RESUMO
Psittacanthus calyculatus parasitizes mesquite trees through a specialized structure called a haustorium, which, in the intrusive process, can cause cellular damage in the host tree and release DAMPs, such as ATP, sugars, RNA, and DNA. These are highly conserved molecules that primarily function as signals that trigger and activate the defense responses. In the present study, we generate extracellular DNA (exDNA) from mesquite (P. laevigata) tree leaves (self-exDNA) and P. calyculatus (non-self exDNA) mistletoe as DAMP sources to examine mesquite trees' capacity to identify specific self or non-self exDNA. We determined that mesquite trees perceive self- and non-self exDNA with the synthesis of O2â¢-, H2O2, flavonoids, ROS-enzymes system, MAPKs activation, spatial concentrations of JA, SA, ABA, and CKs, and auxins. Our data indicate that self and non-self exDNA application differs in oxidative burst, JA signaling, MAPK gene expression, and scavenger systems. This is the first study to examine the molecular biochemistry effects in a host tree using exDNA sources derived from a mistletoe.
Assuntos
Erva-de-Passarinho , Prosopis , Alarminas , DNA , Peróxido de Hidrogênio , ÁrvoresRESUMO
The Ja-Kids Longitudinal Study (JA-Kids) aims to improve the health and development of Jamaican children by identifying social, demographic, environmental and clinical factors that help or hinder these processes. As clinical indicators relied on maternal reporting, we aim to evaluate the quality of the self-reported data. Women were recruited across Jamaica during pregnancy or at delivery from July 1-30 September 2011. Indicators were compared between women recruited while pregnant and at delivery to understand possible differences between the sub-populations. Variables reported more than once between pregnancy and delivery were assessed to evaluate level of agreement (reliability). Clinical indicators from the literature were contrasted with study findings to determine how maternal reporting align with published prevalence (validity). Intra-class correlation and the kappa (κ) statistic were used to assess reliability while chi-squared, Fisher's-exact or students-t were used to compare differences over time; p values ≤0.05 were considered statistically significant. Women recruited during pregnancy (n = 3970) were younger, less parous and possibly more socially disadvantaged than those recruited at delivery (n = 5803). Socio-demographic and selected clinical indicators showed good to moderate (0.421 < κ < 0.681) reporting consistency between pregnancy and delivery for previous C-section (κ = 0.681), pre-existing diabetes mellitus (κ = 0.616) and prior twin gestations (0.580). Most conditions however showed only fair agreement (0.21 < κ < 0.40) including previous gestational hypertension (κ = 0.387), asthma (κ = 0.365), premature rupture of membranes (κ = 0.324), eclampsia (κ = 0.257) and essential hypertension (κ = 0.213). Infectious conditions had poor reliability. Prevalence rates for most conditions, except sickle cell disease, were lower than the published literature. Complications and outcomes which were well defined for women were better reported than those requiring clinical judgment (e.g. prior C-section versus specific hypertensive disorders of pregnancy). NCDs with only episodic acute effects were not well reported, e.g. asthma, hypertension and sickle cell disease. Maternal reporting of pregnancy complications needs to be interpreted with caution.
RESUMO
Neste artigo cotejamos concepções político-educacionais de Comênio e Skinner presentes, respectivamente, na Didática Magna e em Walden II. Problematizamos se o fato dos autores superestimarem o método de ensino - como se este fosse uma infalível garantia de êxito educacional - seria suficiente para irmaná- los. Seguindo a ideia de que é estruturalmente impossível controlar os efeitos da educação, constatamos que em Comênio, mas não em Skinner, ocorre um significativo arrefecimento de tal pretensa infalibilidade metodológica. Essa divergência entre os autores deriva do modo distinto com que cada um concebe a política e lida com as finalidades e impossibilidades da política e da educação.
En este artículo cotejamos concepciones político-educativas de Comenio y Skinner presentes en Didáctica Magna y Walden II. Problematizamos si el hecho de que los autores exageran en la valorización del método - como si fuera una infalible garantía de éxito en la educación - sería suficiente para hermanarlos. Siguiendo la idea de que es estructuralmente imposible controlar los efectos de la educación, constatamos que en Comenio, pero no en Skinner, ocurre un enfriamiento de tal pretendida infalibilidad metodologica. Esta divergencia deriva del modo distinto como cada autor concibe la política y se ocupa de las finalidades e imposibilidades de la política y de la educación.
In this paper, we compare the educational-political conceptions of Comenius and Skinner, presents in The Great Didactic and Walden II. We problematize if their overestimation of the teaching method - as if it were an infallible assurance of education success - is a sufficient criteria to take their theory as siblings. Following the idea that it is structurally impossible to control the effects of education, we verify that in Comenius, different from Skinner, occurs an expressive decline of such methodological infallibility. This difference derives from their radically distinct way to conceive politic and to deal with the aims and impossibilities of politics and education.
