Transcriptional and Metabolic Changes Associated to the Infection by Fusarium verticillioides in Maize Inbreds with Contrasting Ear Rot Resistance

Fusarium verticillioides causes ear rot and grain mycotoxins in maize (Zea mays L.), which are harmful to human and animal health. Breeding and growing less susceptible plant genotypes is one alternative to reduce these detrimental effects. A better understanding of the resistance mechanisms would facilitate the implementation of strategic molecular agriculture to breeding of resistant germplasm. Our aim was to identify genes and metabolites that may be related to the Fusarium reaction in a resistant (L4637) and a susceptible (L4674) inbred. Gene expression data were obtained from microarray hybridizations in inoculated and non-inoculated kernels from both inbreds. Fungal inoculation did not produce considerable changes in gene expression and metabolites in L4637. Defense-related genes changed in L4674 kernels, responding specifically to the pathogen infection. These results indicate that L4637 resistance may be mainly due to constitutive defense mechanisms preventing fungal infection. These mechanisms seem to be poorly expressed in L4674; and despite the inoculation activate a defense response; this is not enough to prevent the disease progress in this susceptible line. Through this study, a global view of differential genes expressed and metabolites accumulated during resistance and susceptibility to F. verticillioides inoculation has been obtained, giving additional information about the mechanisms and pathways conferring resistance to this important disease in maize.Fil: Campos Bermudez, Valeria Alina. Consejo Nacional de Invest.cientif.y Tecnicas. Centro Cientifico Tecnol.conicet - Rosario. Centro de Est.fotosinteticos y Bioquimicos (i);Fil: Fauguel, Carolina María. Instituto Nacional de Tecnologia Agropecuaria. Centro Reg.buenos Aires Norte. Estacion Exptal.agrop.pergamino;Fil: Tronconi, Marcos Ariel. Consejo Nacional de Invest.cientif.y Tecnicas. Centro Cientifico Tecnol.conicet - Rosario. Centro de Est.fotosinteticos y Bioquimicos (i);Fil: Casati, Paula. Consejo Nacional de Invest.cientif.y Tecnicas. Centro Cientifico Tecnol.conicet - Rosario. Centro de Est.fotosinteticos y Bioquimicos (i);Fil: Presello, Daniel. Instituto Nacional de Tecnologia Agropecuaria. Centro Reg.buenos Aires Norte. Estacion Exptal.agrop.pergamino;Fil: Andreo, Carlos Santiago. Consejo Nacional de Invest.cientif.y Tecnicas. Centro Cientifico Tecnol.conicet - Rosario. Centro de Est.fotosinteticos y Bioquimicos (i)

Deciphering the number and location of active sites in the monomeric glyoxalase I of Zea mays

Detoxification of methylglyoxal, a toxic by-product of central sugar metabolism, is a major issue for all forms of life. The glyoxalase pathway evolved to effectively convert methylglyoxal into d-lactate via a glutathione hemithioacetal intermediate. Recently, we have shown that the monomeric glyoxalase I from maize exhibits a symmetric fold with two cavities, potentially harboring two active sites, in analogy with homodimeric enzyme surrogates. Here we confirm that only one of the two cavities exhibits glyoxalase I activity and show that it adopts a tunnel-shaped structure upon substrate binding. Such conformational change gives rise to independent binding sites for glutathione and methylglyoxal in the same active site, with important implications for the molecular reaction mechanism, which has been a matter of debate for several decades. Database: Structural data are available in The Protein Data Bank database under the accession numbers 6BNN, 6BNX, and 6BNZ.Fil: Gonzalez, Javier Marcelo. Universidad Nacional de Santiago del Estero. Instituto de Bionanotecnología del Noa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Bionanotecnología del Noa; ArgentinaFil: Agostini, Romina Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro de Estudios Fotosintéticos y Bioquímicos. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos; ArgentinaFil: Alvarez, Clarisa Ester. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro de Estudios Fotosintéticos y Bioquímicos. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos; ArgentinaFil: Klinke, Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Andreo, Carlos Santiago. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro de Estudios Fotosintéticos y Bioquímicos. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos; ArgentinaFil: Campos Bermudez, Valeria Alina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro de Estudios Fotosintéticos y Bioquímicos. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos; Argentin

