Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 286
Filtrar
1.
Plant Sci ; 312: 111036, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34620440

RESUMO

Like in mammals, the plant immune system has evolved to perceive damage. Damaged-associated molecular patterns (DAMPs) are endogenous signals generated in wounded or infected tissue after pathogen or insect attack. Although extracellular DNA (eDNA) is a DAMP signal that induces immune responses, plant responses after eDNA perception remain largely unknown. Here, we report that signaling defenses but not direct defense responses are induced after eDNA applications enhancing broad-range plant protection. A screening of defense signaling and hormone biosynthesis marker genes revealed that OXI1, CML37 and MPK3 are relevant eDNA-Induced Resistance markers (eDNA-IR). Additionally, we observed that eDNA from several Arabidopsis ecotypes and other phylogenetically distant plants such as citrus, bean and, more surprisingly, a monocotyledonous plant such as maize upregulates eDNA-IR marker genes. Using 3,3'-Diaminobenzidine (DAB) and aniline blue staining methods, we observed that H2O2 but not callose was strongly accumulated following self-eDNA treatments. Finally, eDNA resulted in effective induced resistance in Arabidopsis against the pathogens Hyaloperonospora arabidopsidis, Pseudomonas syringae, and Botrytis cinerea and against aphid infestation, reducing the number of nymphs and moving forms. Hence, the unspecificity of DNA origin and the wide range of insects to which eDNA can protect opens many questions about the mechanisms behind eDNA-IR.


Assuntos
Arabidopsis/genética , DNA/farmacologia , Resistência à Doença/genética , Resistência à Doença/imunologia , Imunidade Vegetal/genética , Transdução de Sinais/genética , Zea mays/genética , Arabidopsis/imunologia , Arabidopsis/microbiologia , Brassica/genética , Brassica/imunologia , Brassica/microbiologia , Citrus/genética , Citrus/imunologia , Citrus/microbiologia , Produtos Agrícolas/genética , Produtos Agrícolas/imunologia , Produtos Agrícolas/microbiologia , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Variação Genética , Genótipo , Phaseolus/genética , Phaseolus/imunologia , Phaseolus/microbiologia , Doenças das Plantas/genética , Doenças das Plantas/imunologia , Doenças das Plantas/microbiologia , Solanum/genética , Solanum/imunologia , Solanum/microbiologia , Spinacia oleracea/genética , Spinacia oleracea/imunologia , Spinacia oleracea/microbiologia , Zea mays/imunologia , Zea mays/microbiologia
2.
BMC Plant Biol ; 21(1): 216, 2021 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-33985439

RESUMO

BACKGROUND: The fungus Aspergillus flavus (A. flavus) is a serious threat to maize (Zea mays) production worldwide. It causes considerable yield and economic losses, and poses a health risk to humans and livestock due to the high toxicity of aflatoxin. However, key genes and regulatory networks conferring maize resistance to A. flavus are not clear, especially at the early stage of infection. Here, we performed a comprehensive transcriptome analysis of two maize inbred lines with contrasting resistance to A. flavus infection. RESULTS: The pairwise comparisons between mock and infected kernels in each line during the first 6 h post inoculation (hpi) showed that maize resistance to A. flavus infection was specific to the genotype and infection stage, and defense pathways were strengthened in the resistant line. Further comparison of the two maize lines revealed that the infection-induced up-regulated differentially expressed genes (DEGs) in the resistant line might underlie the enhanced resistance. Gene co-expression network analysis by WGCNA (weighted gene co-expression network analysis) identified 7 modules that were significantly associated with different infection stages, and 110 hub genes of these modules. These key regulators mainly participate in the biosynthesis of fatty acid and antibiotics. In addition, 90 candidate genes for maize resistance to A. flavus infection and/or aflatoxin contamination obtained in previous studies were confirmed to be differentially expressed between the resistant and susceptible lines within the first 6 hpi. CONCLUSION: This work unveiled more A. flavus resistance genes and provided a detailed regulatory network of early-stage resistance to A. flavus in maize.


Assuntos
Aspergillus flavus/patogenicidade , Resistência à Doença/genética , Resistência à Doença/imunologia , Doenças das Plantas/genética , Doenças das Plantas/imunologia , Zea mays/genética , Zea mays/imunologia , Produtos Agrícolas/genética , Produtos Agrícolas/imunologia , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Variação Genética , Genótipo , Interações Hospedeiro-Patógeno
3.
Mol Plant Pathol ; 22(6): 694-709, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33825303

RESUMO

The plant hypersensitive response (HR), a rapid cell death at the point of pathogenesis, is mediated by nucleotide-binding site, leucine-rich repeat (NLR) resistance proteins (R-proteins) that recognize the presence of specific pathogen-derived proteins. Rp1-D21 is an autoactive maize NLR R-protein that triggers HR spontaneously. We previously mapped loci associated with variation in the strength of HR induced by Rp1-D21. Here we identify the E3 ligase ZmMIEL1 as the causal gene at a chromosome 10 modifier locus. Transient ZmMIEL1 expression in Nicotiana benthamiana reduced HR induced by Rp1-D21, while suppression of ZmMIEL1 expression in maize carrying Rp1-D21 increased HR. ZmMIEL1 also suppressed HR induced by another autoactive NLR, the Arabidopsis R-protein RPM1D505V, in N. benthamiana. We demonstrated that ZmMIEL1 is a functional E3 ligase and that the effect of ZmMIEL1 was dependent on the proteasome but also that levels of Rp1-D21 and RPM1D505V were not reduced when coexpressed with ZmMIEL1 in the N. benthamiana system. By comparison to a similar system in Arabidopsis, we identify ZmMYB83 as a potential target of ZmMIEL1. Suppression of ZmMYB83 expression in maize lines carrying Rp1-D21 suppressed HR. Suppression of ZmMIEL1 expression caused an increase in ZmMYB83 transcript and protein levels in N. benthamiana and maize. Using coimmunoprecipitation and bimolecular fluorescence complementation assays, we demonstrated that ZmMIEL1 and ZmMYB83 physically interacted. Additionally, ZmMYB83 and ZmMIEL1 regulated the expression of a set of maize very long chain fatty acid (VLCFA) biosynthetic genes that may be involved in regulating HR.


