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Photodynamic therapy (PDT) uses a combination of photosensitizers with visible light to generate reactive species and selectively kill tumor or unwanted tissue. Znln2S4 nanoparticles are widely implemented in photovoltaic device materials and photolysis water catalysts owing to their unique photoelectric properties. Whether Znln2S4 itself can be used as an effective dye in PDT is still unknown. To determine the effects and potential mechanism of Znln2S4PDT on HepG2 cell apoptosis, electron microscopic analysis was performed to monitor the apoptotic morphology of HepG2 cells upon exposure to Znln2S4-PDT. Flow cytometry was performed to measure the apoptosis rate and intracellular ROS production. Western blot and ELISA were performed to reveal the expression changes in Bax, caspase-3 and caspase-9. Data from this work suggested that cells exhibited the typical apoptotic morphology in response to Znln2S4-PDT, with high apoptotic rate. The intracellular ROS production after Znln2S4-PDT occurred in a dose-dependent manner. Moreover, Znln2S4-PDT augmented the expression levels of pro-apoptosis factors, especially, Bax, caspase-3 and caspase-9. Taken together, our novel findings, Znln2S4-PDT elicited HepG2 cell apoptosis, suggesting Znln2S4 as a promising photosensitizer candidate for cancer therapy.

Aims Intercropping cereals with legumes may achieve high crop yields at reduced input levels. Several studies have indicated that intercropping increases phosphorus use efficiency but no overarching analysis exists on the role of species traits and input levels. Here we synthesize the available information on P use efficiency in cereal/legume intercropping. Methods Global data on yields, P uptake and nutrient input in cereal/legume mixtures were extracted from the literature and statistically analyzed. Co-variables explaining P uptake efficiency and yield were considered. Results P uptake was substantially increased with an average value of LER P , the land equivalent ratio for P uptake, of 1.24, and an average NE P (observed P uptake minus expected P uptake) of 3.67 kg P ha −1 . The conversion efficiency of P uptake to biomass decreased with P uptake and was lower in intercrops than in sole crops but the conversion efficiency to yield was not affected by intercropping. The P fertilizer requirement was 21% lower in intercrops than in sole crops for the same yields. Conclusions Substantial improvements in land use efficiency and P uptake are obtained by cereal/legume intercropping. Cereal/legume intercropping has therefore potential to increase P fertilizer use efficiency in agriculture.

Salinization of soil with sodium chloride ions inhibits plant functions, causing reduction of yield of crops. Salt tolerant microorganisms have been studied to enhance crop growth under salinity. This review describes the performance of endophytic fungi applied to crops as a supplement to plant genetics or soil management to alleviate salt stress in crops. This is achieved via inducing systemic resistance, increasing the levels of beneficial metabolites, activating antioxidant systems to scavenge ROS, and modulating plant growth phytohormones. Colonization by endophytic fungi improves nutrient uptake and maintains ionic homeostasis by modulating ion accumulation, thereby restricting the transport of Na+ to leaves and ensuring a low cytosolic Na+:K+ ratio in plants. Participating endophytic fungi enhance transcripts of genes encoding the high Affinity Potassium Transporter 1 (HKT1) and the inward-rectifying K+ channels KAT1 and KAT2, which play key roles in regulating Na+ and K+ homeostasis. Endophytic-induced interplay of strigolactones play regulatory roles in salt tolerance by interacting with phytohormones. Future research requires further attention on the biochemical, molecular and genetic mechanisms crucial for salt stress resistance requires further attention for future research. Furthermore, to design strategies for sustained plant health with endophytic fungi, a new wave of exploration of plant-endophyte responses to combinations of stresses is mandatory.

Aims Alpine ecosystems are important terrestrial carbon (C) pools, and microbial decomposers play a key role in cycling soil C. Microbial metabolic limitations in these ecosystems, however, have rarely been studied. The objectives of this study are to reveal the characteristics of microbial nutrient limitation, and decipher the drivers in the alpine ecosystems. Methods Models of extracellular enzymatic stoichiometry were applied to examine and compare the metabolic limitations of the microbial communities in bulk and rhizosphere soils along an altitudinal gradient (2800–3500 m a.s.l.) under the same type of vegetation ( Abies fabri ) on Gongga Mountain, eastern Tibetan Plateau. Results The soil microbial communities suffered from relative C and phosphorus (P) limitations in the alpine ecosystem despite of high soil nutrient contents here. Partial least squares path modelling (PLS-PM) revealed that the limitations were directly regulated by soil nutrient stoichiometry, followed by nutrient availability. The C and P limitations were higher at the high altitudes (3000–3500 m) than that at the low altitude (2800 m), which mainly attribute to changes of soil temperature and moisture along the altitudinal gradient. This suggested that global warming may relieve microbial metabolic limitation in the alpine ecosystems, and then is conducive to the retention of organic C in soil. Furthermore, the C and P limitations varied significantly between the bulk and rhizosphere soils at the high altitudes (3200–3500 m), but not at the low altitudes. This indicated the influences of vegetation on the microbial metabolisms, while the influences could decrease under the scenario of global warming. Conclusions Our study suggests that the alpine ecosystems with high organic C storage harbour abundant microbial populations limited by relative C and P, which have sensitive metabolic characteristics. This could thus potentially lead to large fluctuations in the soil C turnover under climate change. The study provides important insights linking microbial metabolisms to the environmental gradients, and improves our understanding of C cycling in alpine ecosystems.

