RESUMEN
In the course of plant evolution from aquatic to terrestrial environments, land plants (embryophytes) acquired a diverse array of specialized metabolites, including phenylpropanoids, flavonoids and cuticle components, enabling adaptation to various environmental stresses. While embryophytes and their closest algal relatives share candidate enzymes responsible for producing some of these compounds, the complete genetic network for their biosynthesis emerged in embryophytes. In this review, we analysed genomic data from chlorophytes, charophytes and embryophytes to identify genes related to phenylpropanoid, flavonoid and cuticle biosynthesis. By integrating published research, transcriptomic data and metabolite studies, we provide a comprehensive overview on how these specialized metabolic pathways have contributed to plant defence responses to pathogens in non-vascular bryophytes and vascular plants throughout evolution. The evidence suggests that these biosynthetic pathways have provided land plants with a repertoire of conserved and lineage-specific compounds, which have shaped immunity against invading pathogens. The discovery of additional enzymes and metabolites involved in bryophyte responses to pathogen infection will provide evolutionary insights into these versatile pathways and their impact on environmental terrestrial challenges.This article is part of the theme issue 'The evolution of plant metabolism'.
Asunto(s)
Interacciones Huésped-Patógeno , Evolución Biológica , Embryophyta/metabolismo , Embryophyta/genética , Embryophyta/inmunología , Plantas/microbiología , Plantas/inmunología , Plantas/metabolismo , Enfermedades de las Plantas/microbiología , Enfermedades de las Plantas/inmunologíaRESUMEN
INTRODUCTION: Several Picornaviruses are pathogens that generate serious problems for human and animal health worldwide. Vaccination is an attractive approach to fight against picornaviruses. In this regard, the development of low-cost vaccines is a priority to ensure coverage; especially in developing and low-income countries. In this context, plant-made vaccines are a convenient technology since plant cells are low-cost bioreactors capable of producing complex antigens that preserve their antigenic determinants; moreover, they can serve as biocapsules to achieve oral delivery. AREAS COVERED: In the present review the advances in the development of plant-made vaccines against picornaviruses are summarized and placed in perspective. The main diseases that have been targeted using this approach include Poliovirus, Food and mouth disease virus, Hepatitis A virus, and Enterovirus 71. EXPERT OPINION: Several vaccine candidates against picornavirus have been characterized at the preclinical level; with many of them capable of inducing humoral and cellular responses that led to neutralization of pathogens when evaluated in vitro and test animal challenge assays. Plant-made vaccines are a promise to fight picornaviruses; especially in the developing world where limited resources hamper vaccination coverage. A critical analysis of the road ahead for this technology is provided.
Asunto(s)
Antígenos de Plantas/inmunología , Infecciones por Picornaviridae/prevención & control , Vacunas Virales/administración & dosificación , Animales , Países en Desarrollo , Humanos , Infecciones por Picornaviridae/inmunología , Plantas/inmunología , Vacunación , Vacunas Virales/economía , Vacunas Virales/inmunologíaRESUMEN
BACKGROUND: Pathogens use multiple mechanisms to disrupt cell functioning in their host and allow pathogenesis. These mechanisms involve communication between the pathogen and the host cell through protein-protein interactions. METHODS: Protein-protein interactions chains referred to as signal transduction pathways are the processes by which a chemical or physical signal transmits through a cell as series of molecular events so the pathogen needs to intercept these molecular pathways at few positions to induce pathogenesis such as pathogen viability, infection or hypersensitivity. RESULTS: The pathogen nodes of interception are not necessarily the most immunogenic; so that novel immunogenicity-improvement strategies need to be developed thought a chemical conjugation of the pathogen-carrier nodes to develop an efficient immune response in order to block pathogenesis. On the other hand, if pathogen-carriers are immunogens; toleration ought to be induced by this conjugation avoiding hypersensitivity. Thus, this paper addresses the biological plausibility of plant-phenolics as pathogen-carrier immunogenicity modulator haptens. CONCLUSION: The plant-phenolic compounds have in their structure functional groups such as hydroxyl, carbonyl, carboxyl, ester, or ether, capable of reacting with the amino or carbonyl groups of the amino acids of a pathogen-carrier to form conjugates. Besides, the varied carbon structures these phenolic compounds have; it is possible to alter the pathogen-carrier related factors that determine the immunogenicity: 1) Structural complexity, 2) Molecular size, 3) Structural heterogeneity, 4) Accessibility to antigenic determinants or epitopes, 5) Optical configuration, 6) Physical state, or 7) Molecular rigidity.
