Urbanization influences the indoor transfer of airborne antibiotic resistance genes, which has a seasonally dependent pattern.

Over the last few years, the cumulative use of antibiotics in healthcare institutions, as well as the rearing of livestock and poultry, has resulted in the accumulation of antibiotic resistance genes (ARGs). This presents a substantial danger to human health worldwide. The characteristics of airborne ARGs, especially those transferred from outdoors to indoors, remains largely unexplored in neighborhoods, even though a majority of human population spends most of their time there. We investigated airborne ARGs and mobile genetic element (MGE, IntI1), plant communities, and airborne microbiota transferred indoors, as well as respiratory disease (RD) prevalence using a combination of metabarcode sequencing, real-time quantitative PCR and questionnaires in 72 neighborhoods in Shanghai. We hypothesized that (i) urbanization regulates ARGs abundance, (ii) the urbanization effect on ARGs varies seasonally, and (iii) land use types are associated with ARGs abundance. Supporting these hypotheses, during the warm season, the abundance of ARGs in peri-urban areas was higher than in urban areas. The abundance of ARGs was also affected by the surrounding land use and plant communities: an increase in the proportion of gray infrastructure (e.g., residential area) around neighborhoods can lead to an increase in some ARGs (mecA, qnrA, ermB and mexD). Additionally, there were variations observed in the relationship between ARGs and bacterial genera in different seasons. Specifically, Stenotrophomonas and Campylobacter were positively correlated with vanA during warm seasons, whereas Pseudomonas, Bacteroides, Treponema and Stenotrophomonas positively correlated with tetX in the cold season. Interstingly, a noteworthy positive correlation was observed between the abundance of vanA and the occurrence of both rhinitis and rhinoconjunctivitis. Taken together, our study underlines the importance of urbanization and season in controlling the indoor transfer of airborne ARGs. Furthermore, we also highlight the augmentation of green-blue infrastructure in urban environments has the potential to mitigate an excess of ARGs.

Phosphorus elevation erodes ectomycorrhizal community diversity and induces divergence of saprophytic community composition between vegetation types.

Phosphorus (P) is a critical macronutrient that is essential for many life-sustaining processes. Despite decades of work on plant performance under P deficiency and the importance of microbes in ecosystem processes, little is known about how bacterial and fungal flora respond to P gradients and determine the vegetation health. In current study, we examined soil edaphic conditions and microbial communities in 39 untouched natural forests representing phosphorous deficient (Pp) and phosphorus rich (Pr) soils (due to naturally occurring phosphate rocks) in Yunnan Province, China. We also considered the effect of plant functional types by including the dominant tree species. Bacterial and fungal diversity was greater across the Pp sites compared with Pr sites. The relative abundance of Actinobacteria and Gemmatimonadetes was higher across Pp sites, while Chlamydiae and Verrucomicrobia showed the opposite pattern, with greater relative abundance across the Pr sites. Bacterial taxa that were observed in low P soils were more likely having oligotrophic life history strategies. Interestingly, ectomycorrhizal (ECM) fungal diversity was promoted in the Pp sites, indicating that the decreasing soil P concentration and the increasing host P demand foster stimulated the ECM species for hyphal soil exploration. Moreover, the high P level caused saprophytic fungi (SAP) to diverge, causing its enrichment only under Q. variabilis compared to low P soil, where there is no difference in relative abundance of SAP between the two tree species. This likely resulted in an enhanced decomposition process by SAP and elevation of soil properties (Carbon and Nitrogen) under Q. variabilis across the Pr sites. Taken together, our findings highlight the highly diverse microbiome in low P soils. The higher soil P caused shifts of fungal functional guilds, which likely influence tree growth and health (ECM), along with divergence of ecosystem services between tree functional types.

Spatial variations in stomatal traits and their coordination with leaf traits in Quercus variabilis across Eastern Asia.

The stomatal traits influence ecosystem carbon-water fluxes and play essential roles that enable plants to adapt to changing environmental conditions. However, how stomatal traits vary along a large climate gradient and whether stomatal traits coordinated with other leaf functional traits in response to environmental changes remain unclear. We investigated the stomatal density (SD), stomatal size (SS), and leaf traits (leaf area (LA), leaf mass per area (LMA), and vein density (VD)) of 44 in situ Quercus variabilis populations across Eastern Asia (24 to 51.8°N, 99 to 137°E) and 15 populations grown in a common garden, and evaluated their relationships with environmental factors. Stepwise multiple regression showed that the SD was significantly associated with mean annual precipitation (MAP), LMA, and VD, and the SS with latitude, mean annual temperature (MAT), mean monthly solar radiation (MMSR), and VD. The SD was positively correlated with the LMA, while the SS was negatively correlated with the VD. The SD and LMA increased with decreasing precipitation, which indicated that they may coordinate to commonly enhance plant resistance against drought. The SS decreased; however, the VD increased with temperature. This implied that plants might further reduce their SS by increasing VD limitations under global warming. In the common garden, plants exhibited a higher SD and VD and lower SS and LA compared to those in the field; however, no relation between the stomatal and leaf traits was observed. Our results suggested that stomatal traits have high environmental plasticity and are highly coordinated with other leaf functional traits in response to environmental changes. Nevertheless, this coordination may have been formed through long-term adaptations, rather than over short time spans.