Trichoderma root colonization in maize triggers epigenetic changes in genes related to the jasmonic and salicylic acid pathways that prime defenses against Colletotrichum graminicola leaf infection

Beneficial interactions between plant roots and Trichoderma species lead to both local and systemic enhancements of the plant immune system through a mechanism known as priming of defenses. Previously, we have reported a number of genes and proteins that are differentially regulated in distant tissues of maize plants following inoculation with Trichoderma atroviride. To further investigate the mechanisms involved in the systemic activation of plant responses, here we have further evaluated the regulatory aspects of a selected group of genes when priming is triggered in maize plants. Time-course experiments from the beginning of the interaction between T. atroviride and maize roots followed by leaf infection with Colletotrichum graminicola allowed us to identify a gene set regulated by priming in the leaf tissue. In the same experiment, phytohormone measurements revealed a decrease in jasmonic acid concentration while salicylic acid increased at 2 d and 6 d post-inoculation. In addition, chromatin structure and modification assays showed that chromatin was more open in the primed state compared with unprimed control conditions, and this allowed for quicker gene activation in response to pathogen attack. Overall, the results allowed us to gain insights on the interplay between the phytohormones and epigenetic regulatory events in the systemic and long-lasting regulation of maize plant defenses following Trichoderma inoculation.Fil: Agostini, Romina Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro de Estudios Fotosintéticos y Bioquímicos. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos; ArgentinaFil: Ariel, Federico Damian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; ArgentinaFil: Rius, Sebastian Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro de Estudios Fotosintéticos y Bioquímicos. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos; ArgentinaFil: Vargas, Walter Alberto. YPF - Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Campos Bermudez, Valeria Alina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro de Estudios Fotosintéticos y Bioquímicos. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos; Argentin

The identification of maize and Arabidopsis type I flavone synthases links flavones with hormones and biotic interactions

Flavones are a major group of flavonoids with diverse functions and extensively distributed in land plants. There are two different classes of flavone synthase (FNS) enzymes that catalyze the conversion of the flavanones into flavones. The FNSI class comprises soluble Fe2+/2-oxoglutarate-dependent dioxygenases, and FNSII enzymes are oxygen- and NADPH-dependent cytochrome P450 membrane-bound monooxygenases. Here, we describe the identification and characterization of two FNSI enzymes from Zea mays and Arabidopsis thaliana. In maize, ZmFNSI-1 is expressed at significantly higher levels in silks and pericarps expressing the 3-deoxy flavonoid R2R3-MYB regulator P1, suggesting that ZmFNSI-1 could be the main enzyme for the synthesis of flavone O-glycosides. We also show here that AtDMR6, the Arabidopsis homologous enzyme to ZmFNSI-1, has FNSI activity; dmr6 mutants show loss of susceptibility to Hyaloperonospora parasitica and other pathogens. AtDMR6 expression analysis showed a tissue and developmental stage-dependent pattern, with high expression in cauline and senescing leaves. Finally, we show that Arabidopsis cauline and senescing leaves accumulate apigenin, demonstrating that Arabidopsis thaliana plants have a FNSI activity involved in the biosynthesis of flavones. The results presented here also suggest a cross-talk between the flavone and salicylic acid pathways in Arabidopsis; in this way, pathogens would induce flavones to decrease salicylic acid and hence increase susceptibility.Fil: Falcone Ferreyra, María Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Centro de Estudios Fotosintéticos y Bioquímicos (i); ArgentinaFil: Emiliani, Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Centro de Estudios Fotosintéticos y Bioquímicos (i); ArgentinaFil: Rodriguez, Eduardo Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Campos Bermudez, Valeria Alina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Centro de Estudios Fotosintéticos y Bioquímicos (i); ArgentinaFil: Grotewold, Erich. Ohio State University; Estados UnidosFil: Casati, Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Centro de Estudios Fotosintéticos y Bioquímicos (i); Argentin

