Artigos
URI permanente para esta coleçãohttps://locus.ufv.br/handle/123456789/11847
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Item Repeat variants for the SbMATE transporter protect sorghum roots from aluminum toxicity by transcriptional interplay in cis and trans(PNAS, 2019-01-02) Martins, Laura G. C.; Pimenta, Maiana R.; Duarte, Christiane E. M.; Fontes, Elizabeth P. B.; Melo, Janaina O.; Barros, Beatriz A.; Lana, Ubiraci G. P.; Pastina, Maria M.; Guimaraes, Claudia T.; Schaffer, Robert E.; Kochian, Leon V.; Magalhaes, Jurandir V.Acidic soils, where aluminum (Al) toxicity is a major agricultural constraint, are globally widespread and are prevalent in developing countries. In sorghum, the root citrate transporter SbMATE confers Al tolerance by protecting root apices from toxic Al3+, but can exhibit reduced expression when introgressed into different lines. We show that allele-specific SbMATE transactivation occurs and is caused by factors located away from SbMATE. Using expression-QTL mapping and expression genome-wide association mapping, we establish that SbMATE transcription is controlled in a bipartite fashion, primarily in cis but also in trans. Multiallelic promoter transactivation and ChIP analyses demonstrated that intermolecular effects on SbMATE expression arise from a WRKY and a zinc finger-DHHC transcription factor (TF) that bind to and trans-activate the SbMATE promoter. A haplotype analysis in sorghum RILs indicates that the TFs influence SbMATE expression and Al tolerance. Variation in SbMATE expression likely results from changes in tandemly repeated cis sequences flanking a transposable element (a miniature inverted repeat transposable element) insertion in the SbMATE promoter, which are recognized by the Al3+-responsive TFs. According to our model, repeat expansion in Al-tolerant genotypes increases TF recruitment and, hence, SbMATE expression, which is, in turn, lower in Al-sensitive genetic backgrounds as a result of lower TF expression and fewer binding sites. We thus show that even dominant cis regulation of an agronomically important gene can be subjected to precise intermolecular fine-tuning. These concerted cis/trans interactions, which allow the plant to sense and respond to environmental cues, such as Al3+ toxicity, can now be used to increase yields and food security on acidic soils.Item A WW domain-containing protein forms immune nuclear bodies against begomoviruses(Molecular Plant, 2018-12-03) Calil, Iara P.; Quadros, Iana P. S.; Araújo, Thais C.; Duarte, Christiane E. M.; Gouveia-Mageste, Bianca C.; Silva, José Cleydson F.; Brustolini, Otávio J. B.; Teixeira, Ruan M.; Oliveira, Cauê N.; Milagres, Rafael W. M. M.; Martins, Gilberto S.; Reis, Pedro A. B.; Machado, Joao Paulo B.; Fontes, Elizabeth P. B.; Chory, JoanneThe bipartite begomoviruses (Geminiviridae family), which are DNA viruses that replicate in the nucleus of infected cells, encode the nuclear shuttle protein (NSP) to facilitate the translocation of viral DNA from the nucleus to the cytoplasm via nuclear pores. This intracellular trafficking of NSP–DNA complexes is accessorized by the NSP-interacting guanosine triphosphatase (NIG) at the cytosolic side. Here, we report the nuclear redistribution of NIG by AtWWP1, a WW domain-containing protein that forms immune nuclear bodies (NBs) against begomoviruses. We demonstrated that AtWWP1 relocates NIG from the cytoplasm to the nucleus where it is confined to AtWWP1-NBs, suggesting that the NIG-AtWWP1 interaction may interfere with the NIG pro-viral function associated with its cytosolic localization. Consistent with this assumption, loss of AtWWP1 function cuased plants more susceptible to begomovirus infection, whereas overexpression of AtWWP1 enhanced plant resistance to begomovirus. Furthermore, we found that a mutant version of AtWWP1 defective for NB formation was no longer capable of interacting with and relocating NIG to the nucleus and lost its immune function against begomovirus. The antiviral function of AtWWP1-NBs, however, could be antagonized by viral infection that induced either the disruption or a decrease in the number of AtWWP1-NBs. Collectively, these results led us to propose that AtWWP1 organizes nuclear structures into nuclear foci, which provide intrinsic immunity against begomovirus infection.Item Revisiting the soybean GmNAC superfamily(Frontiers in Plant Science, 2018-12) Melo, Bruno P.; Fraga, Otto T.; Silva, José Cleydson F.; Ferreira, Dalton O.; Brustolini, Otávio