Assuntos
Resistência à Doença , Doenças das Plantas/imunologia , Complexo de Endopeptidases do Proteassoma , Fatores de Transcrição/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Zea mays/genética , Morte Celular , Genes Reporter , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Filogenia , Folhas de Planta/enzimologia , Folhas de Planta/genética , Folhas de Planta/imunologia , Folhas de Planta/fisiologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Tabaco/genética , Tabaco/fisiologia , Fatores de Transcrição/genética , Ubiquitina-Proteína Ligases/genética , Zea mays/enzimologia , Zea mays/imunologia , Zea mays/fisiologia
4.
Mol Plant Pathol ; 22(5): 564-579, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33675291

RESUMO

Most plant intracellular immune receptors belong to nucleotide-binding, leucine-rich repeat (NLR) proteins. The recognition between NLRs and their corresponding pathogen effectors often triggers a hypersensitive response (HR) at the pathogen infection sites. The nicotinate N-methyltransferase (NANMT) is responsible for the conversion of nicotinate to trigonelline in plants. However, the role of NANMT in plant defence response is unknown. In this study, we demonstrated that the maize ZmNANMT, but not its close homolog ZmCOMT, an enzyme in the lignin biosynthesis pathway, suppresses the HR mediated by the autoactive NLR protein Rp1-D21 and its N-terminal coiled-coil signalling domain (CCD21 ). ZmNANMT, but not ZmCOMT, interacts with CCD21 , and they form a complex with HCT1806 and CCoAOMT2, two key enzymes in lignin biosynthesis, which can also suppress the autoactive HR mediated by Rp1-D21. ZmNANMT is mainly localized in the cytoplasm and nucleus, and either localization is important for suppressing the HR phenotype. These results lay the foundation for further elucidating the molecular mechanism of NANMTs in plant disease resistance.


Assuntos
Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Metiltransferases/metabolismo , Proteínas NLR/metabolismo , Doenças das Plantas/imunologia , Proteínas de Plantas/metabolismo , Transdução de Sinais , Zea mays/imunologia , Citoplasma/metabolismo , Resistência à Doença , Peptídeos e Proteínas de Sinalização Intracelular/genética , Metiltransferases/genética , Proteínas NLR/genética , Fenótipo , Filogenia , Imunidade Vegetal , Proteínas de Plantas/genética , Zea mays/genética
5.
Plant J ; 106(2): 526-535, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33533097

RESUMO

Northern corn leaf blight, caused by the fungal pathogen Setosphaeria turcica (anamorph Exserohilum turcicum), is one of the most devastating foliar diseases of maize (Zea mays). Four genes Ht1, Ht2, Ht3 and Htn1 represent the major sources of genetic resistance against the hemibiotrophic fungus S. turcica. Differential maize lines containing these genes also form the basis to classify S. turcica races. Here, we show that Ht2 and Ht3 are identical and allelic to the previously cloned Htn1 gene. Using a map-based cloning approach and Targeting Induced Local Lesions in Genomes (TILLING), we demonstrate that Ht2/Ht3 is an allele of the wall-associated receptor-like kinase gene ZmWAK-RLK1. The ZmWAK-RLK1 variants encoded by Htn1 and Ht2/Ht3 differ by multiple amino acid polymorphisms that particularly affect the putative extracellular domain. A diversity analysis in maize revealed the presence of dozens of ZmWAK-RLK1 alleles. Ht2, Ht3 and Htn1 have been described over decades as independent resistance loci with different race spectra and resistance responses. Our work demonstrates that these three genes are allelic, which has major implications for northern corn leaf blight resistance breeding and nomenclature of S. turcica pathotypes. We hypothesize that genetic background effects have confounded the classical description of these disease resistance genes in the past.


Assuntos
Ascomicetos , Resistência à Doença/genética , Genes de Plantas/genética , Doenças das Plantas/imunologia , Folhas de Planta/imunologia , Zea mays/imunologia , Alelos , Ascomicetos/imunologia , Mapeamento Cromossômico , Fosfotransferases/genética , Fosfotransferases/fisiologia , Doenças das Plantas/microbiologia , Folhas de Planta/genética , Folhas de Planta/microbiologia , Proteínas de Plantas/genética , Proteínas de Plantas/fisiologia , Zea mays/genética , Zea mays/microbiologia
6.
Plant Sci ; 304: 110811, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33568308

