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Hydrogen peroxide is an important signal molecule in plant defense against biotic and abiotic stress. Pepper golden mosaic virus (PepGMV) is a whitefly-transmitted geminivirus causing significant yield and quality losses in pepper and other horticultural crops in Mexico. Several pesticides have been used trying to control whiteflies and thus, PepGMV disease in host crops. The present work examined the effect of exogenous application of hydrogen peroxide (H2O2) on inducing resistance to PepGMV infection in pepper plants. Experiments were carried out under greenhouse conditions aiming to evaluate phenotypical, biochemical and molecular features in these pepper plants. Hydrogen peroxide at 6, 14 and 18 mM induced tolerance to PepGMV either by absence of symptoms as well as by attenuating and/or delaying them. The protection observed was directly dependent on the concentration of H2O2 sprayed on plants. Moreover, PepGMV DNA levels were inversely proportional to the protection level. Enzymatic and gene expression profiles related with plant defense were induced in protected, in comparison to susceptible control plants. Interestingly, the levels of some phenolic compounds were also associated with plant protection. Taking together, these results suggested that exogenous foliar applications of H2O2 protect pepper plants against PepGMV infection inducing the plant host defense arsenal.

Hydrogen peroxide (H2O2) is an important ROS molecule (Reactive oxygen species) that serves as a signal of oxidative stress and activation of signaling cascades as a result of the early response of the plant to biotic stress. This response can also be generated with the application of elicitors, stable molecules that induce the activation of transduction cascades and hormonal pathways, which trigger induced resistance to environmental stress. In this work, we evaluated the endogenous H2O2 production caused by salicylic acid (SA), chitosan (QN), and H2O2 elicitors in Capsicum annuum L. Hydrogen peroxide production after elicitation, catalase (CAT) and phenylalanine ammonia lyase (PAL) activities, as well as gene expression analysis of cat1, pal, and pathogenesis-related protein 1 (pr1) were determined. Our results displayed that 6.7 and 10 mM SA concentrations, and, 14 and 18 mM H2O2 concentrations, induced an endogenous H2O2 and gene expression. QN treatments induced the same responses in lesser proportion than the other two elicitors. Endogenous H2O2 production monitored during several days, showed results that could be an indicator for determining application opportunity uses in agriculture for maintaining plant alert systems against a stress.

Modifications in growing techniques can affect the yield and nutritional quality of various cultivated plant species. Owing to its high nutritional value, sweet pepper (Capsicum annuum L.) was used in this study as a model plant to investigate the effect of abiotic stress (Electrical conductivity [EC]) and elicitor (Salicylic acid [SA]) on yield and fruit quality parameters under conditions of greenhouse. Nonetheless, the application of elicitors, are stable molecules that induce the activation of transduction cascades and hormonal pathways, which trigger induced resistance to environmental stress. The combination in metabolomics of advanced analytical methods and bioinformatics tools provides wide chemical compositional data that contributes to corroborate (or not) the substantial equivalence. The aim was evaluated the endogenous H2O2 production caused by the effect of different concentrations of (SA) in Capsicum annuum L. in production after elicitation in seedling, and the production of secondary metabolites using GC-MS (flavonoids, tannins and phenolic content as well as the antioxidant properties) in plant and fruit of Capsicum annuum L. to relate their response in metabolic pathways. Results displayed that the use SA, induced an endogenous H2O2 and enzymatic activities related with plant defense as phenylalanine ammonia lyase and catalase. This production showed results that could be an indicator for determining application opportunity uses in agriculture for maintaining plant alert systems against a stress. These results were correlated with those obtained from cultivation of capsicum annum until obtaining the fruit at ripe stage had a high content of bioactive compounds that exhibited significant antioxidant properties. The correlation of the contents of flavonoids, tannins and total phenolics and the ability to remove free radicals of the sweet pepper was significant (r = 0.99, P

Capsaicinoids are plant secondary metabolites, capsaicin being the principal responsible for the pungency of chili peppers. It is biosynthesized through two pathways involved in phenylpropanoid and fatty acid metabolism. Plant capsaicin concentration is mainly affected by genetic, environmental and crop management factors. However, its synthesis can be enhanced by the use of elicitors. Capsaicin is employed as food additive and in pharmaceutical applications. Additionally, it has been found that capsaicin can act as a cancer preventive agent and shows wide applications against various types of cancer. This review is an approach in contextualizing the use of controlled stress on the plant to increase the content of capsaicin, highlighting its synthesis and its potential use as anticancer agent.

The Geminiviruses genome is a small, single strand DNA that replicates in the plant cell nucleus. Analogous to animal DNA viruses, Geminiviruses depend on the host replication machinery to amplify their genomes and only supply the factors required to initiate their replication. Consequently, Geminiviruses remove the cell-cycle arrest and induce the host replication machinery using an endocycle process. They encode proteins, such as the conserved replication-associated proteins (Rep) that interact with retinoblastoma-like proteins in plants and alter the cell division cycle in yeasts. Therefore, the aim of this work is to analyze the impact of Pepper Golden Mosaic Virus (PepGMV) Rep protein in mammalian cells. Results indicate that the pTracer-SV40:Rep construction obtained in this work can be used to analyze the Rep protein effect in mammalian cells in order to compare the cell cycle regulation mechanisms in plants and animals.

Fungi play a very important, but yet mostly unexplored role. Their widespread occurrence on land and in marine life makes them a challenge and a risk for humans (Brase et al., 2009). Fungi are ingenious producers of complex natural products which show a broad range of biological activities (Bohnert et al., 2010). However, a specific characteristic is the production of toxins. Mycotoxins (from “myco” fungus and toxin), are nonvolatile, relatively low-molecular weight, fungal secondary metabolic products (Brase et al., 2009). The most agriculturally important micotoxins are aflatoxins (AF) which are a group of highly toxic metabolites, studied primarly because of their negative effects on human health. Aflatoxins belong to a group of difuranocumarinic derivatives structurally related, and are produced meanly by fungi of genus Aspergillus spp. Its production depends on many factors such as substrate, temperature, pH, relative humidity and the presence of other fungi. It has been identified 18 types of aflatoxins; the most frequent in foods are B1, B2, G1, G2, M1, and M2 (Bhatnagar et al., 2002). These secondary metabolites contaminate a number of oilseed crops during growth of the fungus and this can result in severe negative economic and health impacts (Cary et al., 2009). The higher levels of aflatoxins have been found in cotton and maize seeds, peanuts, and nuts. In grains like wheat, rice, rye or barley the presence of aflatoxins is less frequent. Mycotoxins may also occur in conjugated form, either soluble (masked mycotoxins) or incorporated into/ associated with/attached to macromolecules (bound mycotoxins). These conjugated mycotoxins can emerge after metabolization by living plants, fungi and mammals or after food processing. Awareness of such altered forms of mycotoxins is increasing, but reliable analytical methods, measurement standards, occurrence, and toxicity data are still lacking (Berthiller et al., 2009). A variety of studies has been conducted in order to understand the process of crop contamination by aflatoxins. Mycotoxins are dangerous metabolites that are often carcinogenic, and they represent a serious threat to both animal and human health (Reverberi et al., 2010). Mycotoxins are considered secondary metabolites because