A Single Amino-Acid Substitution in the Sodium Transporter HKT1 Associated with Plant Salt Tolerance

A crucial prerequisite for plant growth and survival is the maintenance of potassium uptake, especially when high sodium surrounds the root zone. The Arabidopsis HIGH-AFFINITY K(+) TRANSPORTER1 (HKT1), and its homologs in other salt-sensitive dicots, contributes to salinity tolerance by removing Na(+) from the transpiration stream. However, TsHKT1;2, one of three HKT1 copies in Thellungiella salsuginea, a halophytic Arabidopsis relative, acts as a K(+) transporter in the presence of Na(+) in yeast (Saccharomyces cerevisiae). Amino-acid sequence comparisons indicated differences between TsHKT1;2 and most other published HKT1 sequences with respect to an Asp residue (D207) in the second pore-loop domain. Two additional T salsuginea and most other HKT1 sequences contain Asn (n) in this position. Wild-type TsHKT1;2 and altered AtHKT1 (AtHKT1(N-D)) complemented K(+)-uptake deficiency of yeast cells. Mutant hkt1-1 plants complemented with both AtHKT1(N) (-) (D) and TsHKT1;2 showed higher tolerance to salt stress than lines complemented by the wild-type AtHKT1 Electrophysiological analysis in Xenopus laevis oocytes confirmed the functional properties of these transporters and the differential selectivity for Na(+) and K(+) based on the n/d variance in the pore region. This change also dictated inward-rectification for Na(+) transport. Thus, the introduction of Asp, replacing Asn, in HKT1-type transporters established altered cation selectivity and uptake dynamics. We describe one way, based on a single change in a crucial protein that enabled some crucifer species to acquire improved salt tolerance, which over evolutionary time may have resulted in further changes that ultimately facilitated colonization of saline habitats

Ozone Damages to Italian Crops: Environmental Constraints

The main environmental features of Italian cropping systems are described with particular emphasis on their effects on crop responses to ozone pollution. High ozone levels have been recorded all over Italy and daily patterns show, at nighttimes, strong decreases in plain areas, while ozone levels remain high in hilly areas. In the latter sites, therefore, the contribution of nocturnal stomatal conductance (gsto) to ozone uptake should be further studied. It is well known that summer drought and soil salinity reduce the soil water potential, thus causing gsto to decrease. These are likely to be the most important factors reducing crop gas-exchange and yield under environmental conditions occurring in Italy. However, the stressinduced reduction of gsto also restricts ozone uptake and, consequently, its potential damage. In Southern Italy, gasexchange limitations have been also measured in irrigated crops between two successive irrigations. Finally, the effect of water stagnation, which often occurs in clay soils of southern Italy, should be not underestimated. In these soils, in fact, root anoxia will cause stomatal closure and, consequently, will also interfere with ozone uptake and damage

Multiple benefits of legumes for agriculture sustainability: an overview

Food security, lowering the risk of climate change and meeting the increasing demand for energy will increasingly be critical challenges in the years to come. Producing sustainably is therefore becoming central in agriculture and food systems. Legume crops could play an important role in this context by delivering multiple services in line with sustainability principles. In addition to serving as fundamental, worldwide source of high-quality food and feed, legumes contribute to reduce the emission of greenhouse gases, as they release 5–7 times less GHG per unit area compared with other crops; allow the sequestration of carbon in soils with values estimated from 7.21 g kg−1 DM, 23.6 versus 21.8 g C kg−1 year; and induce a saving of fossil energy inputs in the system thanks to N fertilizer reduction, corresponding to 277 kg ha−1 of CO2 per year. Legumes could also be competitive crops and, due to their environmental and socioeconomic benefits, could be introduced in modern cropping systems to increase crop diversity and reduce use of external inputs. They also perform well in conservation systems, intercropping systems, which are very important in developing countries as well as in low-input and low-yield farming systems. Legumes fix the atmospheric nitrogen, release in the soil high-quality organic matter and facilitate soil nutrients' circulation and water retention. Based on these multiple functions, legume crops have high potential for conservation agriculture, being functional either as growing crop or as crop residue. Open image in new window Graphical abstract

Drone and sensor technology for sustainable weed management: a review

Weeds are amongst the most impacting abiotic factors in agriculture, causing important yield loss worldwide. Integrated Weed Management coupled with the use of Unmanned Aerial Vehicles (drones), allows for Site-Specific Weed Management, which is a highly efficient methodology as well as beneficial to the environment. The identification of weed patches in a cultivated field can be achieved by combining image acquisition by drones and further processing by machine learning techniques. Specific algorithms can be trained to manage weeds removal by Autonomous Weeding Robot systems via herbicide spray or mechanical procedures. However, scientific and technical understanding of the specific goals and available technology is necessary to rapidly advance in this field. In this review, we provide an overview of precision weed control with a focus on the potential and practical use of the most advanced sensors available in the market. Much effort is needed to fully understand weed population dynamics and their competition with crops so as to implement this approach in real agricultural contexts

