Molecular basis of salt tolerance in Physcomitrella Patens model plant: potassium homeostasis and physiological roles of chx transporters

El suelo salino impone un estrés abiótico importante que causa graves problemas en la agricultura ya que la mayoría de los cultivos se ven afectados por la salinidad debido a efectos osmóticos y tóxicos. Por ello, la contaminación y la escasez de agua dulce, la salinización progresiva de tierras y el aumento exponencial de la población humana representan un grave problema que amenaza la seguridad alimentaria mundial para las generaciones futuras. Por lo tanto, aumentar la tolerancia a la salinidad de los cultivos es un objetivo estratégico e ineludible para garantizar el suministro de alimentos en el futuro. Mantener una óptima homeostasis de K+ en plantas que sufren estrés salino es un objetivo importante en el proceso de obtención de plantas tolerantes a la salinidad. Aunque el modelo de la homeostasis de K+ en las plantas está razonablemente bien descrito en términos de entrada de K+, muy poco se sabe acerca de los genes implicados en la salida de K+ o de su liberación desde la vacuola. En este trabajo se pretende aclarar algunos de los mecanismos implicados en la homeostasis de K+ en plantas. Para ello se eligió la briofita Physcomitrella patens, una planta no vascular de estructura simple y de fase haploide dominante que, entre muchas otras cualidades, hacen que sea un modelo ideal. Lo más importante es que no sólo P. patens es muy tolerante a altas concentraciones de Na+, sino que también su posición filogenética en la evolución de las plantas abre la posibilidad de estudiar los cambios claves que, durante el curso de la evolución, se produjeron en las diversas familias de los transportadores de K+. Se han propuesto varios transportadores de cationes como candidatos que podrían tener un papel en la salida de K+ o su liberación desde la vacuola, especialmente miembros de la familia CPA2 que contienen las familias de transportadores KEA y CHX. En este estudio se intenta aumentar nuestra comprensión de las funciones de los transportadores de CHX en las células de las plantas usando P. patens, como ya se ha dicho. En esta especie, se han identificado cuatro genes CHX, PpCHX1-4. Dos de estos genes, PpCHX1 y PpCHX2, se expresan aproximadamente al mismo nivel que el gen PpACT5, y los otros dos genes muestran una expresión muy baja. La expresión de PpCHX1 y PpCHX2 en mutantes de Escherichia coli defectivos en el transporte de K+ restauraron el crecimiento de esta cepa en medios con bajo contenido de K+, lo que viii sugiere que la entrada de K+ es energizada por un mecanismo de simporte con H+. Por otra parte, estos transportadores suprimieron el defecto asociado a la mutación kha1 en Saccharomyces cerevisiae, lo que sugiere que podrían mediar un antiporte en K+/H+. La proteína PpCHX1-GFP expresada transitoriamente en protoplastos de P. patens co-localizó con un marcador de Golgi. En experimentos similares, la proteína PpCHX2-GFP localizó aparentemente en la membrana plasmática y tonoplasto. Se construyeron las líneas mutantes simples de P. patens ΔPpchx1 y ΔPpchx2, y también el mutante doble ΔPpchx2 ΔPphak1. Los mutantes simples crecieron normalmente en todas las condiciones ensayadas y mostraron flujos de entrada normales de K+ y Rb+; la mutación ΔPpchx2 no aumentó el defecto de las plantas ΔPphak1. En experimentos a largo plazo, las plantas ΔPpchx2 mostraron una retención de Rb+ ligeramente superior que las plantas silvestres, lo que sugiere que PpCHX2 promueve la transferencia de Rb+ desde la vacuola al citosol o desde el citosol al medio externo, actuando en paralelo con otros transportadores. Sugerimos que transportadores de K+ de varias familias están involucrados en la homeostasis de pH de orgánulos ya sea mediante antiporte K+/H+ o simporte K+-H+.ix ABSTRACT Soil salinity is a major abiotic stress causing serious problems in agriculture as most crops are affected by it. Moreover, the contamination and shortage of freshwater, progressive land salinization and exponential increase of human population aggravates the problem implying that world food security may not be ensured for the next generations. Thus, a strategic and an unavoidable goal would be increasing salinity tolerance of plant crops to secure future food supply. Maintaining an optimum K+ homeostasis in plants under salinity stress is an important trait to pursue in the process of engineering salt tolerant plants. Although the model of K+ homeostasis in plants is reasonably well described in terms of K+ influx, very little is known about the genes implicated in K+ efflux or release from the vacuole. In this work, we aim to clarify some of the mechanisms involved in K+ homeostasis in plants. For this purpose, we chose the bryophyte plant Physcomitrella patens, a nonvascular plant of simple structure and dominant haploid phase that, among many other characteristics, makes it an ideal model. Most importantly, not only P. patens is very tolerant to high concentrations of Na+, but also its phylogenetic position in land plant evolution opens the possibility to study the key changes that occurred in K+ transporter families during the course of evolution. Several cation transporter candidates have been proposed to have a role in K+ efflux or release from the vacuole especially members of the CPA2 family which contains the KEA and CHX transporter families. We intended in this study to increase our understanding of the functions of CHX transporters in plant cells using P. patens, in which four CHX genes have been identified, PpCHX1-4. Two of these genes, PpCHX1 and PpCHX2, are expressed at approximately the same level as the PpACT5 gene, but the other two genes show an extremely low expression. PpCHX1 and PpCHX2 restored growth of Escherichia coli mutants on low K+-containing media, suggesting they mediated K+ uptake that may be energized by symport with H+. In contrast, these genes suppressed the defect associated to the kha1 mutation in Saccharomyces cerevisiae, which suggest that they might mediate K+/H+ antiport. PpCHX1-GFP protein transiently expressed in P. patens protoplasts co-localized with a Golgi marker. In similar experiments, the PpCHX2-GFP protein appeared to localize to tonoplast and plasma x membrane. We constructed the ΔPpchx1 and ΔPpchx2 single mutant lines, and the ΔPpchx2 ΔPphak1 double mutant. Single mutant plants grew normally under all the conditions tested and exhibited normal K+ and Rb+ influxes; the ΔPpchx2 mutation did not increase the defect of ΔPphak1 plants. In long-term experiments, ΔPpchx2 plants showed a slightly higher Rb+ retention than wild type plants, which suggests that PpCHX2 mediates the transfer of Rb+ from either the vacuole to the cytosol or from the cytosol to the external medium in parallel with other transporters. We suggest that K+ transporters of several families are involved in the pH homeostasis of organelles by mediating either K+/H+ antiport or K+-H+ symport.