RESUMO

Maize (Zea mays L.) production is severely affected by northern corn leaf blight (NCLB), which is a destructive foliar disease caused by Setosphaeria turcica. In recent years, studies on the interaction between maize and S. turcica have been focused at the transcription level, with no research yet at the protein level. Here, we applied tandem mass tag labelling and liquid chromatography-tandem mass spectrometry to investigate the proteomes of maize leaves at 24 h and 72 h post-inoculation (hpi) with S. turcica. In total, 4740 proteins encoded by 4711 genes were quantified in this study. Clustering analyses provided an understanding of the dynamic reprogramming of leaves proteomes by revealing the functions of different proteins during S. turcica infection. Screening and classification of differentially expressed proteins (DEPs) revealed that numerous defense-related proteins, including defense marker proteins and proteins related to the phenylpropanoid lignin biosynthesis, benzoxazine biosynthesis and the jasmonic acid signalling pathway, participated in the defense responses of maize to S. turcica infection. Furthermore, the earlier induction of GST family proteins contributed to the resistance to S. turcica. In addition, the protein-protein interaction network of DEPs suggests that some defense-related proteins, for example, ZmGEB1, a hub node, play key roles in defense responses against S. turcica infection. Our study findings provide insight into the complex responses triggered by S. turcica at the protein level and lay the foundation for studying the interaction process between maize and S. turcica infection.


Assuntos
Ascomicetos , Doenças das Plantas/microbiologia , Zea mays/microbiologia , Ciclopentanos/metabolismo , Cromatografia Gasosa-Espectrometria de Massas , Glutationa Transferase/metabolismo , Redes e Vias Metabólicas , Oxilipinas/metabolismo , Doenças das Plantas/imunologia , Reguladores de Crescimento de Plantas/metabolismo , Folhas de Planta/imunologia , Folhas de Planta/metabolismo , Folhas de Planta/microbiologia , Proteínas de Plantas/metabolismo , Mapas de Interação de Proteínas , Proteômica , Transcriptoma , Zea mays/imunologia , Zea mays/metabolismo
7.
Int J Mol Sci ; 22(2)2021 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-33467172

RESUMO

Gibberella stalk rot (GSR) by Fusarium graminearum causes significant losses of maize production worldwide. Jasmonates (JAs) have been broadly known in regulating defense against pathogens through the homeostasis of active JAs and COI-JAZ-MYC function module. However, the functions of different molecular species of JAs and COI-JAZ-MYC module in maize interactions with Fusarium graminearum and regulation of diverse metabolites remain unknown. In this study, we found that exogenous application of MeJA strongly enhanced resistance to GSR. RNA-seq analysis showed that MeJA activated multiple genes in JA pathways, which prompted us to perform a genome-wide screening of key JA signaling components in maize. Yeast Two-Hybrid, Split-Luciferase, and Pull-down assays revealed that the JA functional and structural mimic coronatine (COR) functions as an essential ligand to trigger the interaction between ZmCOIa and ZmJAZ15. By deploying CRISPR-cas9 knockout and Mutator insertional mutants, we demonstrated that coi1a mutant is more resistant, whereas jaz15 mutant is more susceptible to GSR. Moreover, JA-deficient opr7-5opr8-2 mutant displayed enhanced resistance to GSR compared to wild type. Together, these results provide strong evidence that ZmJAZ15 plays a pivotal role, whereas ZmCOIa and endogenous JA itself might function as susceptibility factors, in maize immunity to GSR.


Assuntos
Ciclopentanos/metabolismo , Oxilipinas/metabolismo , Imunidade Vegetal , Zea mays/genética , Fusarium/patogenicidade , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Transdução de Sinais , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Zea mays/imunologia , Zea mays/microbiologia
8.
Theor Appl Genet ; 134(3): 941-958, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33388884

RESUMO

KEY MESSAGE: Genome-wide association revealed that resistance to Striga hermonthica is influenced by multiple genomic regions with moderate effects. It is possible to increase genetic gains from selection for Striga resistance using genomic prediction. Striga hermonthica (Del.) Benth., commonly known as the purple witchweed or giant witchweed, is a serious problem for maize-dependent smallholder farmers in sub-Saharan Africa. Breeding for Striga resistance in maize is complicated due to limited genetic variation, complexity of resistance and challenges with phenotyping. This study was conducted to (i) evaluate a set of diverse tropical maize lines for their responses to Striga under artificial infestation in three environments in Kenya; (ii) detect quantitative trait loci associated with Striga resistance through genome-wide association study (GWAS); and (iii) evaluate the effectiveness of genomic prediction (GP) of Striga-related traits. An association mapping panel of 380 inbred lines was evaluated in three environments under artificial Striga infestation in replicated trials and genotyped with 278,810 single-nucleotide polymorphism (SNP) markers. Genotypic and genotype x environment variations were significant for measured traits associated with Striga resistance. Heritability estimates were moderate (0.42) to high (0.92) for measured traits. GWAS revealed 57 SNPs significantly associated with Striga resistance indicator traits and grain yield (GY) under artificial Striga infestation with low to moderate effect. A set of 32 candidate genes physically near the significant SNPs with roles in plant defense against biotic stresses were identified. GP with different cross-validations revealed that prediction of performance of lines in new environments is better than prediction of performance of new lines for all traits. Predictions across environments revealed high accuracy for all the traits, while inclusion of GWAS-detected SNPs led to slight increase in the accuracy. The item-based collaborative filtering approach that incorporates related traits evaluated in different environments to predict GY and Striga-related traits outperformed GP for Striga resistance indicator traits. The results demonstrated the polygenic nature of resistance to S. hermonthica, and that implementation of GP in Striga resistance breeding could potentially aid in increasing genetic gain for this important trait.