Body Size Plasticity of Weevil Larvae (Curculio davidi) (Coleoptera: Curculionidae) and Its Stoichiometric Relationship With Different Hosts.

Parasites obtain energy and nutrients from the host, and their body size is also usually limited by host size. However, the regulatory mechanisms that control the plasticity of parasite body sizes and the stoichiometric relationships with their hosts remain unclear. Here we investigated the concentrations of 14 elements (C, H, O, N, P, S, K, Na, Ca, Mg, Al, Fe, Mn, and Zn) in the acorns of three oak species (Quercus spp.), in their endoparasitic weevil (Curculio davidi Fairmaire) (Coleoptera: Curculionidae) larvae and in the larval feces, and the weight of weevil larvae within different hosts in a warm-temperate zone of China. Our results showed that the three acorn species exhibited significant differences in C, H, O, P, K, Mg, and Mn concentrations. However, in the weevil larvae, only P, Mn, and C:P ratio revealed significant differences. Weevil larvae preferentially absorbed and retained N, Zn, Na, and P, whereas Mn, K, Ca, and O were passively absorbed and transported. The weevil larvae weight was associated with acorn stoichiometry, and positively correlated with acorn size. Weevil larvae P decreased, but Mn and C:P increased with their weight, implying highly variable in somatic stoichiometry are coupled with the plasticity of body size. Interestingly, weevil larvae weight was negatively correlated with acorn infection rate, indicating small-size parasitic insects might have higher fitness level in parasite-host systems than larger-size ones. Our results suggest that variation in P, Mn, and C:P in parasites may play critical roles in shaping their body size and in improving their fitness.

Bacterial Communities Are More Sensitive to Water Addition Than Fungal Communities Due to Higher Soil K and Na in a Degraded Karst Ecosystem of Southwestern China.

Precipitation is predicted to become more intense in Southern China in the context of climate change; however, the responses of microbial communities to variations in soil moisture have not been well documented for karst areas. The climate is typically in a subtropical monsoon category with two different seasons: a dry season (December-May) and a wet season (June-November). Based on a randomized complete block design (RCBD), a water addition experiment (0, +20, +40, and +60% relative to local precipitation) was established in April 2017, with five replicates, in a degraded grass-shrub community. Sampling was performed in May and at the end of August of 2017. Macroelements (C, H, N, P, K, Ca, Mg, and S), microelements (Mn, Fe, Zn, and Cu), and non-essential elements (Na, Al, and Si) were quantified in the soil. The total DNA of the soil samples was analyzed through 16S rRNA amplicon by Illumina Miseq. Subsequent to the addition of water during both the dry and wet seasons, the concentrations of non-metal elements (C, H, N, S, and P, except for Si) in the soil remained relatively stable; however, metal elements (K, Na, Fe, and Mg, along with Si) increased significantly, whereas Zn and Ca decreased. During the dry season, fungal and bacterial communities were significantly distinct from those during the wet season along the PC axis 1 (p < 0.001). Water addition did not alter the compositions of bacterial or fungal communities during the dry season. However, during the wet season, water addition altered the compositions of bacterial rather than fungal community based on principal component analysis. At the phylum level, the relative abundance of Actinobacteria increased with water addition and had a significantly positive correlation with K+ (r 2 = 0.70, p < 0.001) and Na+ (r 2 = 0.36, p < 0.01) contents, whereas that of Acidobacteria, Planctomycetes, and Verrucomicrobia decreased and showed negative correlation with soil K and Na content, and no changes were observed for the fungal phyla. This suggests that the karst bacterial communities can be influenced by the addition of water during the wet season likely linked to changes in soil K and Na contents. These findings implied that increased rainfall might alter the elemental compositions of karst soils, and bacterial communities are likely to be more sensitive to variations in soil moisture in contrast to their fungal counterparts.

Correlated metabolic and elemental variations between the leaves and seeds of oak trees at contrasting geologically derived phosphorus sites.

