RESUMO
Many natural compounds can activate the plant immunity, and for this reason, they have attracted special interest in crop disease management. Previously, we isolated from strawberry leaves an ellagitannin (HeT), which elicits plant defense responses. In this research, we investigated bioactive compounds from field-collected strawberry leaves capable of inducing defense responses in Arabidopsis thaliana against a bacterial pathogen. Methanolic extracts of strawberry leaves sampled at different months were obtained and compared. The highest content of total soluble phenolic compounds was found in the methanolic extracts of leaves sampled in December (DME). The defense response induced in A. thaliana by DME was attributed to two ellagitannins, the HeT and galloyl-HHDP-glucose. Both compounds exhibited phytoprotective effects against Pseudomonas viridiflava and induced the expression of PDF1.2 and PR1 genes. These results provide an economic value to strawberry leaves, normally discarded at the end of the harvest stage of the crop, as a raw material for plant health enhancer bioinputs.
Assuntos
Fragaria , Fragaria/genética , Taninos Hidrolisáveis , Folhas de Planta , Pseudomonas , Estações do AnoRESUMO
HeT (1-0-galloyl-2,3; 4,6-bis-hexahydroxydiphenoyl-ß-D-glucopyranose) is a penta-esterified ellagitannin obtained from strawberry leaves. Previous studies have shown that foliar application of HeT prior to inoculation with a virulent pathogen increases the resistance toward Colletotrichum acutatum in strawberry plants and to Xanthomonas citri subsp. citri in lemon plants. In this work we report that HeT induces an immediate leak of electrolytes, the hyperpolarization of the cellular membrane, a rapid Ca2+ influx to the cytoplasm during the first few seconds, which in turn modulates the accumulation of nitric oxide 5â¯min after treatment. At longer times, a biphasic accumulation of H2O2 with peaks at 2 and 5â¯h post treatment could be observed. In addition, HeT elicited the increase of alternative oxidase capacity during the first 12â¯h post treatment.
Assuntos
Cálcio/metabolismo , Fragaria/metabolismo , Peróxido de Hidrogênio/metabolismo , Taninos Hidrolisáveis/farmacologia , Óxido Nítrico/metabolismo , Sinalização do Cálcio , Eletrólitos/metabolismo , Fragaria/microbiologia , Doenças das Plantas/microbiologia , Xanthomonas/metabolismoRESUMO
In an incompatible interaction between Colletotrichum fragariae and strawberry plants, the accumulation of phenolic compounds in plant leaves was observed. A particularly abundant penta-esterified ellagitannin that accumulated in response to pathogen attack was identified as 1-0-galloyl-2,3;4,6-bis-hexahydroxydiphenoyl-ß-d-glucopyranose (HeT) by mass spectroscopy and nuclear magnetic resonance. Foliar application of purified HeT prior to inoculation with a virulent pathogen was shown to increase resistance toward C. acutatum in strawberry plants and to Xanthomonas citri subsp. citri in lemon plants. The induced resistance in strawberry was associated with a rapid oxidative burst, callose deposition, a transient increase of salicylic acid in phloem, and induction of gene expression responsive to salicylic acid. Results obtained suggested that HeT could be a common plant defense response molecule capable of inducing pathogen resistance in different plant species.
Assuntos
Fragaria/metabolismo , Fragaria/microbiologia , Taninos Hidrolisáveis/metabolismo , Taninos Hidrolisáveis/farmacologia , Citrus/metabolismo , Citrus/microbiologia , Colletotrichum/patogenicidade , Fragaria/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Floema/metabolismo , Ácido Salicílico/metabolismo , Xanthomonas/patogenicidadeRESUMO
El estudio se ha realizado en el Hospital Hipólito Unanue de Tacna entre octubre de 1996 y febrero de 1997. Se ha comprobado un número de 150 adolescentes embarazadas con sus respectivos grupos de control, formados por adultas embarazadas que se atendieron en el hospital, teniendo como objetivo principal determinar la actitud y el grado de aceptación del embarazo de las adolescentes en comparación con el de las adultas. Se ha demostrado que la edad de mayor incidencia del embarazo fluctúa entre los 17 y 19 años; y el grado de aceptación en la adolescente es de 46.0 por ciento. Cabe resaltar que la incidencia de embarazo en adolescentes en el período de octubre de 1996 y febrero 1997, fue de 19.4 por ciento.