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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.

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

Maize (Zea mays L.) is one of the most important crops in the world. It is the third most important food grain crop in the developing world and is estimated that the demand for maize in developing countries will grow by 50%, from 558 million tons in 1995 to 837 million tons in 2020. Much of this increased demand will be needed by domestic supply for developing countries, which will require intensifying production on existing agricultural land (Ribaut and Ragot, 2007). Drought is one of the prime abiotic stress in crops in the world. Crop yield losses due to drought stress are considerable. Particularly in maize, as an example, drought is the major stress affecting productivity in Africa leading up to 70% or total crop loss (Muoma et al., 2010; Ashraf, 2010). Although a variety of approaches have been used to alleviate the problem of drought, plant breeding, either conventional breeding or genetic engineering, seems to be an efficient and economic means of tailoring crops to enable them to grow successfully in drought-prone environments (Ashraf, 2010). In turn, aflatoxins are found to contaminate a wide variety of important agricultural products such as corn, peanuts, tree nuts and cottonseed especially under extreme heat and drought conditions (Payne, 1998; Chen et al., 2003). Aflatoxin contamination significantly reduces the value of grain as an animal feed and export commodity (Chen et al., 2002).