Asunto(s)
Inmunidad Adaptativa/efectos de los fármacos , Haptenos/inmunología , Interacciones Huésped-Patógeno/inmunología , Inmunidad Innata/efectos de los fármacos , Fenoles/inmunología , Plantas/inmunología , Inmunidad Adaptativa/inmunología , Aminoácidos/química , Aminoácidos/inmunología , Animales , Células Presentadoras de Antígenos/efectos de los fármacos , Células Presentadoras de Antígenos/inmunología , Humanos , Inmunidad Innata/inmunología , Fenoles/química , Plantas/química , Transducción de SeñalRESUMEN
Mammals sense self or non-self extracellular or extranuclear DNA fragments (hereinafter collectively termed eDNA) as indicators of injury or infection and respond with immunity. We hypothesised that eDNA acts as a damage-associated molecular pattern (DAMP) also in plants and that it contributes to self versus non-self discrimination. Treating plants and suspension-cultured cells of common bean (Phaseolus vulgaris) with fragmented self eDNA (obtained from other plants of the same species) induced early, immunity-related signalling responses such as H2O2 generation and MAPK activation, decreased the infection by a bacterial pathogen (Pseudomonas syringae) and increased an indirect defence to herbivores (extrafloral nectar secretion). By contrast, non-self DNA (obtained from lima bean, Phaseolus lunatus, and Acacia farnesiana) had significantly lower or no detectable effects. Only fragments below a size of 700â¯bp were active, and treating the eDNA preparation DNAse abolished its inducing effects, whereas treatment with RNAse or proteinase had no detectable effect. These findings indicate that DNA fragments, rather than small RNAs, single nucleotides or proteins, accounted for the observed effects. We suggest that eDNA functions a DAMP in plants and that plants discriminate self from non-self at a species-specific level. The immune systems of plants and mammals share multiple central elements, but further work will be required to understand the mechanisms and the selective benefits of an immunity response that is triggered by eDNA in a species-specific manner.
Asunto(s)
Alarminas/genética , Ácidos Nucleicos Libres de Células/fisiología , Plantas/inmunología , Alarminas/metabolismo , Alarminas/fisiología , Ácidos Nucleicos Libres de Células/genética , Ácidos Nucleicos Libres de Células/inmunología , ADN/inmunología , ADN/metabolismo , Inmunidad Innata/genética , Sistema de Señalización de MAP Quinasas/inmunología , Phaseolus/genética , Phaseolus/inmunología , Plantas/genética , Especies Reactivas de Oxígeno/metabolismo , Autotolerancia/inmunologíaRESUMEN
The field of tRNA biology, encompassing the functional and structural complexity of tRNAs, has fascinated scientists over the years and is continuously growing. Besides their fundamental role in protein translation, new evidence indicates that tRNA-derived molecules also regulate gene expression and protein synthesis in all domains of life. This review highlights some of the recent findings linking tRNA transcription and modification with plant cell growth and response to pathogens. In fact, mutations in proteins directly involved in tRNA synthesis and modification most often lead to pleiotropic effects on plant growth and immunity. As plants need to optimize and balance their energy and nutrient resources towards growth and defense, regulatory pathways that play a central role in integrating tRNA transcription and protein translation with cell growth control and organ development, such as the auxin-TOR signaling pathway, also influence the plant immune response against pathogens. As a consequence, distinct pathogens employ an array of effector molecules including tRNA fragments to target such regulatory pathways to exploit the plant's translational capacity, gain access to nutrients and evade defenses. An example includes the RNA polymerase III repressor MAF1, a conserved component of the TOR signaling pathway that controls ribosome biogenesis and tRNA synthesis required for plant growth and which is targeted by a pathogen effector molecule to promote disease. This article is part of a Special Issue entitled: SI: Regulation of tRNA synthesis and modification in physiological conditions and disease edited by Dr. Boguta Magdalena.