Assuntos
Resistência à Doença/genética , Melhoramento Vegetal , Doenças das Plantas/genética , Plantas Daninhas/fisiologia , Polimorfismo de Nucleotídeo Único , Locos de Características Quantitativas , Striga/fisiologia , Zea mays/genética , Alelos , Mapeamento Cromossômico/métodos , Cromossomos de Plantas/genética , Resistência à Doença/imunologia , Ligação Genética , Marcadores Genéticos , Estudo de Associação Genômica Ampla , Doenças das Plantas/parasitologia , Zea mays/imunologia , Zea mays/parasitologia
9.
Metabolomics ; 17(1): 6, 2021 01 05.
Artigo em Inglês | MEDLINE | ID: mdl-33400019

RESUMO

INTRODUCTION: Studies investigating crop resistance to abiotic and biotic stress have largely focused on plant responses to singular forms of stress and individual biochemical pathways that only partially represent stress responses. Thus, combined abiotic and biotic stress treatments and the global assessment of their elicited metabolic expression remains largely unexplored. In this study, we employed targeted and untargeted metabolomics to investigate the molecular responses of maize (Zea mays) to abiotic, biotic, and combinatorial stress. OBJECTIVE: We compared the inducible metabolomes of heat-stressed (abiotic) and C. heterostrophus-infected (biotic) maize and examined the effects of heat stress on the ability of maize to defend itself against C. heterostrophus. METHODS: Ultra-high-performance liquid chromatography-high-resolution mass spectrometry was performed on plants grown under control conditions (28 °C), heat stress (38 °C), Cochliobolus heterostrophus infection, or combinatorial stress [heat (38 °C) + C. heterostrophus infection]. RESULTS: Multivariate analyses revealed differential metabolite expression between heat stress, C. heterostrophus infection, and their respective controls. In combinatorial experiments, treatment with heat stress prior to fungal inoculation negatively impacted maize disease resistance against C. heterostrophus, and distinct metabolome separation between combinatorial stressed plants and the non-heat-stressed infected controls was observed. Targeted analysis revealed inducible primary and secondary metabolite responses to abiotic/biotic stress, and combinatorial experiments indicated that deficiency in the hydroxycinnamic acid, p-coumaric acid, may contribute to the heat-induced susceptibility of maize to C. heterostrophus. CONCLUSION: These findings demonstrate that abiotic stress can predispose crops to more severe disease symptoms, underlining the increasing need to investigate defense chemistry in plants under combinatorial stress.


Assuntos
Resposta ao Choque Térmico , Metaboloma , Metabolômica , Doenças das Plantas/imunologia , Zea mays/imunologia , Zea mays/metabolismo , Cromatografia Líquida de Alta Pressão , Interações Hospedeiro-Patógeno , Espectrometria de Massas , Metabolômica/métodos , Doenças das Plantas/microbiologia , Zea mays/microbiologia
10.
Theor Appl Genet ; 134(3): 793-805, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33274402

RESUMO

KEY MESSAGE: High genetic variation in two European maize landraces can be harnessed to improve Gibberella ear rot resistance by integrated genomic tools. Fusarium graminearum (Fg) causes Gibberella ear rot (GER) in maize leading to yield reduction and contamination of grains with several mycotoxins. This study aimed to elucidate the molecular basis of GER resistance among 500 doubled haploid lines derived from two European maize landraces, "Kemater Landmais Gelb" (KE) and "Petkuser Ferdinand Rot" (PE). The two landraces were analyzed individually using genome-wide association studies and genomic selection (GS). The lines were genotyped with a 600-k maize array and phenotyped for GER severity, days to silking, plant height, and seed-set in four environments using artificial infection with a highly aggressive Fg isolate. High genotypic variances and broad-sense heritabilities were found for all traits. Genotype-environment interaction was important throughout. The phenotypic (r) and genotypic ([Formula: see text]) correlations between GER severity and three agronomic traits were low (r = - 0.27 to 0.20; [Formula: see text]= - 0.32 to 0.22). For GER severity, eight QTLs were detected in KE jointly explaining 34% of the genetic variance. In PE, no significant QTLs for GER severity were detected. No common QTLs were found between GER severity and the three agronomic traits. The mean prediction accuracies ([Formula: see text]) of weighted GS (wRR-BLUP) were higher than [Formula: see text] of marker-assisted selection (MAS) and unweighted GS (RR-BLUP) for GER severity. Using KE as the training set and PE as the validation set resulted in very low [Formula: see text] that could be improved by using fixed marker effects in the GS model.


Assuntos
Cromossomos de Plantas/genética , Resistência à Doença/genética , Variação Genética , Gibberella/fisiologia , Doenças das Plantas/genética , Zea mays/genética , Mapeamento Cromossômico , Resistência à Doença/imunologia , Marcadores Genéticos , Fenótipo , Doenças das Plantas/microbiologia , Locos de Características Quantitativas , Zea mays/imunologia , Zea mays/microbiologia
11.
Int J Mol Sci ; 21(21)2020 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-33153030