Background and aims As drought threatens the yield and quality of maize ( Zea mays L.), it is important to dissect the molecular basis of maize drought tolerance. Flavonoids, participate in the scavenging of oxygen free radicals and alleviate stress-induced oxidative damages. This study aims to dissect the function of flavonoids in the improvement of maize drought tolerance. Methods Using far-infrared imaging screening, we previously isolated a drought overly insensitivity ( doi ) mutant from an ethyl methanesulfonate (EMS)-mutagenized maize library and designated it as doi57 . In this study, we performed a physiological characterization and transcriptome profiling of doi57 in comparison to corresponding wild-type B73 under drought stress. Results Under drought stress, doi57 seedlings displayed lower leaf-surface temperature (LST), faster water loss, and better performance in growth than B73. Transcriptome analysis reveals that key genes involved in flavonoid biosynthesis are enriched among differentially expressed genes in doi57 . In line with these results, more flavonols and less hydrogen peroxide (H 2 O 2 ) were accumulated in guard cells of doi57 than in those of B73 with the decrease of soil water content (SWC). Moreover, the capacity determined from doi57 seedling extracts to scavenge oxygen free radicals was more effective than that of B73 under the drought treatment. Additionally, doi57 seedlings had higher photosynthetic rates, stomatal conductance, transpiration rates, and water use efficiency than B73 exposed to drought stress, resulting in high biomass and greater root/shoot ratios in doi57 mutant plants. Conclusion Flavonoids may facilitate maize seedling drought tolerance by lowering drought-induced oxidative damage as well regulating stomatal movement.

Aims To investigate the effects of polystyrene microplastics (PS-beads) on the soil properties, photosynthesis of Flowering Chinese cabbage, the rhizosphere microbial community and their potential correlation in soil with different residues. Methods The influences of PS-beads (PS-MPs, M1, 5 μm; PS-NPs, M2, 70 nm) on the plant photosynthesis and growth parameters, soil dissolved organic matter (DOM) and the characteristic functional groups, the microbial community and metabolism prediction were studied by a pot-experiment in soil without residues (N), with biochar (B), degradable mulching film (DMF) fragments (D), or biochar and DMF (BD). Key results Chlorophyll a was more susceptible to the exogenous substances than Chlorophyll b. In soil with different residues, PS-beads of different sizes could change different components, structures and functional groups in aromatic rings of DOM, might further change the microbial community and metabolism. M2 decreased TDN and NO 3 − and increased the weight of the plant in group D. M2 increased the weight of the plant in group N. M2 decreased the net photosynthetic rate in group B. The different sizes of PS-beads affected the different parameters of plant growth and potentially changed the plant growth and photosynthetic parameters through altering the microbial metabolism and the correlation among microbes. The potential mechanisms of PS-beads changing the plant growth were different in soil with different residues. Conclusions Our results evidenced the PS-beads potentially changed the plant growth and photosynthesis by changing the microbial metabolism and the correlation among microbes.

