28 research outputs found

    Plant senescence and proteolysis: two processes with one destiny

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    Abstract Senescence-associated proteolysis in plants is a complex and controlled process, essential for mobilization of nutrients from old or stressed tissues, mainly leaves, to growing or sink organs. Protein breakdown in senescing leaves involves many plastidial and nuclear proteases, regulators, different subcellular locations and dynamic protein traffic to ensure the complete transformation of proteins of high molecular weight into transportable and useful hydrolysed products. Protease activities are strictly regulated by specific inhibitors and through the activation of zymogens to develop their proteolytic activity at the right place and at the proper time. All these events associated with senescence have deep effects on the relocation of nutrients and as a consequence, on grain quality and crop yield. Thus, it can be considered that nutrient recycling is the common destiny of two processes, plant senescence and, proteolysis. This review article covers the most recent findings about leaf senescence features mediated by abiotic and biotic stresses as well as the participants and steps required in this physiological process, paying special attention to C1A cysteine proteases, their specific inhibitors, known as cystatins, and their potential targets, particularly the chloroplastic proteins as source for nitrogen recycling

    An enigma in the genetic responses of plants to salt stresses

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    Soil salinity is one of the main factors restricting crop production throughout the world. Various salt tolerance traits and the genes controlling these traits are responsible for coping with salinity stress in plants. These coping mechanisms include osmotic tolerance, ion exclusion, and tissue tolerance. Plants exposed to salinity stress sense the stress conditions, convey specific stimuli signals, and initiate responses against stress through the activation of tolerance mechanisms that include multiple genes and pathways. Advances in our understanding of the genetic responses of plants to salinity and their connections with yield improvement are essential for attaining sustainable agriculture. Although a wide range of studies have been conducted that demonstrate genetic variations in response to salinity stress, numerous questions need to be answered to fully understand plant tolerance to salt stress. This chapter provides an overview of previous studies on the genetic control of salinity stress in plants, including signaling, tolerance mechanisms, and the genes, pathways, and epigenetic regulators necessary for plant salinity tolerance

    Macroeconomic effects of the minimum wage in Colombia

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    Utilizando enfoques de equilibrio parcial y equilibrio general, se estudian a fondo los efectos del salario mínimo en la macroeconomía colombiana. Con el primer enfoque, se analizan efectos en variables del mercado laboral, distribución de ingresos, desigualdad, pobreza monetaria de las familias, precios e inflación. Con el enfoque de equilibrio general se estudian los efectos en consumo, bienestar, producción, inversión, inflación y cuentas fiscales del gobierno. Según la evidencia, el salario mínimo tiene efectos negativos en casi todas las variables estudiadas, no permite un funcionamiento fluido del mercado laboral y no está cumpliendo con sus objetivos de contribuir a reducir la desigualdad y la pobreza. Se sugiere el rediseño de la implementación del salario mínimo en Colombia y de la forma como estamos capacitando nuestra mano de obra para elevar su productividad, de suerte que podamos llevar el salario mínimo en relación con el salario mediano de la economía, hoy en el 90%, a un nivel similar al de los países de la OECD, cercano al 50%.Using partial equilibrium and general equilibrium approaches, the effects of the minimum wage on the Colombian macroeconomy are thoroughly studied. With the first approach, the article analyzes the effects on variables of the labor market, income distribution, inequality, monetary poverty of families, prices, and inflation. With the general equilibrium approach, we study the effects on consumption, welfare, production, investment, inflation, and government fiscal accounts. According to the evidence, the minimum wage has negative effects on almost all the variables studied, it does not allow a fluid functioning of the labor market, and it is not fulfilling its objectives of contributing to reducing inequality and poverty. The redesign of the implementation of the minimum wage in Colombia and the way in which we are training our workforce to raise its productivity is suggested, so that we can bring the minimum wage in relation to the median wage of the economy, nowadays about 90 %, at a level similar to that of the OECD countries, close to 50%."Enfoque Al finalizar cada año, el país sigue un protocolo de negociación que conduce, por la vía del acuerdo entre las partes o, a falta de este, por decisión gubernamental, al aumento del salario mínimo. Pese a que se tiene evidencia de sus efectos adversos en el mercado laboral (empleo formal, desempleo e informalidad laboral), los incrementos suelen ser altos, con los argumentos de que un salario mínimo alto estimula la demanda agregada y tiene efectos redistributivos, sobre lo cual no se tiene mucha evidencia. Este documento estudia a fondo los efectos macroeconómicos del salario mínimo en Colombia. Utiliza enfoques de equilibrio parcial –y microdatos– para establecer su efecto en los flujos del mercado laboral (creación y destrucción de puestos de trabajo; contratación y separación de trabajadores) y el empleo formal, en la distribución de ingresos de los trabajadores y las familias, en desigualdad y pobreza monetaria de los hogares. Con este enfoque, también se provee evidencia sobre el efecto en los precios de bienes y servicios, en la inflación básica y en la inflación total.

    Reducing the acrylamide-forming potential of crop plants

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    Acrylamide is a food processing contaminant formed from free asparagine and reducing sugars during high-temperature cooking and processing. It is a Group 2A carcinogen, and EFSA’s CONTAM Panel has expressed concern for the potential tumour-inducing effects of dietary exposure. Fried, baked, roasted and toasted potato, coffee and cereal products are the major contributors to dietary acrylamide intake. The European Commission has recently introduced strengthened risk management regulations for acrylamide in food, including compulsory mitigation measures and new Benchmark Levels. Steps taken by manufacturers to reduce acrylamide formation in potato chips in Europe resulted in a 53 % decrease from 2002 to 2011. However, since 2011 there has been a levelling off, suggesting that the easy gains have already been made and further large reductions are unlikely. The acrylamide-forming potential of potatoes is influenced by seasonal and geographical factors, making regulatory compliance for potato products more difficult. In cereals, acrylamide formation is determined by free asparagine concentration: this differs substantially between varieties but is also very responsive to environmental factors and crop management. Ensuring good disease control and sulfur sufficiency are particularly important. The relationship between precursor concentration and acrylamide formation is more complex in potato, with the concentration of reducing sugars the more important parameter in most datasets but free asparagine concentration contributing to the variance. Storage is a key issue for potatoes due to the phenomena of cold and senescent sweetening. Investigations into the genetic control of acrylamide formation in wheat have focussed on asparagine metabolism, in particular asparagine synthetase, while biotech potatoes with reduced expression of asparagine synthetase and vacuolar invertase are already on the market in the USA
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