The phytohormone auxin plays a pivotal role in governing plant growth and development.Although the TRANSPORT INHIBITOR RESPONSE1/AUXIN SIGNALING F-BOX(TIR1/AFB)receptors function in both the nucleus and cytoplasm,the ...The phytohormone auxin plays a pivotal role in governing plant growth and development.Although the TRANSPORT INHIBITOR RESPONSE1/AUXIN SIGNALING F-BOX(TIR1/AFB)receptors function in both the nucleus and cytoplasm,the mechanism governing the distribution of TIR1/AFBs between these cellular compartments remains unknown.In this study,we demonstrate that auxin-mediated oxidation of TIR1/AFB2 is essential for their targeting to the nucleus.We showed that small active molecules,reactive oxygen species(ROS)and nitric oxide(NO),are indispensable for the nucleo-cytoplasmic distribution of TIR1/AFB2 in trichoblasts and root hairs.Further studies revealed that this process is regulated by the FERONIA receptor kinase–NADPH oxidase signaling pathway.Interestingly,ROS and NO initiate oxidative modifications in TIR1C140/516 and AFB2C135/511,facilitating their subsequent nuclear import.The oxidized forms of TIR1C140/516 and AFB2C135/511 play a crucial role in enhancing the function of TIR1 and AFB2 in transcriptional auxin responses.Collectively,our study reveals a novel mechanism by which auxin stimulates the transport of TIR1/AFB2 from the cytoplasm to the nucleus,orchestrated by the FERONIA–ROS signaling pathway.展开更多
Dear Editor,Auxin is the major plant hormone regulating growth and development(Friml,2022).Forward genetic approaches have identified major components of auxin signaling and established the canonical mechanism mediati...Dear Editor,Auxin is the major plant hormone regulating growth and development(Friml,2022).Forward genetic approaches have identified major components of auxin signaling and established the canonical mechanism mediating transcriptional and thus developmental reprogramming in Arabidopsis thaliana.In this textbook view,TRANSPORT INHIBITOR RESPONSE 1(TIR1)/AUXIN-SIGNALING F-BOX(AFB)proteins are auxin receptors,which act as F-box subunits determining the substrate specificity of the Skp1-Cullin1-F box protein(SCF)type E3 ubiquitin ligase complex.Auxin acts as a"molecular glue,"increasing the affinity between TIR1/AFBs and the Auxin/lndole-3-Acetic Acid(Aux/IAA)repressors.Subsequently,Aux/IAAs are ubiquitinated and degraded,thus releasing auxin transcription factors from their repression and making them free to mediate transcription of auxin response genes(Yu et al.,2022).展开更多
In Arabidopsis thaliana,canonical auxin-dependent gene regulation is mediated by 23 transcription factors from the AUXIN RESPONSE FACTOR(ARF)family that interact with auxin/indole acetic acid repressors(Aux/IAAs),whic...In Arabidopsis thaliana,canonical auxin-dependent gene regulation is mediated by 23 transcription factors from the AUXIN RESPONSE FACTOR(ARF)family that interact with auxin/indole acetic acid repressors(Aux/IAAs),which themselves form co-receptor complexes with one of six TRANSPORT INHIBITOR*!/AUXIN-SIGNALLING F-BOX(TIR1/AFB)proteins.Different combinations of co-receptors drive specific sensing outputs,allowing auxin to control a myriad of processes.ARF6 and ARF8 are positive regulators of adventitious root initiation upstream of jasmonate,but the exact auxin co-receptor complexes controlling the transcriptional activity of these proteins has remained unknown.Here,using loss-of-function mutants we show that three Aux/IAA genes,IAA6,IAA9,and IAA17,act additively in the control of adventitious root(AR)initiation.These three IAA proteins interact with ARF6 and/or ARF8 and likely repress their activity in AR development.We show that TIR1 and AFB2 are positive regulators of AR formation and TIR1 plays a dual role in the control of jasmonic acid(JA)biosynthesis and conjugation,as several JA biosynthesis genes are up-regulated in the tir1-1 mutant.These results lead us to propose that in the presence of auxin,TIR1 and AFB2 form specific sensing complexes with IAA6,IAA9,and/or IAA17 to modulate JA homeostasis and control AR initiation.展开更多
