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Leprosy, caused by Mycobacterium leprae, has plagued humanity for thousands of years and continues to cause morbidity, disability and stigmatization in two to three million people today. Although effective treatment is available, the disease incidence has remained approximately constant for decades so new approaches, such as vaccine or new drugs, are urgently needed for control. Research is however hampered by the pathogen's obligate intracellular lifestyle and the fact that it has never been grown in vitro. Consequently, despite the availability of its complete genome sequence, fundamental questions regarding the biology of the pathogen, such as its metabolism, remain largely unexplored. In order to explore the metabolism of the leprosy bacillus with a long-term aim of developing a medium to grow the pathogen in vitro, we reconstructed an in silico genome scale metabolic model of the bacillus, GSMN-ML. The model was used to explore the growth and biomass production capabilities of the pathogen with a range of nutrient sources, such as amino acids, glucose, glycerol and metabolic intermediates. We also used the model to analyze RNA-seq data from M. leprae grown in mouse foot pads, and performed Differential Producibility Analysis to identify metabolic pathways that appear to be active during intracellular growth of the pathogen, which included pathways for central carbon metabolism, co-factor, lipids, amino acids, nucleotides and cell wall synthesis. The GSMN-ML model is thereby a useful in silico tool that can be used to explore the metabolism of the leprosy bacillus, analyze functional genomic experimental data, generate predictions of nutrients required for growth of the bacillus in vitro and identify novel drug targets.

Blueberry (Vaccinium corymbosum L.) continues to gain importance in the international market due to its effects on the prevention of human diseases. This leads to the need to optimize the production and quality of the fruit. The present research evaluated the effect of NO3- and NH4+, using the split roots technique, in the nutritional status, photosynthetic pigments and total sugars in blueberry leaves. A completely random experiment was established with six greenhouse treatments: three under homogeneous root conduction (HR) and three with split roots (SR). The concentration of N, P, K, Ca, Mg, S, Fe, Cu, Zn, Mn, B and Na, chlorophyll a (Chl a), chlorophyll b (Chl b), carotenoids (Car) and total sugars were evaluated in the leaves. The exclusive supply of NH4+ led to the largest accumulation of N, P, Mg, S, Cu, Mn and B, compared to plants treated with NO3-. The Chla and total sugars were higher with NH4+ compared to NO3- nutrition. The supply of N separately (SR) had no positive effects on the evaluated variables, however, the SR with half of N, in the form of NH4+, compared to the non-SR with full application of N, has no differences in N-leaf concentration, which implies a higher use in the uptake or accumulation of this macro element in plant. V. corymbosum L. with split root and half of N in the form of NH4+, doubled the N use efficiency, as it matches in yield the complete supply treatment of N-NH4+ without root division.

Climate change scenarios forecast increased aridity in large areas worldwide with potentially important effects on nutrient availability and plant growth. Plant nitrogen and phosphorus concentrations (plant [N] and [P]) have been used to assess nutrient limitation, but a comprehensive understanding of drought stress on plant [N] and [P] remains elusive. We conducted a meta‐analysis to examine responses of plant [N] and [P] to drought manipulation treatments and duration of drought stress. Drought stress showed negative effects on plant [N] (−3.73%) and plant [P] (−9.18%), and a positive effect on plant N : P (+ 6.98%). Drought stress had stronger negative effects on plant [N] and [P] in the short term (< 90 d) than in the long term (> 90 d). Drought treatments that included drying–rewetting cycles showed no effect on plant [N] and [P], while constant, prolonged, or intermittent drought stress had a negative effect on plant [P]. Our results suggest that negative effects on plant [N] and [P] are alleviated with extended duration of drought treatments and with drying–rewetting cycles. Availability of water, rather than of N and P, may be the main driver for reduced plant growth with increased long‐term drought stress.

Arbuscular mycorrhizal symbiosis occurs between obligate biotrophic fungi of the phylum Glomeromycota and most of land plants. The exchange of nutrients between host plants and arbuscular mycorrhizal fungi is presumed to be the main benefit for the two symbiotic partners. In this review article, we outline the current concepts of nutrient exchanges within this symbiosis (mechanisms and regulation). First, we focus on phosphorus and nitrogen transfer from the fungal partner to the host plant and on the reciprocal transfer of carbon compounds, with a highlight on a possible interplay between nitrogen and phosphorus nutrition during arbuscular mycorrhizal symbiosis. We further discuss potential mechanisms of regulation of these nutrient exchanges linked to membrane dynamics. The review finally addresses the common mycorrhizal networks formed by arbuscular mycorrhizal fungi, which inter-connect plants from similar and/or different species. Then the best way to integrate this knowledge and the ensuing potential benefits of arbuscular mycorrhiza in a sustainable agriculture is discussed. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

• Understanding how plant species influence soil nutrient cycling is a major theme in terrestrial ecosystem ecology. However, the prevailing paradigm has mostly focused on litter decomposition, while rhizosphere effects on soil organic matter (SOM) decomposition have attracted little attention. • Using a dual 13C/15N labeling approach in a ‘common garden’ glasshouse experiment, we investigated how the economic strategies of 12 grassland plant species (graminoids, forbs and legumes) drive soil nitrogen (N) cycling via rhizosphere processes, and how this in turn affects plant N acquisition and growth. • Acquisitive species with higher photosynthesis, carbon rhizodeposition and N uptake than conservative species induced a stronger acceleration of soil N cycling through rhizosphere priming of SOM decomposition. This allowed them to take up larger amounts of N and allocate it above ground to promote photosynthesis, thereby sustaining their faster growth. The N₂-fixation ability of legumes enhanced rhizosphere priming by promoting photosynthesis and rhizodeposition. • Our study demonstrates that the economic strategies of plant species regulate a plant–soil carbon–nitrogen feedback operating through the rhizosphere. These findings provide novel mechanistic insights into how plant species with contrasting economic strategies sustain their nutrition and growth through regulating the cycling of nutrients by soil microbes in their rhizosphere.