Asunto(s)
Regulación de la Expresión Génica de las Plantas , Plantas/genética , ARN de Planta/biosíntesis , ARN de Transferencia/biosíntesis , Transcripción Genética , Secuencia de Aminoácidos , Interacciones Huésped-Patógeno , Ácidos Indolacéticos , Modelos Moleculares , Mutación , Desarrollo de la Planta/genética , Enfermedades de las Plantas/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas/inmunología , Conformación Proteica , ARN Polimerasa III/genética , ARN Polimerasa III/metabolismo , ARN de Planta/genética , ARN de Transferencia/genética , Alineación de Secuencia , Homología de Secuencia de Aminoácido , Serina-Treonina Quinasas TOR/fisiologíaRESUMEN
Under environmental conditions, plants are constantly exposed to a wide range of biotic interactions, which include insects, and pathogens. Usually scientists are tempted to study each association individually, which reduces the complexity of the interaction. This restricted view of the problem does not consider that plants are the ballroom in which a multitude of organisms are constantly interacting with each other affecting not only plant responses but also how one organism responds to the other. Plants attacked by insects and pathogens display profound physiological, morphological and chemical changes or adaptations that result in organism attraction or avoidance, depending on the species involved. Therefore, many researchers worldwide have decided to study this phenomenon in a more holistic view, integrating genetics, ecology and physiology to depict these complex interactions. In this review, we will discuss how plant infection by pathogens may affect insect behavior and vice-versa and how plants cope with these multitude of biotic stresses.
Asunto(s)
Interacciones Huésped-Parásitos , Interacciones Huésped-Patógeno , Insectos/fisiología , Plantas/microbiología , Plantas/parasitología , Adaptación Fisiológica , Animales , Enfermedades de las Plantas/inmunología , Enfermedades de las Plantas/microbiología , Enfermedades de las Plantas/parasitología , Plantas/inmunologíaRESUMEN
NOD Like Receptors (NLRs) are the most abundant cytoplasmic immune receptors in plants and animals and they similarly act sensing pathogen invasion and activating immune response. Despite the fact that plant and mammals NLRs share homology.; with some protein structure differences.; for signalling pathway.; divergent evolution of the receptors has been hypothesized. Next generation genome sequencing has contributed to the description of NLRs in phyla others than plants and mammals and leads to new knowledge about NLRs evolution along phylogeny. Full comprehension of NLR-mediated immune response in plant could contribute to the understanding of animal NLRs physiology and/or pathology.
Asunto(s)
Evolución Molecular , Invertebrados/genética , Mamíferos/genética , Proteínas NLR/genética , Inmunidad de la Planta/genética , Plantas/genética , Animales , Dosificación de Gen , Regulación de la Expresión Génica , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Invertebrados/inmunología , Invertebrados/microbiología , Invertebrados/virología , Mamíferos/inmunología , Mamíferos/microbiología , Mamíferos/virología , Proteínas NLR/clasificación , Proteínas NLR/inmunología , Filogenia , Plantas/inmunología , Plantas/microbiología , Plantas/virología , Transducción de SeñalRESUMEN
The discovery of novel plant resistance (R) genes (including their homologs and analogs) opened interesting possibilities for controlling plant diseases caused by several pathogens. However, due to environmental pressure and high selection operated by pathogens, several crop plants have lost specificity, broad-spectrum or durability of resistance. On the other hand, the advances in plant genome sequencing and biotechnological approaches, combined with the increasing knowledge on Rgenes have provided new insights on their applications for plant genetic breeding, allowing the identification and implementation of novel and efficient strategies that enhance or optimize their use for efficiently controlling plant diseases. The present review focuses on main perspectives of application of R-genes and its co-players for the acquisition of resistance to pathogens in cultivated plants, with emphasis on biotechnological inferences, including transgenesis, cisgenesis, directed mutagenesis and gene editing, with examples of success and challenges to be faced.