J. B.; Carpinetti, Paola A.; Machado, Joao Paulo B.; Reis, Pedro A. B.; Fontes, Elizabeth P. B.The NAC (NAM, ATAF, and CUC) genes encode transcription factors involved with the control of plant morph-physiology and stress responses. The release of the last soybean (Glycine max) genome assembly (Wm82.a2.v1) raised the possibility that new NAC genes would be present in the soybean genome. Here, we interrogated the last version of the soybean genome against a conserved NAC domain structure. Our analysis identified 32 putative novel NAC genes, updating the superfamily to 180 gene members. We also organized the genes in 15 phylogenetic subfamilies, which showed a perfect correlation among sequence conservation, expression profile, and function of orthologous Arabidopsis thaliana genes and NAC soybean genes. To validate our in silico analyses, we monitored the stress-mediated gene expression profiles of eight new NAC-genes by qRT-PCR and monitored the GmNAC senescence-associated genes by RNA-seq. Among ER stress, osmotic stress and salicylic acid treatment, all the novel tested GmNAC genes responded to at least one type of stress, displaying a complex expression profile under different kinetics and extension of the response. Furthermore, we showed that 40% of the GmNACs were differentially regulated by natural leaf senescence, including eight (8) newly identified GmNACs. The developmental and stress-responsive expression profiles of the novel NAC genes fitted perfectly with their phylogenetic subfamily. Finally, we examined two uncharacterized senescence-associated proteins, GmNAC065 and GmNAC085, and a novel, previously unidentified, NAC protein, GmNAC177, and showed that they are nuclear localized, and except for GmNAC065, they display transactivation activity in yeast. Consistent with a role in leaf senescence, transient expression of GmNAC065 and GmNAC085 induces the appearance of hallmarks of leaf senescence, including chlorophyll loss, leaf yellowing, lipid peroxidation and accumulation of H 2 O 2 . GmNAC177 was clustered to an uncharacterized subfamily but in close proximity to the TIP subfamily. Accordingly, it was rapidly induced by ER stress and by salicylic acid under late kinetic response and promoted cell death in planta. Collectively, our data further substantiated the notion that the GmNAC genes display functional and expression profiles consistent with their phylogenetic relatedness and established a complete framework of the soybean NAC superfamily as a foundation for future analyses.Item Complete inventory of soybean NAC transcription factors: Sequence conservation and expression analysis uncover their distinct roles in stress response(Gene, 2009-09-01) Pinheiro, Guilherme L.; Marques, Carolina S.; Costa, Maximiller D.B.L.; Reis, Pedro A. B.; Alves, Murilo S.; Carvalho, Claudine M.; Fietto, Luciano G.; Fontes, Elizabeth P. B.We performed an inventory of soybean NAC transcription factors, in which 101 NAC domain-containing proteins were annotated into 15 different subgroups, showing a clear relationship between structure and function. The six previously described GmNAC proteins (GmNAC1 to GmNAC6) were located in the nucleus and a transactivation assay in yeast confirmed that GmNAC2, GmNAC3, GmNAC4 and GmNAC5 function as transactivators. We also analyzed the expression of the six NAC genes in response to a variety of stress conditions. GmNAC2, GmNAC3 and GmNAC4 were strongly induced by osmotic stress. GmNAC3 and GmNAC4 were also induced by ABA, JA and salinity but differed in their response to cold. Consistent with an involvement in cell death programs, the transient expression of GmNAC1, GmNAC5 and GmNAC6 in tobacco leaves resulted in cell death and enhanced expression of senescence markers. Our results indicate that the described soybean NACs are functionally non-redundant transcription factors involved in response to abiotic stresses and in cell death events in soybean.Item NIK1-mediated translation suppression functions as a plant antiviral immunity mechanism(Nature, 2015-04-30) Zorzatto, Cristiane; Machado, João Paulo B.; Lopes, Kênia V. G.; Nascimento, Kelly J. T.; Pereira, Welison A.; Brustolini, Otávio J. B.; Reis, Pedro A. B.; Calil, Iara P.; Deguchi, Michihito; Sachetto-Martins, Gilberto; Gouveia, Bianca C.; Loriato, Virgílio A. P.; Silva, Marcos A. C.; Silva, Fabyano F.; Santos, Anésia A.; Chory, Joanne; Fontes, Elizabeth P. B.Plants and plant pathogens are subject to continuous co-evolutionary pressure