• Root exudation stimulates microbial decomposition and enhances nutrient availability to plants. It remains difficult to measure and predict this carbon flux in natural conditions, especially for mature woody plants. Based on a known conceptual framework of root functional traits coordination, we proposed that root functional traits may predict root exudation. • We measured root exudation and other seven root morphological/chemical/physiological traits for 18 coexisting woody species in a deciduous-evergreen mixed forest in subtropical China. • Root exudation, respiration, diameter and nitrogen (N) concentration all exhibited significant phylogenetic signals. We found that root exudation positively correlated with competitive traits (root respiration, N concentration) and negatively with a conservative trait (root tissue density). Furthermore, these relationships were independent of phylogenetic signals. A principal component analysis showed that root exudation and morphological traits loaded on two perpendicular axes. • Root exudation is a competitive trait in a multidimensional fine-root functional coordination. The metabolic dimension on which root exudation loaded was relatively independent of the morphological dimension, indicating that increasing nutrient availability by root exudation might be a complementary strategy for plant nutrient acquisition. The positive relationship between root exudation and root respiration and N concentration is a promising approach for the future prediction of root exudation.

• Nutrient distribution and neighbours can impact plant growth, but how neighbours shape root-foraging strategy for nutrients is unclear. Here, we explore new patterns of plant foraging for nutrients as affected by neighbours to improve nutrient acquisition. • Maize (Zea mays) was grown alone (maize), or with maize (maize/maize) or faba bean (Vicia faba) (maize/faba bean) as a neighbour on one side and with or without a phosphorus (P)-rich zone on the other in a rhizo-box experiment. • Maize demonstrated root avoidance in maize/maize, with reduced root growth in ‘shared’ soil, and increased growth away from its neighbours. Conversely, maize proliferated roots in the proximity of neighbouring faba bean roots that had greater P availability in the rhizosphere (as a result of citrate and acid phosphatase exudation) compared with maize roots. Maize proliferated more roots, but spent less time to reach, and grow out of, the P patches away from neighbours in the maize/maize than in the maize/faba bean experiment. Maize shoot biomass and P uptake were greater in the heterogeneous P treatment with maize/faba bean than with maize/maize system. • The foraging strategy of maize roots is an integrated function of heterogeneous distribution of nutrients and neighbouring plants, thus improving nutrient acquisition and maize growth. Understanding the foraging patterns is critical for optimizing nutrient management in crops.

Introduction and selection of unconventional plants with high concentration of biologically active compounds is one of the worthy ways for producing functional food, which is beneficial to human health. Research was carried out in northern Europe (Russia) with the purpose to assess yield, quality and biologically active compounds concentration in Physalis angulata and Physalis pubescens fruits. P. angulata cultivars Konditer and Konditer 2 gave the highest yield (11.3 and 11.0 t·ha−1 respectively), due to the highest mean fruit weight (80 and 70 g respectively); P. pubescens variety Zolotaya rossip had the worst outcome due to the very small berries (3 g), in spite of their highest number per plant (165). ‘Zolotaya rossip’ fruits overall attained higher values of quality indicators compared to all P. angulata cultivars. Positive correlations were recorded between dry matter and polyphenols as well as between total sugars and polyphenols. Physalis fruits showed to be a good source of antioxidants, K, Mg and P for human beings. Taste index turned out highly reliable in evaluating fruit quality and it was dependant on dry matter, total sugars, polyphenols and Ca.

Plant–soil feedback (PSF) occurs when plants alter soil properties that influence the performance of seedlings, with consequent effects on plant populations and communities. Many processes influence PSF, including changes in nutrient availability and the accumulation of natural enemies, mutualists or secondary chemicals. Typically, these mechanisms are investigated in isolation, yet no single mechanism is likely to be completely responsible for PSF as these processes can interact. Further, the outcome depends on which resources are limiting and the other plants and soil biota in the surrounding environment. As such, understanding the mechanisms of PSF and their role within plant communities requires quantification of the interactions among the processes influencing PSF and the associated abiotic and biotic contexts.

Various human activities – including agriculture, water consumption, river damming, and aquaculture – have intensified over the last century. This has had a major impact on nitrogen (N) and phosphorus (P) cycling in global continental waters. In this study, we use a coupled nutrient-input–hydrology–in-stream nutrient retention model to quantitatively track the changes in the global freshwater N and P cycles over the 20th century. Our results suggest that, during this period, the global nutrient delivery to streams increased from 34 to 64 Tg N yr−1 and from 5 to 9 Tg P yr−1. Furthermore, in-stream retention and removal grew from 14 to 27 Tg N yr−1 and 3 to 5 Tg P yr−1. One of the major causes of increased retention is the growing number of reservoirs, which now account for 24 and 22 % of global N and P retention/removal in freshwater systems, respectively. This increase in nutrient retention could not balance the increase in nutrient delivery to rivers with the consequence that river nutrient transport to the ocean increased from 19 to 37 Tg N yr−1 and from 2 to 4 Tg P yr−1. Human activities have also led to a global increase in the molar N : P ratio in freshwater bodies.