Asunto(s)
Proteínas de Arabidopsis/inmunología , Resistencia a la Enfermedad/genética , Regulación de la Expresión Génica de las Plantas/inmunología , Enfermedades de las Plantas/inmunología , Proteínas de Plantas/inmunología , Plantas/genética , Proteínas Serina-Treonina Quinasas/inmunología , Proteínas de Arabidopsis/genética , Biotecnología/métodos , Sistemas CRISPR-Cas , Edición Génica/métodos , Interacciones Huésped-Patógeno/genética , Interacciones Huésped-Patógeno/inmunología , Mutagénesis Sitio-Dirigida , Fitomejoramiento/métodos , Enfermedades de las Plantas/genética , Inmunidad de la Planta/genética , Proteínas de Plantas/genética , Plantas/inmunología , Plantas/microbiología , Plantas/virología , Plantas Modificadas Genéticamente , Isoformas de Proteínas/genética , Isoformas de Proteínas/inmunología , Proteínas Serina-Treonina Quinasas/genética , Transducción de SeñalRESUMEN
Phytopathogenic microorganisms have a significant influence on survival and productivity of several crop plants. Transcription factors (TFs) are important players in the response to biotic stresses, as insect attack and pathogen infection. In face of such adversities many TFs families have been previously reported as differentially expressed in plants as a reaction to bacterial, fungal and viral infection. This review highlights recent progresses in understanding the structure, function, signal regulation and interaction of transcription factors with other proteins in response to pathogens. Hence, we focus on three families of transcription factors: ERF, bZIP and WRKY, due to their abundance, importance and the availability of functionally well-characterized members in response to pathogen attack. Their roles and the possibilities related to the use of this knowledge for engineering pathogen resistance in crop plants are also discussed.
Asunto(s)
Proteínas de Arabidopsis/inmunología , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico/inmunología , Proteínas de Unión al ADN/inmunología , Resistencia a la Enfermedad/genética , Enfermedades de las Plantas/inmunología , Proteínas de Plantas/inmunología , Plantas/genética , Factores de Transcripción/inmunología , Proteínas de Arabidopsis/genética , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico/genética , Proteínas de Unión al ADN/genética , Regulación de la Expresión Génica de las Plantas/inmunología , Interacciones Huésped-Patógeno/genética , Interacciones Huésped-Patógeno/inmunología , Enfermedades de las Plantas/genética , Inmunidad de la Planta/genética , Proteínas de Plantas/genética , Plantas/inmunología , Plantas/microbiología , Plantas/virología , Plantas Modificadas Genéticamente , Mapeo de Interacción de Proteínas , Isoformas de Proteínas/genética , Isoformas de Proteínas/inmunología , Transducción de Señal , Estrés Fisiológico/genética , Estrés Fisiológico/inmunología , Factores de Transcripción/genética , Transcripción GenéticaRESUMEN
Some DNA viruses overcome plant defenses by producing a suppressor protein that blocks the silencing of viral genes.
Asunto(s)
Geminiviridae/fisiología , Silenciador del Gen , Evasión Inmune , Proteínas de Plantas/antagonistas & inhibidores , Plantas/inmunología , Plantas/virología , Proteínas Virales/metabolismo , Interacciones Huésped-Patógeno , Modelos BiológicosRESUMEN
Plants constitute excellent sources for pathogen nutrition and survival. To fight against pathogen attack, higher plants have developed a sophisticated immune system responsible for pathogen recognition and activation of downstream defense responses. After pathogen perception, mitochondria play an important role in the defense strategy of the plant cell, integrating and amplifying diverse signals such as salicylic acid, nitric oxide, reactive oxygen species (ROS) or pathogen elicitors. Signals perceived by mitochondria usually impact on their normal function, destabilizing the organelle, generating changes in respiration, membrane potential and ROS production. At this stage, mitochondria produce several signals influencing the redox state of the cell and promoting changes in the expression of nuclear genes by mitochondrial retrograde regulation. At more advanced stages, they promote programmed cell death in order to avoid pathogen propagation to the whole plant. Recent evidence indicates that plants and pathogens have evolved mechanisms to modulate the immune response by acting on mitochondrial functions. In this review, we summarize knowledge about the involvement of mitochondria in different aspects of the response of plants to pathogen attack.