for dominance, and the outcomes of these interactions can substantially impact agriculture and food security^ 1–3 . In virus– plant interactions, one of the major mechanisms for plant antiviral immunity relies on RNA silencing, which is often suppressed by co-evolving virus suppressors, thus enhancing viral pathogenicity in susceptible hosts^ 1 . In addition, plants use the nucleotide-binding and leucine-rich repeat (NB-LRR) domain-containing resistance proteins, which recognize viral effectors to activate effector-triggered immunity in a defence mechanism similar to that employed in non-viral infections^ 2,3 . Unlike most eukaryotic organisms, plants are not known to activate mechanisms of host global translation suppression to fight viruses^ 1,2 . Here we demonstrate in Arabidopsis that the constitutive activation of NIK1, a leucine-rich repeat receptor-like kinase (LRR-RLK) identified as a virulence target of the begomovirus nuclear shuttle protein (NSP)^ 4–6 , leads to global translation suppression and translocation of the downstream component RPL10 to the nucleus, where it interacts with a newly identified MYB-like protein, L10-INTERACTING MYB DOMAIN-CONTAINING PROTEIN (LIMYB), to downregulate translational machinery genes fully. LIMYB overexpression represses ribosomal protein genes at the transcriptional level, resulting in protein synthesis inhibition, decreased viral messenger RNA association with polysome fractions and enhanced tolerance to begomovirus. By contrast, the loss of LIMYB function releases the repression of translation-related genes and increases susceptibility to virus infection. Therefore, LIMYB links immune receptor LRR-RLK activation to global translation suppression as an antiviral immunity strategy in plants.Item NIK1, a host factor specialized in antiviral defense or a novel general regulator of plant immunity?(Bioessays, 2015-09-03) Machado, Joao P. B.; Brustolini, Otavio J. B.; Mendes, Giselle C.; Santos, Anésia A.; Fontes, Elizabeth P. B.NIK1 is a receptor‐like kinase involved in plant antiviral immunity. Although NIK1 is structurally similar to the plant immune factor BAK1, which is a key regulator in plant immunity to bacterial pathogens, the NIK1‐mediated defenses do not resemble BAK1 signaling cascades. The underlying mechanism for NIK1 antiviral immunity has recently been uncovered. NIK1 activation mediates the translocation of RPL10 to the nucleus, where it interacts with LIMYB to fully down‐regulate translational machinery genes, resulting in translation inhibition of host and viral mRNAs and enhanced tolerance to begomovirus. Therefore, the NIK1 antiviral immunity response culminates in global translation suppression, which represents a new paradigm for plant antiviral defenses. Interestingly, transcriptomic analyses in nik1 mutant suggest that NIK1 may suppress antibacterial immune responses, indicating a possible opposite effect of NIK1 in bacterial and viral infections.Item A New branch of endoplasmic reticulum stress signaling and the osmotic signal converge on Plant-specific Asparagine-rich proteins to promote cell death(The Journal of biological chemistry, 2008-05-19) Costa, Maximiller D. L.; Reis, Pedro A. B.; Valente, Maria Anete S.; Irsigler, André S. T.; Carvalho, Claudine M.; Loureiro, Marcelo E.; Aragão, Francisco J. L.; Boston, Rebecca S.; Fietto, Luciano G.; Fontes, Elizabeth P. B.NRPs (N-rich proteins) were identified as targets of a novel adaptive pathway that integrates endoplasmic reticulum (ER) and osmotic stress signals based on coordinate regulation and synergistic up-regulation by tunicamycin and polyethylene gly- col treatments. This integrated pathway diverges from the molecular chaperone-inducing branch of the unfolded protein response (UPR) in several ways. While UPR-specific targets were inversely regulated by ER and osmotic stresses, NRPs required both signals for full activation. Furthermore, BiP (binding protein) overexpression in soybean prevented activa- tion of the UPR by ER stress inducers, but did not affect activa- tion of NRPs. We also found that this integrated pathway trans- duces a PCD signal generated by ER and osmotic stresses that result in the appearance of markers associated with leaf senes- cence. Overexpression of NRPs in soybean protoplasts induced caspase-3-like activity and promoted extensive DNA fragmen- tation. Furthermore, transient expression of NRPs in planta caused leaf yellowing, chlorophyll loss, malondialdehyde pro- duction, ethylene