Sustainable food security: an emerging research and policy agenda

As a response to emerging calls for the adoption of a systemic approach to food security, in this article we identify and discuss inextricably linked barriers to ‘sustainable food security’. Based on an extensive analysis of recent academic and policy literatures on the economic, social and ecological effects of global environmental change at different stages of the food system, we highlight a series of cross-cutting issues and areas of disconnection between food production and consumption that call for a renovated focus on the different nodal points of the food system. As we suggest, a sustainable food security framework should move away from the conventional focus on individual components of the food system (e.g., supply and demand) and address more holistically the complex relationships between its different stages and actors

the role of biostimulants and bioeffectors as alleviators of abiotic stress in crop plants

Abstract The use of bioeffectors, formally known as plant biostimulants, has become common practice in agriculture and provides a number of benefits in stimulating growth and protecting against stress. A biostimulant is loosely defined as an organic material and/or microorganism that is applied to enhance nutrient uptake, stimulate growth, enhance stress tolerance or crop quality. This review is intended to provide a broad overview of known effects of biostimulants and their ability to improve tolerance to abiotic stresses. Inoculation or application of extracts from algae or other plants have beneficial effects on growth and stress adaptation. Algal extracts, protein hydrolysates, humic and fulvic acids, and other compounded mixtures have properties beyond basic nutrition, often enhancing growth and stress tolerance. Non-pathogenic bacteria capable of colonizing roots and the rhizosphere also have a number of positive effects. These effects include higher yield, enhanced nutrient uptake and utilization, increased photosynthetic activity, and resistance to both biotic and abiotic stresses. While most biostimulants have numerous and diverse effects on plant growth, this review focuses on the bioprotective effects against abiotic stress. Agricultural biostimulants may contribute to make agriculture more sustainable and resilient and offer an alternative to synthetic protectants which have increasingly falling out of favour with consumers. An extensive review of the literature shows a clear role for a diverse number of biostimulants that have protective effects against abiotic stress but also reveals the urgent need to address the underlying mechanisms responsible for these effects. Graphical abstract Biostimulants have protective effects against abiotic stress

Anthocyanins are Key Regulators of Drought Stress Tolerance in Tobacco

Abiotic stresses will be one of the major challenges for worldwide food supply in the near future. Therefore, it is important to understand the physiological mechanisms that mediate plant responses to abiotic stresses. When subjected to UV, salinity or drought stress, plants accumulate specialized metabolites that are often correlated with their ability to cope with the stress. Among them, anthocyanins are the most studied intermediates of the phenylpropanoid pathway. However, their role in plant response to abiotic stresses is still under discussion. To better understand the effects of anthocyanins on plant physiology and morphogenesis, and their implications on drought stress tolerance, we used transgenic tobacco plants (AN1), which over-accumulated anthocyanins in all tissues. AN1 plants showed an altered phenotype in terms of leaf gas exchanges, leaf morphology, anatomy and metabolic profile, which conferred them with a higher drought tolerance compared to the wild-type plants. These results provide important insights for understanding the functional reason for anthocyanin accumulation in plants under stress

NPK: Will there be enough plant nutrients to feed a world of 9 billion in 2050?

Will there be enough plant nutrients to feed a world of 9 billion in 2050? is the central question addressed by a JRC study. This exercise was based on consultations with experts and a thematic workshop focused on three areas of interest: 1) the demand for fertilizers to sustain crop production necessary to feed the world in 2050; 2) perspectives on the supply of Nitrogen (N), Phosphorus (P) and Potassium (K) to world agriculture and 3) the role of innovation and technology in changing the match between demand and supply of fertilizers. Implications of the main findings for current EU and international policies were addressed. Overall, analysis of existing literature and discussions with major experts and stakeholders led to the conclusion that while the situation is currently not critical with respect to the production and availability of plant nutrients, it is important to remain vigilant. The question of reserves (P and K), access, changing geopolitical conditions, economic development, energy costs (mainly for N) and environmental constraints (N and P) could lead to shortfalls and possibly crisis situations in some regions of the world. The situation of Africa deserves particular attention as production, access and use of fertilizers represent key limiting factors in boosting food production in that continent.JRC.A.1-Science Advice to Polic

Fertilisation with compost mitigates salt stress in tomato by affecting plant metabolomics and nutritional profiles

Abstract Background Salinity is one of the major threats for crop growth and yield and its rate of expansion is expected to increase. We conducted a pot experiment to evaluate and compare the effect of a green compost addition and mineral fertilisation, on growth, nutrition and metabolites of tomato plants, exposed to increasing doses of NaCl. Results Although the development of stressed plants was lower than the corresponding controls, compost-treated plants performed better than mineral-amended plants watered with the same amount of salt. The different plant growth was related to an increased nutritional status. Namely, compost-treated plants showed a larger content of macro- and micronutrients, and a greater accumulation of osmoprotectants, such as soluble sugars and amino acids. Moreover, compost-treated plants showed a larger content of metabolites involved in modulating the response to salt stress, such as molecules related to energy transfer in plants and precursors of Reactive Oxygen Species scavenging compounds. Overall, the better performance of compost-added plants may be attributed to a greater availability of the organic forms of nutrients and to the positive bioactivity of compost-derived humic substances. Conclusions Compost application efficiently mitigated salt stress in tomato plants in respect to mineral fertilisation. This alleviating role was associated to the induction of a more efficient metabolic response that increased accumulation of metabolites involved in modulating the salinity stress. Therefore, fertilising with composted agricultural residue may represent a convenient alternative to mineral fertilisers to grow tomato plants in the presence of salt stress. Graphical Abstrac