Protein–protein interaction(PPI)network analysis is an effective method to identify key proteins during plant development,especially in species for which basic molecular research is lacking,such as apple(Malus domest...Protein–protein interaction(PPI)network analysis is an effective method to identify key proteins during plant development,especially in species for which basic molecular research is lacking,such as apple(Malus domestica).Here,an MdPPI network containing 30806 PPIs was inferred in apple and its quality and reliability were rigorously verified.Subsequently,a rootgrowth subnetwork was extracted to screen for critical proteins in root growth.Because hormone-related proteins occupied the largest proportion of critical proteins,a hormonerelated sub-subnetwork was further extracted from the root-growth subnetwork.Among these proteins,auxin-related M.domestica TRANSPORT INHIBITOR RESISTANT 1(MdTIR1)served as the central,high-degree node,implying that this protein exerts essential roles in root growth.Furthermore,transgenic apple roots overexpressing an MdTIR1 transgene displayed increased primary root elongation.Expression analysis showed that MdTIR1 significantly upregulated auxin-responsive genes in apple roots,indicating that it mediates root growth in an auxin-dependent manner.Further experimental validation revealed that MdTIR1 interacted with and accelerated the degradation of MdIAA28,MdIAA43,andMdIAA46.Thus,MdTIR1-mediated degradation of MdIAAs is critical in auxin signal transduction and root growth regulation in apple.Moreover,our network analysis and high-degree node screening provide a novel research technique for more generally characterizing molecular mechanisms.展开更多
The auxin receptor(TIR1/AFBs)family encodes the F-box protein subunit,which is involved in the formation of the E3 ubiquitin ligase SCFTIR1/AFBs complex,a key component of the auxin signaling pathway.However,there are...The auxin receptor(TIR1/AFBs)family encodes the F-box protein subunit,which is involved in the formation of the E3 ubiquitin ligase SCFTIR1/AFBs complex,a key component of the auxin signaling pathway.However,there are few studies on the auxin receptor family in apple(Malus×domestica).In this study,eight MdAFBs were identified,and phylogenetic analysis showed that they were classified into four groups and distributed on eight chromosomes.Herein,a comprehensive analysis of the MdAFB gene family was conducted to identify cis-acting elements,gene structures,protein structures,aligned sequences,conserved motifs,conserved amino acids,and the protein–protein interaction network.The results of yeast two-hybrid assays showed that MdAFB1 interacted with three auxin repressor proteins.The results of qRT-PCR showed that MdAFB1 responded to osmotic and salt stress.The overexpression of MdAFB1 increased osmotic and salt resistance in apple calli,and the ectopic expression of MdAFB1 enhanced osmotic and salt tolerance in Arabidopsis.This study provided a basis for the identification of auxin receptor genes in apple and their functions in mediating osmotic and salt stress.展开更多
基金supported by grants from the National Natural Science Foundation of China(32230009,31770307,31972863)the Science and Technology Innovation Plan Of Shanghai Science and Technology Commission(20ZR1416500).
文摘The phytohormone auxin plays a pivotal role in governing plant growth and development.Although the TRANSPORT INHIBITOR RESPONSE1/AUXIN SIGNALING F-BOX(TIR1/AFB)receptors function in both the nucleus and cytoplasm,the mechanism governing the distribution of TIR1/AFBs between these cellular compartments remains unknown.In this study,we demonstrate that auxin-mediated oxidation of TIR1/AFB2 is essential for their targeting to the nucleus.We showed that small active molecules,reactive oxygen species(ROS)and nitric oxide(NO),are indispensable for the nucleo-cytoplasmic distribution of TIR1/AFB2 in trichoblasts and root hairs.Further studies revealed that this process is regulated by the FERONIA receptor kinase–NADPH oxidase signaling pathway.Interestingly,ROS and NO initiate oxidative modifications in TIR1C140/516 and AFB2C135/511,facilitating their subsequent nuclear import.The oxidized forms of TIR1C140/516 and AFB2C135/511 play a crucial role in enhancing the function of TIR1 and AFB2 in transcriptional auxin responses.Collectively,our study reveals a novel mechanism by which auxin stimulates the transport of TIR1/AFB2 from the cytoplasm to the nucleus,orchestrated by the FERONIA–ROS signaling pathway.
基金the European Research Council Advanced Grant(ETAP-742985).
文摘Dear Editor,Auxin is the major plant hormone regulating growth and development(Friml,2022).Forward genetic approaches have identified major components of auxin signaling and established the canonical mechanism mediating transcriptional and thus developmental reprogramming in Arabidopsis thaliana.In this textbook view,TRANSPORT INHIBITOR RESPONSE 1(TIR1)/AUXIN-SIGNALING F-BOX(AFB)proteins are auxin receptors,which act as F-box subunits determining the substrate specificity of the Skp1-Cullin1-F box protein(SCF)type E3 ubiquitin ligase complex.Auxin acts as a"molecular glue,"increasing the affinity between TIR1/AFBs and the Auxin/lndole-3-Acetic Acid(Aux/IAA)repressors.Subsequently,Aux/IAAs are ubiquitinated and degraded,thus releasing auxin transcription factors from their repression and making them free to mediate transcription of auxin response genes(Yu et al.,2022).