evolution, and induction of the senescence marker gene CP1. This phenotype was alleviated by the cytoki- nin zeatin, a potent senescence inhibitor. Collectively, these results indicate that ER stress induces leaf senescence through activation of plant-specific NRPs via a novel branch of the ER stress response.Item Soybean chlorotic spot virus, a novel begomovirus infecting soybean in Brazil(Archives of Virology, 2012-10-10) Coco, Daniela; Calil, Iara P.; Brustolini, Otavio J. B.; Santos, Anesia A.; Inoue-Nagata, Alice K.; Fontes, Elizabeth P. B.A novel soybean-infecting begomovirus from Brazil was identified in Jaíba, in the state of Minas Gerais, and molecularly characterized. By using rolling-circle amplification-based cloning of viral DNAs, three DNA-A variants and a cognate DNA-B were isolated from infected samples. The DNA variants share more than 98 % sequence identity but have less than 89 % identity to other reported begomovirus, the limit for demarcation of new species. In a phylogenetic analysis, both DNA-A and DNA-B clustered with other Brazilian begomoviruses. Infectious cloned DNA-A and DNA-B components induced distinct symptoms in Solanaceae and Fabaceae species by biolistic inoculation. In soybean, the virus induced mild symptoms, i.e., chlorotic spots on the leaves, from which the name soybean chlorotic spot virus (SoCSV) was proposed. The most severe symptoms were displayed by common beans, which exhibited leaf distortion, blistering, interveinal chlorosis, mosaic and golden mosaic. The possibility that SoCSV may become a threat to bean production in Brazil is discussed.Item GmNAC30 and GmNAC81 integrate the endoplasmic reticulum stress- and osmotic stress-induced cell death responses through a vacuolar processing enzyme(PNAS, 2013-09-30) Mendes, Giselle C.; Reis, Pedro A. B.; Calil, Iara P.; Carvalho, Humberto H.; Aragão, Francisco J. L.; Fontes, Elizabeth P. B.Prolonged endoplasmic reticulum and osmotic stress synergistically activate the stress-induced N-rich protein-mediated signaling that transduces a cell death signal by inducing GmNAC81 (GmNAC6) in soybean. To identify novel regulators of the stress-induced programmed cell death (PCD) response, we screened a two-hybrid library for partners of GmNAC81. We discovered another member of the NAC (NAM-ATAF1,2-CUC2) family, GmNAC30, which binds to GmNAC81 in the nucleus of plant cells to coordinately regulate common target promoters that harbor the core cis-regulatory element TGTG[TGC]. We found that GmNAC81 and GmNAC30 can function either as transcriptional repressors or activators and cooperate to enhance the transcriptional regulation of common target promoters, suggesting that heterodimerization may be required for the full regulation of gene expression. Accordingly, GmNAC81 and GmNAC30 display overlapping expression profiles in response to multiple environmental and developmental stimuli. Consistent with a role in PCD, GmNAC81 and GmNAC30 bind in vivo to and transactivate hydrolytic enzyme promoters in soybean protoplasts. A GmNAC81/GmNAC30 binding site is located in the promoter of the caspase-1–like vacuolar processing enzyme (VPE) gene, which is involved in PCD in plants. We demonstrated that the expression of GmNAC81 and GmNAC30 fully transactivates the VPE gene in soybean protoplasts and that this transactivation was associated with an increase in caspase-1–like activity. Collectively, our results indicate that the stress-induced GmNAC30 cooperates with GmNAC81 to activate PCD through the induction of the cell death executioner VPE.Item NSP-interacting kinase, NIK: a transducer of plant defence signalling(Journal of Experimental Botany, 2010-06-24) Santos, Anésia A.; Lopes, Kênia V. G.; Apfata, Jorge A. C.; Fontes, Elizabeth P. B.The NSP-interacting kinase, NIK, belongs to the five leucine-rich repeats-containing receptor-like serine/threonine kinase subfamily that includes members involved in plant development and defence. NIK was first identified by its capacity to interact with the geminivirus nuclear shuttle protein (NSP) and has been strongly associated with plant defence against geminivirus. Recent studies corroborate its function in transducing a defence signal against virus infection and describe components of the NIK-mediated antiviral signalling pathway. This mini-review describes the role of NIK as a transducer of a novel layer of plant innate defence, presents new data on NIK function, and discusses its possible involvement in plant development.