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
Leaf senescence,the final stage of leaf development,is influenced by numerous internal and environmental signals.So far,how biotic stresses such as pathogen infection regulate leaf senescence is unclear.Here,we found ...Leaf senescence,the final stage of leaf development,is influenced by numerous internal and environmental signals.So far,how biotic stresses such as pathogen infection regulate leaf senescence is unclear.Here,we found that the premature leaf senescence caused by a soil-borne vascular fungus Verticillium dahliae in Arabidopsis was impaired by the mutation of a protein elicitor from V.dahliae 1(PevD1).Constitutive or inducible overexpression of PevD1 accelerated Arabidopsis leaf senescence.A senescence-associated NAC transcription factor,ORE1,was targeted by PevD1.PevD1 interacted with and stabilized ORE1 protein by disrupting its interaction with the RING-type ubiquitin E3 ligase NLA.Mutation of ORE1 suppressed the premature senescence caused by overexpressing PevD1.Overexpression of ORE1 or PevD1 led to enhanced ethylene production,and ORE1 mediated PevD1-induced ethylene biosynthesis by directly binding to the ACS6 promoter.Loss-of-function of ACSs suppressed V.dahliae-induced leaf senescence in ORE1-overexpressing plants.Interestingly,PevD1 also interacted with Gossypium hirsutum ORE1(GhORE1),and virus-induced gene silencing of GhORE1 delayed V.dahliae-triggered leaf senescence in cotton,indicative of the existence of a conserved mechanism in plants.Altogether,our study demonstrates that V.dahliae induces leaf senescence by secreting the effector PevD1 to regulate the ORE1-ACS6 cascade,providing new insight into biotic stress-induced senescence in plants.展开更多
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.
基金This work was supported by the National Natural Science Foundation of China(31970196 and 32011540381 to Z.L.,31900173 to H.W.,31770649 to X.X.)the National Key Research and Development Program of China(No.2019YFA0903904 to H.G.)+2 种基金Shenzhen Science and Technology Program(KQTD20190929173906742 to H.G.)China Postdoctoral Science Foundation(2019M650514 to Y.Z.and 2020M670544 to Y.G.,and 2019M650516 to H.W.)the startup funding for plant aging research from"Beijing Advanced Innovation Center for Tree Breeding by Molecular Design,Beijing Forestry University".
文摘Leaf senescence,the final stage of leaf development,is influenced by numerous internal and environmental signals.So far,how biotic stresses such as pathogen infection regulate leaf senescence is unclear.Here,we found that the premature leaf senescence caused by a soil-borne vascular fungus Verticillium dahliae in Arabidopsis was impaired by the mutation of a protein elicitor from V.dahliae 1(PevD1).Constitutive or inducible overexpression of PevD1 accelerated Arabidopsis leaf senescence.A senescence-associated NAC transcription factor,ORE1,was targeted by PevD1.PevD1 interacted with and stabilized ORE1 protein by disrupting its interaction with the RING-type ubiquitin E3 ligase NLA.Mutation of ORE1 suppressed the premature senescence caused by overexpressing PevD1.Overexpression of ORE1 or PevD1 led to enhanced ethylene production,and ORE1 mediated PevD1-induced ethylene biosynthesis by directly binding to the ACS6 promoter.Loss-of-function of ACSs suppressed V.dahliae-induced leaf senescence in ORE1-overexpressing plants.Interestingly,PevD1 also interacted with Gossypium hirsutum ORE1(GhORE1),and virus-induced gene silencing of GhORE1 delayed V.dahliae-triggered leaf senescence in cotton,indicative of the existence of a conserved mechanism in plants.Altogether,our study demonstrates that V.dahliae induces leaf senescence by secreting the effector PevD1 to regulate the ORE1-ACS6 cascade,providing new insight into biotic stress-induced senescence in plants.