文摘In Arabidopsis thaliana,canonical auxin-dependent gene regulation is mediated by 23 transcription factors from the AUXIN RESPONSE FACTOR(ARF)family that interact with auxin/indole acetic acid repressors(Aux/IAAs),which themselves form co-receptor complexes with one of six TRANSPORT INHIBITOR*!/AUXIN-SIGNALLING F-BOX(TIR1/AFB)proteins.Different combinations of co-receptors drive specific sensing outputs,allowing auxin to control a myriad of processes.ARF6 and ARF8 are positive regulators of adventitious root initiation upstream of jasmonate,but the exact auxin co-receptor complexes controlling the transcriptional activity of these proteins has remained unknown.Here,using loss-of-function mutants we show that three Aux/IAA genes,IAA6,IAA9,and IAA17,act additively in the control of adventitious root(AR)initiation.These three IAA proteins interact with ARF6 and/or ARF8 and likely repress their activity in AR development.We show that TIR1 and AFB2 are positive regulators of AR formation and TIR1 plays a dual role in the control of jasmonic acid(JA)biosynthesis and conjugation,as several JA biosynthesis genes are up-regulated in the tir1-1 mutant.These results lead us to propose that in the presence of auxin,TIR1 and AFB2 form specific sensing complexes with IAA6,IAA9,and/or IAA17 to modulate JA homeostasis and control AR initiation.
基金supported by the National Natural Science Foundation of China(31972357,31901574,and 31772254)the National Key R&D Program of China(2019YFD1000104)。
文摘Protein–protein interaction(PPI)network analysis is an effective method to identify key proteins during plant development,especially in species for which basic molecular research is lacking,such as apple(Malus domestica).Here,an MdPPI network containing 30806 PPIs was inferred in apple and its quality and reliability were rigorously verified.Subsequently,a rootgrowth subnetwork was extracted to screen for critical proteins in root growth.Because hormone-related proteins occupied the largest proportion of critical proteins,a hormonerelated sub-subnetwork was further extracted from the root-growth subnetwork.Among these proteins,auxin-related M.domestica TRANSPORT INHIBITOR RESISTANT 1(MdTIR1)served as the central,high-degree node,implying that this protein exerts essential roles in root growth.Furthermore,transgenic apple roots overexpressing an MdTIR1 transgene displayed increased primary root elongation.Expression analysis showed that MdTIR1 significantly upregulated auxin-responsive genes in apple roots,indicating that it mediates root growth in an auxin-dependent manner.Further experimental validation revealed that MdTIR1 interacted with and accelerated the degradation of MdIAA28,MdIAA43,andMdIAA46.Thus,MdTIR1-mediated degradation of MdIAAs is critical in auxin signal transduction and root growth regulation in apple.Moreover,our network analysis and high-degree node screening provide a novel research technique for more generally characterizing molecular mechanisms.
基金supported by the National Natural Science Foundation of China(Grant Nos.32172538,31972378)China Agriculture Research System of MOF and MARA(Grant CARS-27).
文摘The auxin receptor(TIR1/AFBs)family encodes the F-box protein subunit,which is involved in the formation of the E3 ubiquitin ligase SCFTIR1/AFBs complex,a key component of the auxin signaling pathway.However,there are few studies on the auxin receptor family in apple(Malus×domestica).In this study,eight MdAFBs were identified,and phylogenetic analysis showed that they were classified into four groups and distributed on eight chromosomes.Herein,a comprehensive analysis of the MdAFB gene family was conducted to identify cis-acting elements,gene structures,protein structures,aligned sequences,conserved motifs,conserved amino acids,and the protein–protein interaction network.The results of yeast two-hybrid assays showed that MdAFB1 interacted with three auxin repressor proteins.The results of qRT-PCR showed that MdAFB1 responded to osmotic and salt stress.The overexpression of MdAFB1 increased osmotic and salt resistance in apple calli,and the ectopic expression of MdAFB1 enhanced osmotic and salt tolerance in Arabidopsis.This study provided a basis for the identification of auxin receptor genes in apple and their functions in mediating osmotic and salt stress.