Volatile compounds released by maize grains and silks in response to infection by Fusarium verticillioides and its association with pathogen resistance

Many plants respond to fungal infections by producing and/or emitting a specific blend of oxylipins, some of them through the lipoxygenase (LOX) pathway. In vitro bioassays revealed that volatiles from silks and grains of a set of six maize genotypes with variable resistance to Fusarium verticillioides affected fungal growth in different ways. Analyses by solid phase microextraction and GC-MS showed different volatile profiles in silks and grains of each genotype. Susceptible genotypes with higher concentrations of precursor polyunsaturated fatty acids produced more volatiles, mainly C9 compounds, in comparison to moderately resistant ones. Real-time PCR from several lipoxygenase transcripts revealed that levels of gene expression depended on the genotype and the inoculation level and suggested that F. verticillioides could use compounds from the 9-LOX pathway to promote infection in grains. On the other hand, volatiles produced by the 13-LOX pathway were more important in moderately resistant genotypes and could be associated to field resistance. Results from this set of genotypes indicate that LOX-regulated volatile compounds might be important in F. verticillioides infection and should be targeted in further research to understand disease resistance.Fil: Fauguel, Carolina María. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Norte. Estación Experimental Agropecuaria Pergamino; ArgentinaFil: Campos Bermudez, Valeria Alina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro de Estudios Fotosintéticos y Bioquímicos. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos; ArgentinaFil: Iglesias, J.. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Norte. Estación Experimental Agropecuaria Pergamino; ArgentinaFil: Fernandez, M.. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Norte. Estación Experimental Agropecuaria Pergamino; ArgentinaFil: Farroni, A.. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Norte. Estación Experimental Agropecuaria Pergamino; ArgentinaFil: Andreo, Carlos Santiago. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro de Estudios Fotosintéticos y Bioquímicos. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos; ArgentinaFil: Presello, Daniel. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Norte. Estación Experimental Agropecuaria Pergamino; Argentin

Long-lasting primed state in maize plants: Salicylic acid and steroid signaling pathways as key players in the early activation of immune responses in silks

In the present study, we investigated the induced systemic resistance (ISR) activated by the beneficial fungus Trichoderma atroviride in maize plants, and the early immunological responses triggered after challenge with the ear rot pathogen Fusarium verticillioides. By transcriptional analysis, we were able to identify the gene core set specifically modulated in silks of maize plants expressing ISR. Our results showed that the main transcriptional reprogramming falls into genes involved in five main functional categories: cell structure or cell wall, amino acid and protein metabolism, stress responses, signaling, and transport. Among these ISR-related genes, it is important to highlight novel findings regarding hormone metabolism and signaling. The expression of hormone-dependent genes was in good agreement with the abscisic acid, jasmonic acid, and salicylic acid (SA) levels detected in the plants under study. The experimental design allowed the identification of novel regulatory elements related to a heightened state of defense in silks and suggests that steroids and SA are central components of a master regulatory network controlling the immunity of silks during ISR. The results presented also provide evidence about the molecular mechanisms used by maize silks against F. verticillioides to counteract pathogenic development and host invasion, including pathogenesis-related genes, plant cell-wall reinforcement, fungal cell-wall-degrading enzymes and secondary metabolism.Fil: Agostini, Romina Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro de Estudios Fotosintéticos y Bioquímicos. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos; ArgentinaFil: Postigo, Agustina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro de Estudios Fotosintéticos y Bioquímicos. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos; ArgentinaFil: Rius, Sebastian Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro de Estudios Fotosintéticos y Bioquímicos. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos; ArgentinaFil: Rech, Gabriel E.. Institut de Biologia Evolutiva; España. Consejo Superior de Investigaciones Científicas; España. Universitat Pompeu Fabra; EspañaFil: Campos Bermudez, Valeria Alina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro de Estudios Fotosintéticos y Bioquímicos. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos; ArgentinaFil: Vargas, Walter Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro de Estudios Fotosintéticos y Bioquímicos. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos; Argentin