RESUMO

Ostrinia furnacalis, is the major pest of maize causing significant yield losses. So far, many approaches have been used to increase the virulence of entomopathogenic fungal isolates. The current study is an attempt to estimate synergistic effect of Beauveria bassiana and Trichoderma asperellum in order to explore larval immune response through RNA sequencing and differentially expression analysis. In vivo synergism was examined in seven proportions (B. bassiana: T. asperellum = 1:1, 1:2, 1:3, 1:4, 4:1, 3:1, 2:1) and in the in vitro case, two inoculation methods were applied: seed coating and soil drenching. Results revealed significant decrease in plant damage and high larval mortality in fungal treatments. Fungal isolates mediated the plant defense by increasing proline, superoxide dismutase (SOD), peroxidase (POD), polyphenol oxidase (PPO) and protease activities. Seed coating method was proved to be the most effective in case of maize endophytic colonization. In total, 59 immune-related differentially expressed genes DEGs were identified including, cytochrome P450, heat shock protein, ABC transporter, cadherin, peptidoglycan recognition protein (PGRP), cuticlular protein, etc. Further, transcriptomic response was confirmed by qRT-PCR. Our results concluded that, coculture of B. bassiana and T. asperellum has the synergistic potential to suppress the immune response of O. furnacalis and can be used as sustainable approach to induce plant resistance through activation of defense-related enzymes.


Assuntos
Beauveria/fisiologia , Hypocreales/fisiologia , Imunidade/fisiologia , Mariposas/imunologia , Zea mays/imunologia , Zea mays/parasitologia , Animais , Resistência à Doença/genética , Resistência à Doença/fisiologia , Perfilação da Expressão Gênica , Imunidade/genética , Larva/genética , Larva/imunologia , Larva/microbiologia , Mariposas/genética , Mariposas/microbiologia , Mariposas/patogenicidade , Controle Biológico de Vetores/métodos , Análise de Sequência de RNA , Transcriptoma , Zea mays/genética , Zea mays/microbiologia
12.
Nat Plants ; 6(11): 1375-1388, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-33106639

RESUMO

Specialized metabolites constitute key layers of immunity that underlie disease resistance in crops; however, challenges in resolving pathways limit our understanding of the functions and applications of these metabolites. In maize (Zea mays), the inducible accumulation of acidic terpenoids is increasingly considered to be a defence mechanism that contributes to disease resistance. Here, to understand maize antibiotic biosynthesis, we integrated association mapping, pan-genome multi-omic correlations, enzyme structure-function studies and targeted mutagenesis. We define ten genes in three zealexin (Zx) gene clusters that encode four sesquiterpene synthases and six cytochrome P450 proteins that collectively drive the production of diverse antibiotic cocktails. Quadruple mutants in which the ability to produce zealexins (ZXs) is blocked exhibit a broad-spectrum loss of disease resistance. Genetic redundancies ensuring pathway resiliency to single null mutations are combined with enzyme substrate promiscuity, creating a biosynthetic hourglass pathway that uses diverse substrates and in vivo combinatorial chemistry to yield complex antibiotic blends. The elucidated genetic basis of biochemical phenotypes that underlie disease resistance demonstrates a predominant maize defence pathway and informs innovative strategies for transferring chemical immunity between crops.


Assuntos
Antibacterianos/biossíntese , Resistência à Doença/genética , Imunidade Inata/genética , Redes e Vias Metabólicas/genética , Zea mays/genética , Resistência à Doença/fisiologia , Perfilação da Expressão Gênica , Genes de Plantas/genética , Genes de Plantas/fisiologia , Metabolômica , Família Multigênica/genética , Família Multigênica/fisiologia , Proteômica , Zea mays/imunologia , Zea mays/metabolismo , Zea mays/microbiologia
13.
Plant J ; 104(6): 1582-1602, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33058410

RESUMO

Plant elicitor peptides (Peps) are conserved regulators of defense responses and models for the study of damage-associated molecular pattern-induced immunity. Although present as multigene families in most species, the functional relevance of these multigene families remains largely undefined. While Arabidopsis Peps appear largely redundant in function, previous work examining Pep-induced responses in maize (Zm) implied specificity of function. To better define the function of individual ZmPeps and their cognate receptors (ZmPEPRs), activities were examined by assessing changes in defense-associated phytohormones, specialized metabolites and global gene expression patterns, in combination with heterologous expression assays and analyses of CRISPR/Cas9-generated knockout plants. Beyond simply delineating individual ZmPep and ZmPEPR activities, these experiments led to a number of new insights into Pep signaling mechanisms. ZmPROPEP and other poaceous precursors were found to contain multiple active Peps, a phenomenon not previously observed for this family. In all, seven new ZmPeps were identified and the peptides were found to have specific activities defined by the relative magnitude of their response output rather than by uniqueness. A striking correlation was observed between individual ZmPep-elicited changes in levels of jasmonic acid and ethylene and the magnitude of induced defense responses, indicating that ZmPeps may collectively regulate immune output through rheostat-like tuning of phytohormone levels. Peptide structure-function studies and ligand-receptor modeling revealed structural features critical to the function of ZmPeps and led to the identification of ZmPep5a as a potential antagonist peptide able to competitively inhibit the activity of other ZmPeps, a regulatory mechanism not previously observed for this family.