Comparison of different pre-treatments to improve accuracy of total soluble solids.

The applicability of a portable NIR spectrometer for estimating the °Brix content of grapes by non-destructive measurement has been analysed in field. The NIR spectrometer AOTF-NIR Luminar 5030, from Brimrose, was used. The spectrometer worked with a spectral range from 1100 to 2300 nm. A total of 600 samples of Cabernet Sauvignon grapes, belonging to two vintages, were measured in a non-destructive way. The specific objective of this research is to analyse the influence of the statistical treatment of the spectra information in the development of °Brix estimation models. Different data pretreatments have been tested before applying multivariate analysis techniques to generate estimation models. The calibration using PLS regression applied to spectra data pretreated with the MSC method (multiplicative scatter correction) has been the procedure with better results. Considering the models developed with data corresponding to the first campaign, errors near to 1.35 °Brix for calibration (SEC = 1.36) and, about 1.50 °Brix for validation (SECV = 1.52) were obtained. The coefficients of determination were R2 = 0.78 for the calibration, and R2 = 0.77 for the validation. In addition, the great variability in the data of the °Brix content for the tested plots was analysed. The variation of °Brix on the plots was up to 4 °Brix, for all varieties. This deviation was always superior to the calculated errors in the generated models. Therefore, the generated models can be considered to be valid for its application in field. Models were validated with data corresponding to the second campaign. In this sense, the validation results were worse than those obtained in the first campaign. It is possible to conclude in the need to realize an adjustment of the spectrometer for each season, and to develop specific predictive models for every vineyard.