Assuntos
Humanos , Política , Psicanálise , Educação/métodosRESUMO
Plants produce species-specific herbivore-induced plant volatiles (HIPVs) after damage. We tested the hypothesis that herbivore-specific HIPVs prime neighboring plants to induce defenses specific to the priming herbivore. Since Manduca sexta (specialist) and Heliothis virescens (generalist) herbivory induced unique HIPV profiles in Nicotiana benthamiana, we used these HIPVs to prime receiver plants for defense responses to simulated herbivory (mechanical wounding and herbivore regurgitant application). Jasmonic acid (JA) accumulations and emitted volatile profiles were monitored as representative defense responses since JA is the major plant hormone involved in wound and defense signaling and HIPVs have been implicated as signals in tritrophic interactions. Herbivore species-specific HIPVs primed neighboring plants, which produced 2 to 4 times more volatiles and JA after simulated herbivory when compared to similarly treated constitutive volatile-exposed plants. However, HIPV-exposed plants accumulated similar amounts of volatiles and JA independent of the combination of priming or challenging herbivore. Furthermore, volatile profiles emitted by primed plants depended only on the challenging herbivore species but not on the species-specific HIPV profile of damaged emitter plants. This suggests that feeding by either herbivore species primed neighboring plants for increased HIPV emissions specific to the subsequently attacking herbivore and is probably controlled by JA.
Assuntos
Herbivoria/fisiologia , Nicotiana/imunologia , Nicotiana/metabolismo , Compostos Orgânicos Voláteis/metabolismo , Animais , Ciclopentanos/metabolismo , Manduca/fisiologia , Mariposas/fisiologia , Oxilipinas/metabolismo , Folhas de Planta/metabolismo , Nicotiana/parasitologiaRESUMO
The growth-defense trade-off in plant biology has gained enormous traction in the last two decades, highlighting the importance of understanding how plants deal with two of the greatest challenges for their survival and reproduction. It has been well established that in response to competition signals perceived by informational photoreceptors, shade-intolerant plants typically activate the shade-avoidance syndrome (SAS). In turn, in response to signals of biotic attack, plants activate a suite of defense responses, many of which are directed to minimize the loss of plant tissue to the attacking agent (broadly defined, the defense syndrome, DS). We argue that components of the SAS, including increased elongation, apical dominance, reduced leaf mass per area (LMA), and allocation to roots, are in direct conflict with configurational changes that plants require to maximize defense. We hypothesize that these configurational trade-offs provide a functional explanation for the suppression of components of the DS in response to competition cues. Based on this premise, we discuss recent advances in the understanding of the mechanisms by which informational photoreceptors, by interacting with jasmonic acid (JA) signaling, help the plant to make intelligent allocation and developmental decisions that optimize its configuration in complex biotic contexts.
Assuntos
Proteínas de Arabidopsis/metabolismo , Proteínas Cromossômicas não Histona/metabolismo , Ciclopentanos/metabolismo , Oxilipinas/metabolismo , Fotorreceptores de Plantas/metabolismo , Fitocromo/metabolismo , Viridiplantae , Desenvolvimento Vegetal/fisiologia , Doenças das Plantas/imunologia , Imunidade Vegetal/fisiologia , Folhas de Planta/metabolismo , Proteínas de Plantas/metabolismo , Raízes de Plantas/metabolismo , Transdução de Sinais , Viridiplantae/crescimento & desenvolvimento , Viridiplantae/imunologia , Viridiplantae/metabolismoRESUMO
Changes in abscisic acid (ABA), indole-3-acetic acid (IAA) and jasmonic acid (JA) content in developing calyx, fruits and leaves of Physalis peruviana L. plants were analysed. Plant hormones have been widely studied for their roles in the regulation of various aspects related to plant development and, in particular, into their action during development and ripening of fleshly fruits. The obtained evidences suggest that the functions of these hormones are no restricted to a particular development stage, and more than one hormone is involved in controlling various aspects of plant development. Our results will contribute to understand the role of these hormones during growth and development of calyx, fruits and leaves in cape gooseberry plants. This work offers a good, quickly and efficiently protocol to extract and quantify simultaneously ABA, IAA and JA in different tissues of cape gooseberry plants.