Background and aims While the coupled effects of root exudates and microbial feedbacks on soil processes are well-recognized, we still lack an understanding of differences in root exudate fluxes and the associated ecological consequences among tree growth forms. Methods Two deciduous tree species (i.e., Cercidiphyllum japonicum and Larix kaempferi ) and two evergreen tree species (i.e., Pinus armandi and Pinus tabulaeformis ) were selected to perform an in-situ collection of root exudates during the growing season in 2016. The net N mineralization rates and associated microbial enzyme activities were measured in rhizosphere and bulk soils to evaluate rhizosphere effects. Moreover, we compiled the dataset related to root exudation and their associated biological traits and the soil chemical properties for 21 tree species from temperate forests. Results The root exudation rates and the annual root exudate carbon (C) fluxes of two deciduous tree species were significantly higher than those of the two evergreen tree species. Correspondingly, the rhizosphere effects of deciduous tree species on the microbial biomass, enzyme activity and net N mineralization rate were approximately 1.9, 1.6 and 2.4 times greater than those of the evergreen tree species, respectively. Rhizosphere effects were positively correlated with the root exudation rate. The compiled dataset also suggest that deciduous tree species tend to have higher exudation rates than evergreen tree species in temperate forests. Conclusions Collectively, these results suggest that the two tree growth forms exhibit different patterns in root exudate inputs and associated rhizosphere microbial processes. Generally, deciduous tree species tend to exude more C into the soil and consequently induce greater microbial feedback on soil N transformations during the growing season in temperate regions, implying that deciduous tree species induced a greater effect on the C and nutrient cycling in rhizosphere soil than evergreen tree species.

Aim We estimated how seasonality in conjunction with key climatic variables affects morphological and physiological plant functional traits (PFTs) and soil essential (micro and macro) nutrients in oak, pine, and mixed forests. Method The different PFTs were tested using several laboratory methods and using the portable photosynthesis system Li-COR 6400 XT, Lincoln NE, USA. Likewise, some chemical traits and soil nutrients were analyzed by using CHNS analyzer. Results In this study, physiological traits such as CO 2 assimilation rate, stomatal conductance and transpiration rate were significantly higher in the rainy season followed by summer and winter seasons. Among the different forest land uses, physiological traits and resource use efficiency have been significantly higher in oak forest (OF) compared to the mixed forest (MF) and pine forest (PF). Likewise, the concentration of macro–micro nutrients was also recorded higher during the rainy season. The concentration of macro–micro nutrients was higher in OF than in MF and PF in different forest land uses. Conclusion Changes in PFTs ultimately affect the ecosystem services imparted by the different forests. Such changes lead to the local adaptation of these forests through the interaction between PFTs and soil nutrients.

Aims In the production of the natural medicinal plant American ginseng, replantation typically fails due to continuous cropping obstacles. However, the cause is still not clear and needs more research. Methods Soil samples were collected from (a) maize fields where American ginseng had never been planted, (b) fields where American ginseng had just been harvested, and (c) fields where maize had been planted for 2, 4 and 6 years respectively after American ginseng. We investigated the physicochemical properties, the enzymatic activities, and the soil microbial community structure and composition of the samples. Results We found that the content of soil salt, NH 4 + -N, and NO 3 − -N increased significantly in samples associated with the production of American ginseng, whereas the soil pH, carbon-to-nitrogen ratio, alkaline phosphatase, and cellulase activity all significantly decreased and gradually recovered to the pre-planting level. Moreover, the bacterial diversity decreased, while fungal diversity and richness increased; fungal richness continued to increase in farmlands replanted maize. The relative abundance of some microbial communities was changed significantly and was gradually restored with a longer time to replant maize. Pearson’s correlation analysis shown that significantly changed microbial communities were significantly associated with changes in soil pH, soil salt and nitrogen content, alkaline phosphatase, and cellulase activity. Conclusions Changes in soil pH, soil salt and nitrogen content caused changes in microbial community structure and composition, as well as cellulase and alkaline phosphatase activity. These changes may cause the continuous cropping obstacles of American ginseng and may be improved by planting maize.

Aims Increasing soil organic carbon (SOC) stocks is discussed as negative emission technology with the potential to remove relevant amounts of carbon from the atmosphere. At the same time, climate change-driven losses of SOC to the atmosphere might impede such goals. Methods In this study, we used an ensemble of different SOC models and climate projections to project SOC stocks in German croplands up to 2099 under different climate change scenarios. We then estimated the required increase in organic carbon (OC) input to preserve or increase SOC stocks. Results Projected SOC stocks of German croplands are estimated to decline under current OC input levels and management, both with and without climate change. Depending on the climate scenario, we estimated that the OC input to the soil in 2099 needs to be between 51% (+ 1.3 Mg ha − 1 ) and 93% (+ 2.3 Mg ha − 1 ) higher than today to preserve current SOC stock levels. A SOC stock increase of 34.4% (4‰ a − 1 ) would even require an OC input increase of between 221% (+ 5.5 Mg ha − 1 ) and 283% (+ 7.1 Mg ha − 1 ). Conclusions Our study highlights that under climate change increasing SOC stocks is considerable challenging since projected SOC losses have to be compensated first before SOC built up is possible. This would require unrealistically high OC input increases with drastic changes in agricultural management.