The leaves and seeds of plants frequently function as the source and sink organs for distinct metabolites, which can interactively vary in response to adverse site conditions. Subtropical soils are typically characterized as having deficient phosphorus (P), calcium (Ca), and magnesium (Mg), with enriched aluminum (Al) and iron (Fe), while Al and manganese (Mn) are toxic at low pH. It remains largely unknown how leaf- and seed-sourced metabolites are synergistically linked to adapt to P-variable soils for trees in subtropical areas. Here we quantified the metabolic and elemental profiling in the mature leaves and immature seeds of Quercus variabilis at contrasting geologically-derived phosphorus sites in subtropical China. The results revealed that carbon (C) and nitrogen (N) based metabolites (primarily sugars and organic acids), as well as enzyme- and protein/nucleic acid-related elements (N, P, Mg, and Mn) played important roles toward characterizing the profiling of metabolites and ionomes in leaves and seeds at two site types, respectively. These metabolites (sugars, amino acids, and fatty acids) and elements (N, P, Mg, and Mn) of seeds were closely related to the sugars, organic acids, and elements (N, P, Mg, and Mn) of leaves at the two site types. For the most part, the content of N and P in the soil affected the accumulation of materials (such as, starchs and proteins) in seeds, as well as N and P assimilation in leaves, by influencing C- and N-containing metabolites in leaves. These results suggested that correlated disparities of C- and N-containing metabolites, along with enzyme- and protein/nucleic acid-related elements in both leaves and seeds played important roles in plants to facilitate their adaptation to nutrient-variable sites in subtropical zones.

Elemental stoichiometry and compositions of weevil larvae and two acorn hosts under natural phosphorus variation.

To understand how different trophic organisms in a parasite food chain adapt to the differences in soil nutrient conditions, we investigated stoichiometric variation and homeostasis of multiple elements in two acorn trees, Quercus variabilis and Quercus acutissima, and their parasite weevil larvae (Curculio davidi Fairmaire) at phosphorus (P)-deficient and P-rich sites in subtropical China where P-rich ores are scattered among dominant P-deficient soils. Results showed that elemental stoichiometry and compositions of both acorns and weevil larvae differed significantly between P-deficient and P-rich sites (p < 0.05), with the largest contribution of acorn and weevil larva P in distinguishing the stoichiometric compositions between the two site types. The two acorn species were statistically separated by their acorn elemental stoichiometry and compositions (p < 0.05), but no difference was observed on weevil larvae between the two acorn species. P was one of the few elements that were non strict homeostasis in both acorns and weevil larvae. These findings highlight the importance of both environmental influence in elemental stoichiometry and composition and physiological regulations of nutritional needs in organisms and provide possible stoichiometric responses of both plants and animals to P loading, a worldwide issue from excess release of P into the environment.

Multielement stoichiometry in Quercus variabilis under natural phosphorus variation in subtropical China.

Plant stoichiometry in relation to environmental factors has recently received increasing attention. However, regulations and variations of plant elements in different environments are not well understood. We investigated homeostasis and variation of macroelements (C, N, P, K, Ca, Mg, and S), essential microelements (Fe, Mn, and Zn) and non-essential elements (Al) in Quercus variabilis leaves at a range of natural P concentration from P-rich to P-deficient (typical subtropical conditions) soils. The results showed that element ratios were more stable (except for C:P and Mn:P) than individual element concentrations. Of the individual elements, protein-related elements (e.g. N, S, and Fe) were correlated with leaf P while non-protein elements (e.g. C, K, and Ca) were not. The degree of homeostasis indicated that macroelements (N, P, and Ca) concentrations were more variable than microelements (Mn, Zn, and Al) under a varying element concentration in soils. These results suggest that local P-rich geochemistry alters leaf element concentrations, but not element ratios, and that plants are capable of meeting their needs for elements in certain proportions to achieve optimal performance under varying elemental conditions.

Climatic control on plant and soil δ(13)C along an altitudinal transect of Lushan mountain in subtropical china: characteristics and interpretation of soil carbon dynamics.

Decreasing temperature and increasing precipitation along altitude gradients are typical mountain climate in subtropical China. In such a climate regime, identifying the patterns of the C stable isotope composition (δ(13)C) in plants and soils and their relations to the context of climate change is essential. In this study, the patterns of δ(13)C variation were investigated for tree leaves, litters, and soils in the natural secondary forests at four altitudes (219, 405, 780, and 1268 m a.s.l.) in Lushan Mountain, central subtropical China. For the dominant trees, both leaf and leaf-litter δ(13)C decreased as altitude increased from low to high altitude, whereas surface soil δ(13)C increased. The lower leaf δ(13)C at high altitudes was associated with the high moisture-related discrimination, while the high soil δ(13)C is attributed to the low temperature-induced decay. At each altitude, soil δ(13)C became enriched with soil depth. Soil δ(13)C increased with soil C concentrations and altitude, but decreased with soil depth. A negative relationship was also found between O-alkyl C and δ(13)C in litter and soil, whereas a positive relationship was observed between aromatic C and δ(13)C. Lower temperature and higher moisture at high altitudes are the predominant control factors of δ(13)C variation in plants and soils. These results help understand C dynamics in the context of global warming.