Assuntos
Ácido Abscísico/metabolismo , Ciclopentanos/metabolismo , Flores/crescimento & desenvolvimento , Frutas/metabolismo , Ácidos Indolacéticos/metabolismo , Oxilipinas/metabolismo , Physalis/metabolismo , Frutas/crescimento & desenvolvimento , Physalis/crescimento & desenvolvimento , Folhas de PlantaRESUMO
Natural and synthetic elicitors have contributed significantly to the study of plant immunity. Pathogen-derived proteins and carbohydrates that bind to immune receptors, allow the fine dissection of certain defence pathways. Lipids of a different nature that act as defence elicitors, have also been studied, but their specific effects have been less well characterized, and their receptors have not been identified. In animal cells, nanoliposomes of the synthetic cationic lipid 3-tetradecylamino-tert-butyl-N-tetradecylpropionamidine (diC14) activate the TLR4-dependent immune cascade. Here, we have investigated whether this lipid induces Arabidopsis defence responses. At the local level, diC14 activated early and late defence gene markers (FRK1, WRKY29, ICS1 and PR1), acting in a dose-dependent manner. This lipid induced the salicylic acid (SA)-dependent, but not jasmonic acid (JA)-dependent, pathway and protected plants against Pseudomonas syringae pv. tomato (Pst), but not Botrytis cinerea. diC14 was not toxic to plant or pathogen, and potentiated pathogen-induced callose deposition. At the systemic level, diC14 induced PR1 expression and conferred resistance against Pst. diC14-induced defence responses required the signalling protein EDS1, but not NDR1. Curiously, the lipid-induced defence gene expression was lower in the fls2/efr/cerk1 triple mutant, but still unchanged in the single mutants. The amidine headgroup and chain length were important for its activity. Given the robustness of the responses triggered by diC14, its specific action on a defence pathway and the requirement for well-known defence components, this synthetic lipid is emerging as a useful tool to investigate the initial events involved in plant innate immunity.
Assuntos
Amidinas/metabolismo , Arabidopsis/imunologia , Imunidade Vegetal , Arabidopsis/genética , Botrytis/imunologia , Cátions , Doenças das Plantas/imunologia , Doenças das Plantas/microbiologia , Pseudomonas syringae/imunologiaRESUMO
To investigate the role of jasmonates (JAs) in the ripening of Fragaria chiloensis fruit, two concentrations of methyl jasmonate (MeJA, 10 and 100 µM) were evaluated at 2, 5 and 9 d using an in vitro ripening system. Fruit quality parameters; the contents of anthocyanin, lignin and cell wall polymers; and the transcriptional profiles of several ripening-related genes were analyzed. MeJA accelerated fruit ripening by means of a transitory increase in the soluble solid content/titratable acidity ratio, anthocyanin accumulation and an increase in softening at day 5. The expression of several phenylpropanoid-related genes, primarily those associated with anthocyanin biosynthesis, was increased under MeJA treatment, which correlated with an increased accumulation of anthocyanin. MeJA also altered the expression profiles of some cell wall-modifying genes, namely, EG1 and XTH1, and these changes correlated with a transient reduction in the firmness of MeJA-treated fruits. MeJA-responsive elements were observed in the promoter region of the EG1 gene. MeJA also increased the expression of LOX, AOS and OPR3, genes involved in the biosynthesis of JAs, and these changes correlated with the transient activation of fruit ripening observed. Conversely, the expression of ethylene and lignin biosynthesis genes (ACS, ACO, CAD and POD27) increased in MeJA-treated fruits at day 9. The present findings suggest that JAs promote the ripening of non-climacteric fruits through their involvement in anthocyanin accumulation, cell wall modification and the biosynthesis of ethylene and JAs.
Assuntos
Acetatos/metabolismo , Ciclopentanos/metabolismo , Fragaria/genética , Frutas/metabolismo , Regulação da Expressão Gênica de Plantas , Expressão Gênica , Genes de Plantas , Oxilipinas/metabolismo , Desenvolvimento Vegetal/genética , Acetatos/farmacologia , Antocianinas/genética , Antocianinas/metabolismo , Parede Celular/efeitos dos fármacos , Parede Celular/metabolismo , Ciclopentanos/farmacologia , Etilenos/biossíntese , Fragaria/efeitos dos fármacos , Fragaria/crescimento & desenvolvimento , Fragaria/metabolismo , Frutas/efeitos dos fármacos , Frutas/crescimento & desenvolvimento , Expressão Gênica/efeitos dos fármacos , Lignina/biossíntese , Lignina/genética , Oxilipinas/farmacologia , Desenvolvimento Vegetal/efeitos dos fármacos , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismoRESUMO
The quest for sustainability in agricultural production through conservation management practices such as no-tillage, has favored the biochemical processes of soil, such as soil arbuscular mycorrhizal fungi (AMFs), which promote a significant increase in specific surface absorption of the root system of plants. The objective of this study was to evaluate the root colonization, spore density and diversity of AMFs in rhizosphere of corn and soybean grown under no-tillage with different cover crops and compared an area conventional tillage and fallow, in Uberaba, state of Minas Gerais. The corn and soybeans were rotated with millet, crotalaria and brachiaria. The experimental design was randomized blocks, with split plots. The experiment was established in 2000, and in 2007 assessed the colonization (COL) and spore density (ESP) (0.0-0.05m and 0.05-0.10m). In the layer of 0.0-0.10m evaluated the diversity of AMFs. It was found that there was a strong effect of culture on COL and ESP. However, the effect of the covers and management was seen only in 0.0-0.05m. The roots of corn has a higher percentages of COL and ESP compared with soybeans, for the coverage Brachiaria and millet. The mycorrhizal colonization of soybean and maize in Cerrado area was up 80% for soybeans and up 95% for corn. Conventional tillage soil the lowest number of AMFs species in relation to the coverage of mil
A busca da sustentabilidade na produção agrícola através de manejos conservacionistas, como o sistema plantio direto, tem favorecido os processos bioquímicos do solo como dos fungos micorrízicos arbusculares (FMAs), os quais promovem um aumento expressivo da superfície específica de absorção do sistema radicular das plantas. Sendo assim, o objetivo deste trabalho foi avaliar a colonização micorrízica, densidade de esporos e a diversidade de FMAs na rizosfera de milho e soja cultivados sob plantio direto com diferentes plantas de cobertura e comparadas a uma área de preparo convencional e pousio, em Uberaba, MG. As culturas de milho e soja foram rotacionadas com milheto, crotalária e braquiária. O delineamento experimental foi em blocos casualizados, com parcelas subdivididas. O experimento foi implantado em 2000 e, em 2007 avaliou-se a colonização radicular por FMAs (COL) e densidade de esporos no solo (ESP) nas profundidades de 0,0-0,05 m e 0,05-0,10 m, já a avaliação da diversidade de FMAs foi na profundidade de 0,0-0,10 m. Verificou-se que houve efeito significativo das culturas sobre COL e ESP. Entretanto, o efeito das coberturas e do manejo foi verificado apenas em 0,0-0,05 m. As raízes de milho apresentam maiores porcentagens de COL e ESP quando comparado com a soja, para as coberturas de braquiária e milheto. A colonização micorrízica da soja e do milho na área de Cerrad
RESUMO
The quest for sustainability in agricultural production through conservation management practices such as no-tillage, has favored the biochemical processes of soil, such as soil arbuscular mycorrhizal fungi (AMFs), which promote a significant increase in specific surface absorption of the root system of plants. The objective of this study was to evaluate the root colonization, spore density and diversity of AMFs in rhizosphere of corn and soybean grown under no-tillage with different cover crops and compared an area conventional tillage and fallow, in Uberaba, state of Minas Gerais. The corn and soybeans were rotated with millet, crotalaria and brachiaria. The experimental design was randomized blocks, with split plots. The experiment was established in 2000, and in 2007 assessed the colonization (COL) and spore density (ESP) (0.0-0.05m and 0.05-0.10m). In the layer of 0.0-0.10m evaluated the diversity of AMFs. It was found that there was a strong effect of culture on COL and ESP. However, the effect of the covers and management was seen only in 0.0-0.05m. The roots of corn has a higher percentages of COL and ESP compared with soybeans, for the coverage Brachiaria and millet. The mycorrhizal colonization of soybean and maize in Cerrado area was up 80% for soybeans and up 95% for corn. Conventional tillage soil the lowest number of AMFs species in relation to the coverage of mil
A busca da sustentabilidade na produção agrícola através de manejos conservacionistas, como o sistema plantio direto, tem favorecido os processos bioquímicos do solo como dos fungos micorrízicos arbusculares (FMAs), os quais promovem um aumento expressivo da superfície específica de absorção do sistema radicular das plantas. Sendo assim, o objetivo deste trabalho foi avaliar a colonização micorrízica, densidade de esporos e a diversidade de FMAs na rizosfera de milho e soja cultivados sob plantio direto com diferentes plantas de cobertura e comparadas a uma área de preparo convencional e pousio, em Uberaba, MG. As culturas de milho e soja foram rotacionadas com milheto, crotalária e braquiária. O delineamento experimental foi em blocos casualizados, com parcelas subdivididas. O experimento foi implantado em 2000 e, em 2007 avaliou-se a colonização radicular por FMAs (COL) e densidade de esporos no solo (ESP) nas profundidades de 0,0-0,05 m e 0,05-0,10 m, já a avaliação da diversidade de FMAs foi na profundidade de 0,0-0,10 m. Verificou-se que houve efeito significativo das culturas sobre COL e ESP. Entretanto, o efeito das coberturas e do manejo foi verificado apenas em 0,0-0,05 m. As raízes de milho apresentam maiores porcentagens de COL e ESP quando comparado com a soja, para as coberturas de braquiária e milheto. A colonização micorrízica da soja e do milho na área de Cerrad