Economic impacts of climate change on agrifood markets: A bio-economic approach with a focus on the EU

Projections for world food production and prices play a crucial role to evaluate and tackle future food security challenges. Understanding how these projections will be affected by climate change is the main objective of this study. By means of a bio-economic approach we assess the economic impacts of climate change on agrifood markets, providing both a global analysis and a regionalised evaluation within the EU. To account for uncertainty, we analyse the IPCC emission scenario A1B for the 2030 horizon under several simulation scenarios that differ in (1) the climate projection, from HadleyCM3 (warm) or ECHAM5 (mild) global circulation models; and (2) the influence of CO2 effects. Results of this study indicate that agrifood market projections to 2030 are very sensitive to climate change uncertainties and, in particular to the magnitude of the carbon fertilization effect.

Identifying Factor Productivity from Micro-data: The case of EU agriculture. Factor Markets Working Paper No. 34, January 2013

The classical problem of agricultural productivity measurement has regained interest owing to recent price hikes in world food markets. At the same time, there is a new methodological debate on the appropriate identification strategies for addressing endogeneity and collinearity problems in production function estimation. We examine the plausibility of four established and innovative identification strategies for the case of agriculture and test a set of related estimators using farm-level panel datasets from seven EU countries. The newly suggested control function and dynamic panel approaches provide attractive conceptual improvements over the received ‘within’ and duality models. Even so, empirical implementation of the conceptual sophistications built into these estimators does not always live up to expectations. This is particularly true for the dynamic panel estimator, which mostly failed to identify reasonable elasticities for the (quasi-) fixed factors. Less demanding proxy approaches represent an interesting alternative for agricultural applications. In our EU sample, we find very low shadow prices for labour, land and fixed capital across countries. The production elasticity of materials is high, so improving the availability of working capital is the most promising way to increase agricultural productivity.

Vegetable outlook & situation /

Mode of access: Internet.

Fruit outlook & situation /

"Approved by the World Food and Agricultural Outlook and Situation Board."--P. 3.

Agricultural supply & demand estimates.

"Approved by the World Food and Agricultural Outlook and Situation Board."

Foreign agriculture circular.

Mode of access: Internet.

Weekly weather and crop bulletin /

Latest issue consulted: Vol. 85, no. 30 (July 28, 1998).

Outlook & situation.

" Approved by the World Food and Agricultural Outlook and Situation Board."--P. 3.

Feed situation.

Cover title.

Strategies for agricultural change and the UK balance of payments

The world food crisis, Britain's reliance on imported food and feedstuffs and balance of payments difficulties were some of the factors which lent weight to the call for increased self-sufficiency in Britain's agriculture in the 1970s. This project considers two main areas: an investigation of the impact of radical agricultural change, designed to increase self-sufficiency, on the balance of payments; and, an appraisal of the potential role of the food industry within a radically different food system. The study proceeded by: an examination of the principles of agricultural policy and its development in Britain; an overview of the mechanism and meaning of the balance of payments; a consideration of the debate on agricultural import saving; the construction of radical agricultural strategies; the estimation of effects of the strategies, particularly to the balance of. payments; the role of the food industry and possible innovations within the strategies; a case study of textured vegetable proteins; and, the wider implications of implementation of radical agricultural alternatives. Two strategies were considered: a vegan system, involving no livestock; and, an intermediate system, including some livestock and dairy cattle. The study concludes that although agricultural change could in principle make a contribution to the balance of payments, implementation of agricultural change cannot be justified for this purpose alone. First, balance of payments problems can be solved by more appropriate methods. Second, the UK' s balance of payments problem has disappeared for the time being owing to North Sea oil and economic recession. Third, the political and social consequences of the changes investigated would be unacceptable. Progress in UK food policy is likely to be in the form of an integrated food and health policy.