Assuntos
Peptídeos/fisiologia , Defesa das Plantas contra Herbivoria , Zea mays/fisiologia , Proteína 9 Associada à CRISPR , Sistemas CRISPR-Cas , Edição de Genes , Regulação da Expressão Gênica de Plantas , Técnicas de Inativação de Genes , Genes de Plantas/genética , Peptídeos/metabolismo , Filogenia , Reguladores de Crescimento de Plantas/metabolismo , Reguladores de Crescimento de Plantas/fisiologia , Receptores de Peptídeos/genética , Receptores de Peptídeos/metabolismo , Receptores de Peptídeos/fisiologia , Zea mays/genética , Zea mays/imunologia , Zea mays/metabolismo
14.
Mol Plant Pathol ; 21(12): 1662-1676, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33037769

RESUMO

Plant disease resistance proteins (R-proteins) detect specific pathogen-derived molecules, triggering a defence response often including a rapid localized cell death at the point of pathogen penetration called the hypersensitive response (HR). The maize Rp1-D21 gene encodes a protein that triggers a spontaneous HR causing spots on leaves in the absence of any pathogen. Previously, we used fine mapping and functional analysis in a Nicotiana benthamiana transient expression system to identify and characterize a number of genes associated with variation in Rp1-D21-induced HR. Here we describe a system for characterizing genes mediating HR, using virus-induced gene silencing (VIGS) in a maize line carrying Rp1-D21. We assess the roles of 12 candidate genes. Three of these genes, SGT1, RAR1, and HSP90, are required for HR induced by a number of R-proteins across several plant-pathogen systems. We confirmed that maize HSP90 was required for full Rp1-D21-induced HR. However, suppression of SGT1 expression unexpectedly increased the severity of Rp1-D21-induced HR while suppression of RAR1 expression had no measurable effect. We confirmed the effects on HR of two genes we had previously validated in the N. benthamiana system, hydroxycinnamoyltransferase and caffeoyl CoA O-methyltransferase. We further showed the suppression the expression of two previously uncharacterized, candidate genes, IQ calmodulin binding protein (IQM3) and vacuolar protein sorting protein 37, suppressed Rp1-D21-induced HR. This approach is an efficient way to characterize the roles of genes modulating the hypersensitive defence response and other dominant lesion phenotypes in maize.


Assuntos
Inativação Gênica , Doenças das Plantas/imunologia , Proteínas de Plantas/metabolismo , Tabaco/genética , Zea mays/genética , Aciltransferases/genética , Aciltransferases/metabolismo , Morte Celular , Resistência à Doença , Metiltransferases/genética , Metiltransferases/metabolismo , Fenótipo , Doenças das Plantas/virologia , Imunidade Vegetal , Folhas de Planta/genética , Folhas de Planta/imunologia , Folhas de Planta/virologia , Proteínas de Plantas/genética , Ligação Proteica , Tabaco/imunologia , Tabaco/virologia , Zea mays/imunologia , Zea mays/virologia
15.
Int J Mol Sci ; 21(18)2020 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-32899999

RESUMO

Common rust (CR) caused by Puccina sorghi is one of the destructive fungal foliar diseases of maize and has been reported to cause moderate to high yield losses. Providing CR resistant germplasm has the potential to increase yields. To dissect the genetic architecture of CR resistance in maize, association mapping, in conjunction with linkage mapping, joint linkage association mapping (JLAM), and genomic prediction (GP) was conducted on an association-mapping panel and five F3 biparental populations using genotyping-by-sequencing (GBS) single-nucleotide polymorphisms (SNPs). Analysis of variance for the biparental populations and the association panel showed significant genotypic and genotype x environment (GXE) interaction variances except for GXE of Pop4. Heritability (h2) estimates were moderate with 0.37-0.45 for the individual F3 populations, 0.45 across five populations and 0.65 for the association panel. Genome-wide association study (GWAS) analyses revealed 14 significant marker-trait associations which individually explained 6-10% of the total phenotypic variances. Individual population-based linkage analysis revealed 26 QTLs associated with CR resistance and together explained 14-40% of the total phenotypic variances. Linkage mapping revealed seven QTLs in pop1, nine QTL in pop2, four QTL in pop3, five QTL in pop4, and one QTL in pop5, distributed on all chromosomes except chromosome 10. JLAM for the 921 F3 families from five populations detected 18 QTLs distributed in all chromosomes except on chromosome 8. These QTLs individually explained 0.3 to 3.1% and together explained 45% of the total phenotypic variance. Among the 18 QTL detected through JLAM, six QTLs, qCR1-78, qCR1-227, qCR3-172, qCR3-186, qCR4-171, and qCR7-137 were also detected in linkage mapping. GP within population revealed low to moderate correlations with a range from 0.19 to 0.51. Prediction correlation was high with r = 0.78 for combined analysis of the five F3 populations. Prediction of biparental populations by using association panel as training set reveals positive correlations ranging from 0.05 to 0.22, which encourages to develop an independent but related population as a training set which can be used to predict diverse but related populations. The findings of this study provide valuable information on understanding the genetic basis of CR resistance and the obtained information can be used for developing functional molecular markers for marker-assisted selection and for implementing GP to improve CR resistance in tropical maize.


Assuntos
Resistência à Doença/genética , Doenças das Plantas , Puccinia , Zea mays/genética , Zea mays/microbiologia , Mapeamento Cromossômico , Cromossomos de Plantas , Biologia Computacional , Ligação Genética , Estudo de Associação Genômica Ampla , Genômica/métodos , Genótipo , Fenótipo , Doenças das Plantas/genética , Doenças das Plantas/imunologia , Doenças das Plantas/microbiologia , Polimorfismo de Nucleotídeo Único , Puccinia/imunologia , Puccinia/patogenicidade , Locos de Características Quantitativas , Sementes/genética , Sementes/microbiologia , Clima Tropical , Zea mays/imunologia
16.
Proc Natl Acad Sci U S A ; 117(31): 18385-18392, 2020 08 04.
Artigo em Inglês | MEDLINE | ID: mdl-32690686