Asunto(s)
Mitocondrias/metabolismo , Plantas/inmunología , Plantas/microbiología , Apoptosis , Regulación de la Expresión Génica de las Plantas , Mitocondrias/efectos de los fármacos , Óxido Nítrico/metabolismo , Oxidación-Reducción , Plantas/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Ácido Salicílico/metabolismoRESUMEN
Vaccines against hypertension constitute a viable approach to decrease blood pressure. In particular, two vaccines against hypertension (HP) targeting angiotensin II (AgII) have showed promising results and these are currently on evaluation in clinical trials. In parallel, plant-based vaccines have become a biotechnological application that has been assessed in clinical trials for some cases. This report proposes a hypothesis that involves developing a plant-based vaccine against HP. It is hypothesized that a plant-based vaccine having AgII or its AT1 receptor (ATR1) as targets, constitutes a safe, suitable and efficient therapeutic approach for HP. It is known that a number of carrier proteins can be produced in plants retaining its adjuvanticity. Therefore the production in plants of chimeric proteins where either AgII or ATR1 domains are fused to these carriers would be a promising approach to be investigated. Mucosal immunization using plant-derived AgII/ATR1 chimeric proteins would imply several advantages such as low cost and friendly delivery. However due to the lack of a detailed knowledge on the physiological role of AgII at the gastrointestinal tract, the effects of partially blocking the AgII action must be extensively evaluated. An alternative related to this aspect would be the use of transient expression systems where productivity is sufficiently high to allow the purification of the antigen of interest at convenient yields, so that it can constitute a parenteral vaccine. Proving the concept for a plant-based vaccine against HP may have profound implications on the development of a new HP therapy which offers convenient features such as low cost and easier compliance in comparison to pharmacological treatment.
Asunto(s)
Hipertensión/terapia , Plantas/inmunología , Vacunas/uso terapéutico , HumanosRESUMEN
Herbivores may interact with each other through resource competition, but also through their impact on plant defence. We recently found that the spider mite Tetranychus evansi down-regulates plant defences in tomato plants, resulting in higher rates of oviposition and population growth on previously attacked than on unattacked leaves. The danger of such down-regulation is that attacked plants could become a more profitable resource for heterospecific competitors, such as the two-spotted spider mite Tetranychus urticae. Indeed, T. urticae had an almost 2-fold higher rate of oviposition on leaf discs on which T. evansi had fed previously. In contrast, induction of direct plant defences by T. urticae resulted in decreased oviposition by T. evansi. Hence, both herbivores affect each other through induced plant responses. However, when populations of T. evansi and T. urticae competed on the same plants, populations of the latter invariably went extinct, whereas T. evansi was not significantly affected by the presence of its competitor. This suggests that T. evansi can somehow prevent its competitor from benefiting from the down-regulated plant defence, perhaps by covering it with a profuse web. Indeed, we found that T. urticae had difficulties reaching the leaf surface to feed when the leaf was covered with web produced by T. evansi. Furthermore, T. evansi produced more web when exposed to damage or other cues associated with T. urticae. We suggest that the silken web produced by T. evansi serves to prevent competitors from profiting from down-regulated plant defences.
Asunto(s)
Herbivoria/fisiología , Ácaros/fisiología , Plantas/inmunología , Animales , Regulación hacia Abajo/inmunología , Solanum lycopersicum/inmunología , Hojas de la Planta , Crecimiento Demográfico , Tetranychidae/fisiologíaRESUMEN
Plants have sophisticated defense systems to protect their tissues against the attack of herbivorous organisms. Many of these defenses are orchestrated by the oxylipin jasmonate. A growing body of evidence indicates that the expression of jasmonate-induced responses is tightly regulated by the ecological context of the plant. Ecological information is provided by molecular signals that indicate the nature of the attacker, the value of the attacked organs, phytochrome status and thereby proximity of competing plants, association with beneficial organisms and history of plant interactions with pathogens and herbivores. This review discusses recent advances in this field and highlights the need to map the activities of informational modulators to specific control points within our emerging model of jasmonate signaling.
