter; mutating the cis-element within the context of the full-length BFN1 promoter drastically reduced OREl-mediated transactivation capacity in tran- siently transfected Arabidopsis mesophyll cell protoplasts. Furthermore, chromatin immunoprecipitation （CHIP） demon- strates in vivo binding of ORE1 to the BFN1 promoter. We also demonstrate binding of ORE1 in vivo to the promoters of two other senescence-associated genes, namely SAG29/SWEET15 and SINA1, supporting the central role of ORE1 during senescence.展开更多
文摘NAC proteins are plant-specific transcription factors and enriched with members involved in plant response to drought stress. In this study, we analyzed the expression profiles of TaNAC69 in bread wheat using Affymetrix Wheat Genome Array datasets and quantitative RT-PCR. TaNAC69 expression was positively associated with wheat responses to both abiotic and biotic stresses and was closely correlated with a number of stress up-regulated genes. The functional analyses of TaNAC69 in transgenic wheat showed that TaNAC69 driven by a barley drought-inducible HvDhn4s promoter led to marked drought-inducible overexpression of TaNAC69 in the leaves and roots of transgenic lines. The HvDhn4s：Ta- NAC69 transgenic lines produced more shoot biomass under combined mild salt stress and water-limitation conditions, had longer root and more root biomass under polyethylene glycol-induced dehydration. Analysis of transgenic lines with constitutive overexpression of TaNAC69 showed the enhanced expression levels of several stress up-regulated genes. DNA-binding assays revealed that TaNAC69 and its rice homolog （ONAC131） were capable of binding to the promoter elements of three rice genes （chitinase, ZlM, and glyoxalase I） and an Arabidopsis glyoxalase I family gene, which are homologs of TaNAC69 up-regulated stress genes. These data suggest that TaNAC69 is involved in regulating stress upregulated genes and wheat adaptation to drought stress.
文摘We report here that ORS1, a previously uncharacterized member of the NAC transcription factor family, controls leaf senescence in Arabidopsis thaliana. Overexpression of ORS1 accelerates senescence in transgenic plants, whereas its inhibition delays it. Genes acting downstream of ORS1 were identified by global expression analysis using transgenic plants producing dexamethasone-inducible ORSl-GR fusion protein. Of the 42 up-regulated genes, 30 （-70%） were pre- viously shown to be up-regulated during age-dependent senescence, We also observed that 32 （-76%） of the ORSl-dependent genes were induced by long-term （4 d）, but not short-term （6 h） salinity stress （150 mM NaCI）. Furthermore, expression of 16 and 24 genes, respectively, was induced after 1 and 5 h of treatment with hydrogen peroxide （H2O2）, a reactive oxygen species known to accumulate during salinity stress. ORS1 itself was found to be rapidly and strongly induced by H2O2 treatment in both leaves and roots. Using in vitro binding site selection, we determined the preferred binding motif of ORS1 and found it to be present in half of the ORSl-dependent genes. ORS1 is a paralog of ORE1/ ANACO92/AtNAC2, a previously reported regulator of leaf senescence. Phylogenetic footprinting revealed evolutionary conservation of the ORS1 and ORE1 promoter sequences in different Brassicaceae species, indicating strong positive selection acting on both genes. We conclude that ORS1, similarly to ORE1, triggers expression of senescence-associated genes through a regulatory network that may involve cross-talk with saltand H2O2-dependent signaling pathways.
文摘Senescence is a highly regulated process that involves the action of a large number of transcription factors. The NAC transcription factor ORE1 （ANAC092） has recently been shown to play a critical role in positively controlling senescence in Arabidopsis thaliana; however, no direct target gene through which it exerts its molecular function has been identified previously. Here, we report that BIFUNCTIONAL NUCLEASE1 （BFN1）, a well-known senescence-enhanced gene, is directly regulated by ORE1. We detected elevated expression of BFN1 already 2 h after induction of ORE1 in estradiol-inducible ORE1 overexpression lines and 6 h after transfection of Arabidopsis mesophyll cell protoplasts with a 35S：ORE1 construct, ORE1 and BFN1 expression patterns largely overlap, as shown by promoter-reporter gene （GUS） fusions, while BFN1 expression in senescent leaves and the abscission zones of maturing flower organs was virtually absent in ore1 mutant background. In vitro binding site assays revealed a bipartite ORE1 binding site, similar to that of ORS1, a paralog of ORE1. A bipartite ORE1 binding site was identified in the BFN1 promoter; mutating the cis-element within the context of the full-length BFN1 promoter drastically reduced OREl-mediated transactivation capacity in tran- siently transfected Arabidopsis mesophyll cell protoplasts. Furthermore, chromatin immunoprecipitation （CHIP） demon- strates in vivo binding of ORE1 to the BFN1 promoter. We also demonstrate binding of ORE1 in vivo to the promoters of two other senescence-associated genes, namely SAG29/SWEET15 and SINA1, supporting the central role of ORE1 during senescence.