RESUMO

Transgenic crops that produce insecticidal proteins from Bacillus thuringiensis (Bt) can suppress pests and reduce insecticide sprays, but their efficacy is reduced when pests evolve resistance. Although farmers plant refuges of non-Bt host plants to delay pest resistance, this tactic has not been sufficient against the western corn rootworm, Diabrotica virgifera virgifera In the United States, some populations of this devastating pest have rapidly evolved practical resistance to Cry3 toxins and Cry34/35Ab, the only Bt toxins in commercially available corn that kill rootworms. Here, we analyzed data from 2011 to 2016 on Bt corn fields producing Cry3Bb alone that were severely damaged by this pest in 25 crop-reporting districts of Illinois, Iowa, and Minnesota. The annual mean frequency of these problem fields was 29 fields (range 7 to 70) per million acres of Cry3Bb corn in 2011 to 2013, with a cost of $163 to $227 per damaged acre. The frequency of problem fields declined by 92% in 2014 to 2016 relative to 2011 to 2013 and was negatively associated with rotation of corn with soybean. The effectiveness of corn rotation for mitigating Bt resistance problems did not differ significantly between crop-reporting districts with versus without prevalent rotation-resistant rootworm populations. In some analyses, the frequency of problem fields was positively associated with planting of Cry3 corn and negatively associated with planting of Bt corn producing both a Cry3 toxin and Cry34/35Ab. The results highlight the central role of crop rotation for mitigating impacts of D. v. virgifera resistance to Bt corn.


Assuntos
Besouros/fisiologia , Produção Agrícola/métodos , Endotoxinas/farmacologia , Doenças das Plantas/parasitologia , Plantas Geneticamente Modificadas/imunologia , Zea mays/imunologia , Animais , Bacillus thuringiensis/genética , Bacillus thuringiensis/metabolismo , Besouros/efeitos dos fármacos , Produção Agrícola/economia , Endotoxinas/genética , Endotoxinas/metabolismo , Resistência a Inseticidas , Iowa , Controle Biológico de Vetores/economia , Doenças das Plantas/economia , Doenças das Plantas/imunologia , Doenças das Plantas/prevenção & controle , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/parasitologia , Soja/crescimento & desenvolvimento , Zea mays/genética , Zea mays/crescimento & desenvolvimento , Zea mays/parasitologia
17.
Genomics Proteomics Bioinformatics ; 18(3): 241-255, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32531477

RESUMO

Fusarium ear rot (FER) caused by Fusarium verticillioides is one of the most common diseases affecting maize production worldwide. FER results in severe yield losses and grain contamination with health-threatening mycotoxins. Although most studies to date have focused on comprehensive analysis of gene regulation in maize during defense responses against F. verticillioides infection, less is known about the role of microRNAs (miRNAs) in this process. We used deep sequencing to compare small RNA libraries from the maize kernels of susceptible (N6) or resistant (BT-1) inbred lines from uninfected plants and upon F. verticillioides infection. We found that pathogen exposure was accompanied by dynamic alterations in expression levels of multiple miRNAs, including new members of previously annotated miRNA families. A combination of transcriptomic, degradomic, and bioinformatics analyses revealed that F. verticillioides-responsive miRNAs and their potential target genes displayed opposite expression patterns in the susceptible and resistant genotypes. Functional category analysis uncovered preferential enrichment of the pathogen-responsive miRNAs and their targets in the phenylpropanoid metabolic processes, plant-pathogen interactions, and plant phytohormone signal transduction pathways. Furthermore, transgenic maize plants overexpressing miR408b exhibited reduced resistance to F. verticillioides infection in a susceptible maize line. These findings provide new insights into the regulatory roles of miRNAs in maize immunity against FER and new resources for breeding disease resistance into maize.


Assuntos
Fusarium/patogenicidade , Regulação da Expressão Gênica de Plantas , Interações Hospedeiro-Patógeno/imunologia , MicroRNAs/genética , Doenças das Plantas/imunologia , Transcriptoma , Zea mays/imunologia , Fusarium/genética , Interações Hospedeiro-Patógeno/genética , MicroRNAs/metabolismo , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Zea mays/genética , Zea mays/microbiologia
18.
BMC Plant Biol ; 20(1): 206, 2020 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-32393173

RESUMO

BACKGROUND: Fungus infection in staple grains affects the food storage and threatens food security. The Aspergillus flavus is known to infect multiple grains and produce mycotoxin Aflatoxin B1, which is mutagenic, teratogenic and causes immunosuppression in animals. However, the molecular mechanism of maize resistance to A. flavus is largely unknown. RESULTS: Here we used corn kernels to investigate resistance genes to A. flavus using genome-wide association study (GWAS) of 313 inbred lines. We characterized the resistance levels of kernels after inoculating with A. flavus. The GWAS with 558,529 SNPs identified four associated loci involving 29 candidate genes that were linked to seed development, resistance or infection, and involved in signal pathways, seed development, germination, dormancy, epigenetic modification, and antimicrobial activity. In addition, a few candidate genes were also associated with several G-protein signaling and phytohormones that might involve in synergistic work conferring different resistance during seed development. Expression of 16 genes out of 29 during kernel development was also associated with resistance levels. CONCLUSIONS: We characterized the resistance levels of 313 maize kernels after inoculating with A. flavus, and found four associated loci and 16 candidate maize genes. The expressed 16 genes involved in kernel structure and kernel composition most likely contribute to mature maize kernels' resistance to A. flavus, and in particular, in the development of pericarp. The linked candidate genes could be experimentally transformed to validate and manipulate fungal resistance. Thus this result adds value to maize kernels in breeding programs.