A proposed reaction mechanism for maize monomeric glyoxalase I

Detoxification of methylglyoxal, a toxic by-product of central sugar metabolism, is a major issue for all forms of life. The glyoxalase pathway evolved to effectively convert methylglyoxal into D-lactate via a glutathione hemithioacetal intermediate. Recently, we have shown that the monomeric glyoxalase I from maize exhibits a symmetric fold with two cavities, potentially harboring two active sites, in analogy with homodimeric enzyme surrogates. Here we confirm that only one of the two cavities exhibits glyoxalase I activity and show that it adopts a tunnel-shaped structure upon substrate binding. Such conformational change gives rise to independent binding sites for glutathione and methylglyoxal in the same active site, with important implications for the molecular reaction mechanism, which has been a matter of debate for several decades.Fil: Gonzalez, Javier Marcelo. Universidad Nacional de Santiago del Estero. Instituto de Bionanotecnología del Noa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Bionanotecnología del Noa; ArgentinaFil: Agostini, Romina Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro de Estudios Fotosintéticos y Bioquímicos. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos; ArgentinaFil: Alvarez, Clarisa Ester. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro de Estudios Fotosintéticos y Bioquímicos. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos; ArgentinaFil: Klinke, Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Andreo, Carlos Santiago. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro de Estudios Fotosintéticos y Bioquímicos. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos; ArgentinaFil: Campos Bermudez, Valeria Alina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro de Estudios Fotosintéticos y Bioquímicos. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos; ArgentinaXLVIII Reunión Anual de la Sociedad Argentina de BiofísicaSan LuisArgentinaSociedad Argentina de BiofísicaUniversidad Nacional de San Lui

Volatile compounds released by maize grains and silks in response to infection by Fusarium verticillioides and its association with pathogen resistance

Many plants respond to fungal infections by producing and/or emitting a specific blend of oxylipins, some of them through the lipoxygenase (LOX) pathway. In vitro bioassays revealed that volatiles from silks and grains of a set of six maize genotypes with variable resistance to Fusarium verticillioides affected fungal growth in different ways. Analyses by solid phase microextraction and GC-MS showed different volatile profiles in silks and grains of each genotype. Susceptible genotypes with higher concentrations of precursor polyunsaturated fatty acids produced more volatiles, mainly C9 compounds, in comparison to moderately resistant ones. Real-time PCR from several lipoxygenase transcripts revealed that levels of gene expression depended on the genotype and the inoculation level and suggested that F. verticillioides could use compounds from the 9-LOX pathway to promote infection in grains. On the other hand, volatiles produced by the 13-LOX pathway were more important in moderately resistant genotypes and could be associated to field resistance. Results from this set of genotypes indicate that LOX-regulated volatile compounds might be important in F. verticillioides infection and should be targeted in further research to understand disease resistance.EEA PergaminoFil: Fauguel, Carolina Maria. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Pergamino; ArgentinaFil: Campos Bermudez, Valeria A. Centro de Estudios Fotosintéticos y Bioquíımicos; ArgentinaFil: Iglesias, Juliana. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Pergamino; ArgentinaFil: Fernandez, Mariana. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Pergamino; ArgentinaFil: Farroni, Abel Eduardo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Pergamino; ArgentinaFil: Andreo, C.S. Centro de Estudios Fotosintéticos y Bioquíımicos; ArgentinaFil: Presello, Daniel Alberto. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Pergamino; Argentin