Asunto(s)
Ciclopentanos/inmunología , Oxilipinas/inmunología , Reguladores del Crecimiento de las Plantas/inmunología , Inmunidad de la Planta/inmunología , Plantas/inmunología , Transducción de Señal/inmunología , Ciclopentanos/metabolismo , Ecosistema , Regulación de la Expresión Génica de las Plantas , Modelos Biológicos , Oxilipinas/metabolismo , Reguladores del Crecimiento de las Plantas/metabolismo , Plantas/genética , Plantas/metabolismo , Estrés FisiológicoRESUMEN
In eukaryotic genomes, gene expression and DNA recombination are affected by structural chromatin traits. Chromatin structure is shaped by the activity of enzymes that either introduce covalent modifications in DNA and histone proteins or use energy from ATP to disrupt histone-DNA interactions. The genomic 'marks' that are generated by covalent modifications of histones and DNA, or by the deposition of histone variants, are susceptible to being altered in response to stress. Recent evidence has suggested that proteins generating these epigenetic marks play crucial roles in the defence against pathogens. Histone deacetylases are involved in the activation of jasmonic acid- and ethylene-sensitive defence mechanisms. ATP-dependent chromatin remodellers mediate the constitutive repression of the salicylic acid-dependent pathway, whereas histone methylation at the WRKY70 gene promoter affects the activation of this pathway. Interestingly, bacterial-infected tissues show a net reduction in DNA methylation, which may affect the disease resistance genes responsible for the surveillance against pathogens. As some epigenetic marks can be erased or maintained and transmitted to offspring, epigenetic mechanisms may provide plasticity for the dynamic control of emerging pathogens without the generation of genomic lesions.
Asunto(s)
Epigénesis Genética/genética , Plantas/genética , Plantas/inmunología , Metilación de ADN/fisiología , Histonas/metabolismoRESUMEN
The serine and cysteine peptidase inhibitor, BbCI, isolated from Bauhinia bauhinioides seeds, is similar to the classical plant Kunitz inhibitor, STI, but lacks disulphide bridges and methionine residues. BbCI blocks activity of the serine peptidases, elastase (Kiapp 5.3 nM) and cathepsin G (Kiapp 160.0 nM), and the cysteine peptidase cathepsin L (Kiapp 0.2 nM). These three peptidases play important roles in the inflammatory process. We measured the effects of BbCI on paw oedema and on leucocyte accumulation in pleurisy, both induced by carrageenan. Leucocyteendothelial cell interactions in scrotal microvasculature in Wistar rats were investigated using intravital microscopy. Cytokine levels in pleural exudate and serum were measured by elisa.Pretreatment of the animals with BbCI (2.5 mg·kg−1), 30 min before carrageenan-induced inflammation, effectively reduced paw oedema and bradykinin release, neutrophil migration into the pleural cavity. The number of rolling, adhered and migrated leucocytes at the spermatic fascia microcirculation following carrageenan injection into the scrotum were reduced by BbCI pretreatment. Furthermore, levels of the rat chemokine cytokine-induced neutrophil chemo-attractant-1 were significantly reduced in both pleural exudates and serum from animals pretreated with BbCI. Levels of interleukin-1â or tumour necrosis factor-á, however, did not change.Taken together, our data suggest that the anti-inflammatory properties of BbCI may be useful in investigations of other pathological processes in which human neutrophil elastase, cathepsin G and cathepsin L play important roles.
Asunto(s)
Animales , Ratas , Bauhinia/microbiología , Bradiquinina , Citocinas , Plantas/inmunología , Preparaciones de Plantas/antagonistas & inhibidores , Elastasa Pancreática , PleuresiaRESUMEN
The predators Hippodamia convergens Guérin-Menéville (Coleoptera: Coccinelidae) and Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae), are frequently observed on vegetable crops, especially on tomato plants, as well as on flowers of several plants around crop fields. It is well known that when predators feed on pollen and nectar they can increase their longevity and reproductive capacity. The objective of this work was to identify plants that could be a pollen source for H. convergens and C. externa in order to develop strategies to attract and keep these predators in vegetable fields like the tomato crop. Adults of C. externa (53 individuals) and H. convergens (43 individuals) were collected in fields from 2004-2005 at Embrapa Hortaliças, Brasília, Federal District. The insects were processed by the acetolysis method and pollen from them was extracted and identified. A total of 11335 grains of pollen belonging to 21 families were extracted from C. externa. A total of 46 pollen grains belonging to ten families were extracted from H. convergens. The Poaceae family was the most abundant one for C. externa while Asteraceae was the commonest pollen for H. convergens. The importance of pollen from different plant species as a food resource for each predator species gives an indication of the importance of plant community structure inside and around crop fields for the establishment of these predator populations and to enhance conservation biological control.(AU)