Assuntos
Aspergillus flavus/fisiologia , Resistência à Doença/genética , Estudo de Associação Genômica Ampla , Doenças das Plantas/imunologia , Zea mays/genética , Doenças das Plantas/microbiologia , Sementes/genética , Sementes/imunologia , Sementes/microbiologia , Zea mays/imunologia , Zea mays/microbiologia
19.
BMC Plant Biol ; 20(1): 203, 2020 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-32393176

RESUMO

BACKGROUND: Striga hermonthica (Benth.) parasitism militates against increased maize production and productivity in savannas of sub-Saharan Africa (SSA). Identification of Striga resistance genes is important in developing genotypes with durable resistance. So far, there is only one report on the existence of QTL for Striga resistance on chromosome 6 of maize. The objective of this study was to identify genomic regions significantly associated with grain yield and other agronomic traits under artificial Striga field infestation. A panel of 132 early-maturing maize inbreds were phenotyped for key agronomic traits under Striga-infested and Striga-free conditions. The inbred lines were also genotyped using 47,440 DArTseq markers from which 7224 markers were retained for population structure analysis and genome-wide association study (GWAS). RESULTS: The inbred lines were grouped into two major clusters based on structure analysis as well as the neighbor-joining hierarchical clustering. A total of 24 SNPs significantly associated with grain yield, Striga damage at 8 and 10 weeks after planting (WAP), ears per plant and ear aspect under Striga infestation were detected. Under Striga-free conditions, 11 SNPs significantly associated with grain yield, number of ears per plant and ear aspect were identified. Three markers physically located close to the putative genes GRMZM2G164743 (bin 10.05), GRMZM2G060216 (bin 3.06) and GRMZM2G103085 (bin 5.07) were detected, linked to grain yield, Striga damage at 8 and 10 WAP and number of ears per plant under Striga infestation, explaining 9 to 42% of the phenotypic variance. Furthermore, the S9_154,978,426 locus on chromosome 9 was found at 2.61 Mb close to the ZmCCD1 gene known to be associated with the reduction of strigolactone production in the maize roots. CONCLUSIONS: Presented in this study is the first report of the identification of significant loci on chromosomes 9 and 10 of maize that are closely linked to ZmCCD1 and amt5 genes, respectively and may be related to plant defense mechanisms against Striga parasitism. After validation, the identified loci could be targets for breeders for marker-assisted selection (MAS) to accelerate genetic enhancement of maize for Striga resistance in the tropics, particularly in SSA, where the parasitic weed is endemic.


Assuntos
Resistência à Doença/genética , Genoma de Planta/genética , Estudo de Associação Genômica Ampla , Doenças das Plantas/imunologia , Striga/fisiologia , Zea mays/genética , Grão Comestível , Loci Gênicos , Genótipo , Fenótipo , Doenças das Plantas/parasitologia , Polimorfismo de Nucleotídeo Único/genética , Zea mays/imunologia , Zea mays/parasitologia
20.
Plant J ; 103(1): 412-429, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32168401

RESUMO

The fungal genus Cochliobolus describes necrotrophic pathogens that give rise to significant losses on rice, wheat, and maize. Revealing plant mechanisms of non-host resistance (NHR) against Cochliobolus will help to uncover strategies that can be exploited in engineered cereals. Therefore, we developed a heterogeneous pathosystem and studied the ability of Cochliobolus to infect dicotyledons. We report here that C. miyabeanus and C. heterostrophus infect Arabidopsis accessions and produce functional conidia, thereby demonstrating the ability to accept Brassica spp. as host plants. Some ecotypes exhibited a high susceptibility, whereas others hindered the necrotrophic disease progression of the Cochliobolus strains. Natural variation in NHR among the tested Arabidopsis accessions can advance the identification of genetic loci that prime the plant's defence repertoire. We found that applied phytotoxin-containing conidial fluid extracts of C. miyabeanus caused necrotic lesions on rice leaves but provoked only minor irritations on Arabidopsis. This result implies that C. miyabeanus phytotoxins are insufficiently adapted to promote dicot colonization, which corresponds to a retarded infection progression. Previous studies on rice demonstrated that ethylene (ET) promotes C. miyabeanus infection, whereas salicylic acid (SA) and jasmonic acid (JA) exert a minor function. However, in Arabidopsis, we revealed that the genetic disruption of the ET and JA signalling pathways compromises basal resistance against Cochliobolus, whereas SA biosynthesis mutants showed a reduced susceptibility. Our results refer to the synergistic action of ET/JA and indicate distinct defence systems between Arabidopsis and rice to confine Cochliobolus propagation. Moreover, this heterogeneous pathosystem may help to reveal mechanisms of NHR and associated defensive genes against Cochliobolus infection.


Assuntos
Arabidopsis/imunologia , Ascomicetos , Resistência à Doença/fisiologia , Oryza/imunologia , Doenças das Plantas/microbiologia , Reguladores de Crescimento de Plantas/fisiologia , Zea mays/imunologia , Arabidopsis/microbiologia , Arabidopsis/fisiologia , Ciclopentanos/metabolismo , Suscetibilidade a Doenças , Etilenos/metabolismo , Oryza/microbiologia , Oryza/fisiologia , Oxilipinas/metabolismo , Doenças das Plantas/imunologia , Ácido Salicílico/metabolismo , Zea mays/microbiologia , Zea mays/fisiologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...