A review of weed management in wheat using crop competition

Wheat occupies a principal place in the diet of humans globally, contributing more to our daily calorie and protein intake than any other crop. For this reason, preventing weed induced yield losses in wheat has high significance for world food sustainability. Herbicides and tillage play an important role in weed control, but their use has often unacceptable consequences for humans and the wider environment. Additionally, the range of herbicides effective on key weeds is dwindling due to the evolution of herbicide resistance. Elevating crop competitiveness against weeds, through a combination of wheat breeding and innovative planting design (planting density, row spacing and orientation), has strong potential to reduce weed-induced yield losses in wheat. The last decade of research has provided a solid foundation for the breeding of weed suppressive wheat cultivars, and continued research in this area should be a focus for the future. In the interim, there is cause for optimism that weeds can be effectively suppressed using existing wheat varieties, through careful cultivar selection and choice of planting design. Further research is required to define the nature of relationships between cultivar traits and competitive planting strategies, across diverse weed flora in multiple countries, sites and seasons. Investment in such innovation promises to produce benefits, not only in terms of sustained wheat yields, but also in terms of human and ecosystem health, through ameliorating chemical and sediment contamination, soil degradation, and CO2 pollution.

CRISIS ALIMENTARIA: NUEVO MEGA-NEGOCIO GLOBAL

Resumen El presente artículo desenmascara la forma en que falazmente las instituciones financieras multilaterales pretenden hacer ver las causas de lo que han dado en llamar “la crisis alimentaria mundial” a partir del incremento de los precios de los alimentos alrededor del mundo. Agrocombustibles, incremento del precio del petróleo, cambio climático en zonas productoras son algunas de las causas que el Banco Mundial pone como justificación al incremento del precio de la mayoría de cereales y granos básicos. La milagrosa solución al hambre en los países pobres: la minería, es lanzada desde este todopoderoso agente financiero, como panacea para la producción de regalías que permitan a muchos países de África y algunos de América Latina y Asia,  para resolver la problemática alimentaria.  ¡Nada más falso! En los siguientes párrafos se describen las verdaderas razones de la crisis del actual modelo económico mundial, y se proponen desde un país en concreto,  propuestas de política pública para su solución.   Abstract The present article unmasks the way in which multilateral financial institutions pretend fallaciously to show the causes of which they have given to call “the world food crisis” since the increasing prices of food around the world. Agrofuels, increase the price of oil, produces climate chance in zones used for production, these are some of the causes that the World Bank uses to justify the increasing prices of the majority of cereals and grains. The miraculous solution for hunger in poor countries: mining, is launched from this all mighty financial agent, as a panacea to produce royalties that will permit many countries in Africa, and in some in Latin American and Asia, to solve their food problematic. Nothing more false than that! In the next paragraphs the true reasons of this crisis of the actual economic world model are described, and from a particular country, proposals of public politics for their solutions.

Gastrodiplomacia como herramienta de política exterior. estudio de caso: Perú

El presente trabajo tiene como objetivo analizar la manera mediante la cual Perú ha incor- porado la gastrodiplomacia a su estrategia de diplomacia cultural como componente de su política exterior. Con el fin de cumplir este propósito, se va a defender que desde el 2008 el país Inca ha incorporado la gastrodiplomacia a su estrategia de diplomacia cultural em- pleando dos herramientas. Primero, a través de su Plan de Política Exterior Cultural, en donde se señalan objetivos claros en temas de gastronomía. En segundo lugar, con el uso de su marca país mediante la cual se promociona al Perú como un país atractivo gracias a su amplia oferta gastronómica. El trabajo es de carácter analítico y descriptivo ya que pretende entender la manera en la que Perú incorporó la gastrodiplomacia en su política exterior y describir esos objetivos y características de su Plan de Política Exterior Cultural y de su estrategia de marca país.