Os predadores Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae) e Hippodamia convergens Guérin-Menéville (Coleoptera: Coccinelidae) são frequentemente observados em cultivos de hortaliças, especialmente tomateiros, bem como sobre flores de diversas plantas próximas aos cultivos. Sabe-se que os predadores, quando se alimentam de pólen e néctar, aumentam a sua longevidade e a sua capacidade reprodutiva. O objetivo deste trabalho foi identificar as plantas que poderiam servir de fonte de pólen para as espécies selecionadas, com vistas a desenvolver estratégias para atrair e manter estas espécies em cultivos de hortaliças, especialmente de tomateiro. Adultos de C. externa (53 indivíduos) e H. convergens (43 indivíduos) foram coletados em 2005 no campo experimental da Embrapa Hortaliças, Brasília, Distrito Federal. Os insetos foram processados pelo método de acetólise e os grãos de pólen, extraídos e identificados. Um total de 11335 grãos de pólen, pertencentes a 21 famílias foi identificado para C. externa, enquanto que 46 grãos de pólen, pertencentes a dez famílias botânicas, foram identificados para H. convergens. O pólen da família Poaceae foi o mais abundante para C. externa, e o pólen da família Asteraceae foi o mais comum para H. convergens. A importância relativa do pólen de diferentes espécies de plantas como recursos alimentares para cada espécie predadora dá indicações da importância da flora dentro e no entorno da cultura para o estabelecimento das populações desses predadores e incremento do controle biológico conservativo.(AU)
Asunto(s)
Plantas/inmunología , Cadena Alimentaria , Polen/efectos adversosRESUMEN
The plant hormones jasmonic acid and methyl jasmonate, along with their intermediate compounds, produced in the octadecanoid pathway, are important signaling molecules that are collectively called jasmonates. These are widespread in the plant kingdom and play crucial roles in biotic/abiotic stress responses, as well as in processes related to plant growth and development. Recently, it has been shown that jasmonates are also involved in reproductive processes. We present the most recent findings related to the biosynthesis, regulation and signaling mechanisms of jasmonates. Additionally, we discuss the identification of [(+)-7-iso-JA-L-Ile] as the active biological hormonal form of jasmonate; this fills the greatest gap in our knowledge about the signaling mechanism that is responsible for the activation of downstream genes in the jasmonate-signaling cascade. The identification of several Arabidopsis thaliana mutants was crucial to the elucidation of the signaling mechanisms involved in jasmonate-mediated responses. Finally, the involvement of jasmonates in the reproductive process of Nicotiana tabacum L. is briefly discussed, since some of the main enzymes of the jasmonic acid biosynthesis pathway were identified in a stigma/style expressed sequence tag database (TOBEST) of this Solanaceae species.
Asunto(s)
Ciclopentanos/metabolismo , Oxilipinas/metabolismo , Reguladores del Crecimiento de las Plantas/metabolismo , Plantas/inmunología , Plantas/metabolismo , Secuencia de Aminoácidos , Ciclopentanos/química , Datos de Secuencia Molecular , Oxilipinas/química , Reguladores del Crecimiento de las Plantas/química , Proteínas de Plantas/química , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas/genética , Plantas Modificadas Genéticamente , Reproducción , Transducción de SeñalRESUMEN
Defensin, thionin and lipid transfer protein (LTP) gene families, which antimicrobial activity has an attractive use in protein engineering and transgenic production of agronomical important plants, have been here functionally reviewed. Also, a transcriptional overview of a set of plant SuperSAGE libraries and analysis looking for 26 bp tags possibly annotated for those families is presented. Tags differentially expressed (p = 0.05) or constitutively transcribed were identified from leaves or roots SuperSAGE libraries from important Brazilian plant species [cowpea (Vigna unguiculata (L.) Walp.), soybean (Glycine max (L.) Merr.) and modern sugarcane hybrids (Saccharum spp.)] submitted to abiotic [salt (100 mM NaCl) or drought] or biotic stresses [fungus inoculation (Phakopsora pachyrhizi; Asiatic Soyben Rust phytopathogen)]. The diverse transcriptional patterns observed, probably related to the variable range of targets and functions involved, could be the first step to unravel the antimicrobial peptide world and the plant stress response relationship. Moreover, SuperSAGE opens the opportunity to find some SNPs or even rare transcript that could be important on plant stress resistance mechanisms. Putative defensin or LTP identified by SuperSAGE following a specific plant treatment or physiological condition could be useful for future use in genetic improvement of plants.