Many plant endophytes produce mycotoxins, but how host genetic variation influences endophyte colonization and mycotoxin production under natural conditions is poorly understood. This interaction has not been fully considered in many previous studies which used controlled experiments with agronomic or model plant species. Here, we investigated this interaction in a naturally occurring forb (a locoweed species) Oxytropis ochrocephala, its symbiotic endophyte Alternaria oxytropis, and the mycotoxin swainsonine. Host genetic variation was characterized by microsatellite markers. Endophyte infection rate and swainsonine levels were determined by PCR and HPLC, respectively. Genetic markers defined two distinct host populations and revealed that host genetics were significantly correlated with geographical location, elevation, and precipitation. As the host diverged, symbiotic interactions were reduced or failed to produce detectable swainsonine in one host population. Host genotype and precipitation had a significant impact in shaping swainsonine production at the population level. This study highlights the effect of host genotype in influencing this interaction in locoweeds.

Buffalograss [Buchloe dactyloides (Nutt.) Engelm.] has become the most widely cultivated warm-season turfgrass in northern China because of its low-maintenance requirements. Nitrogen (N) can be applied to plants in a range of formulations. However, preference of nitrogen uptake and the effects of N form on plant growth and nitrogen accumulation has not been established in buffalograss. In this study, we evaluated the effects of different inorganic nitrogen forms (NO₃⁻-N, NH₄⁺-N, and NO₃⁻-N: NH₄⁺-N = 1:1) on growth and nitrogen accumulation in buffalograss seedlings. Results showed that supply of three N forms significantly increased buffalograss seedlings growth, biomass, and N contents of all plant organs compared with the seedlings receiving free nitrogen. Plants achieved better growth performance when they received nitrate as the sole N source, which stimulated stolon growth and increased the biomass of ramets, spacers, and aboveground and total plant biomass, and also allocated more biomass to ramets and more N to spacers. Meanwhile, those plants supplied with the treatment +NH₄NO₃ displayed a significantly greater N content in the ramet, ¹⁵N abundance, and ¹⁵N accumulation amount in all organs. These data suggest NO₃⁻-N supplied either singly or in mixture increased vegetative propagation and thus facilitates buffalograss establishment. However, applications of ammonium caused detrimental effects on buffalograss seedlings growth, but +NO₃⁻ could alleviate NH₄⁺-induced morphological disorders. Thus, recommendations to increase vegetative propagation and biomass accumulation in buffalograss seedlings should consider increasing NO₃⁻-N in a fertility program and avoiding applications of nitrogen as NH₄⁺-N.

Xanthium spinosum (X. spinosum) is a highly invasive weed native to South America and distributed in 17 provinces (municipalities) of China. It has severely negative influences on ecosystems, agriculture, and husbandry. However, few studies have reported on the impact of human activity and climate change on the future distribution and centroid shift of X. spinosum. This study aimed to investigate the potential geological distribution of X. spinosum in China, as well as the distribution pattern, centroid shift, and key environmental factors influencing its distribution, under four future climate scenarios (SSP1-26, SSP2-45, SSP3-70, and SSP5-85) based on the biomod2-integrated model. The results indicated that the suitable habitats for X. spinosum would expand in the future, mainly in Inner Mongolia, Northeast China, and the plateau regions (e.g., Xinjiang and Xizang). Under future climate scenarios, the centroid would shift toward the northwest or northeast part of China, with the SSP2-45-2050s scenario showing the maximum shift distance (161.990 km). Additionally, the key environmental variables influencing the distribution of X. spinosum, including human impact index, bio5, bio7, and bio12, were determined, revealing that most of them were related to human activities, temperature, and precipitation. This study enhances the understanding of the influence of human activity and climate change on the geographic range of X. spinosum. It provides references for early warning and management in the control of X. spinosum.

The expansion of agriculture and intensive mechanized production have resulted in the loss of habitats and biodiversity, which has led to the loss of ecological services such as the biological control of pests and diseases, and insect-borne pollination. Current studies mainly focus on the impact of small-scale crop diversity (such as intercropping) on ecological service but lack research on the effects of crop diversity at the landscape scale. In this study, vegetation-dwelling arthropods in naked oat (Avena chinensis) fields under different planting patterns were collected at different growth stages by standardized sweep netting sampling, and the differences in arthropod communities and temporal dynamics were analyzed. Taking this information as an example, the effects of crop diversity at the landscape scale caused by different planting patterns on arthropod communities were studied. It was found that herbivores were the most abundant functional group in the arthropod community in naked oat fields, accounting for 70.13% of the total abundance, followed by natural enemies, accounting for 23.45%, and, finally, other insects. The abundance and species richness of natural enemies in naked oat fields under diversified planting pattern were significantly higher than those under intensive planting pattern, while the abundance and species richness of herbivorous pests showed no significant difference between the two planting patterns. Planting patterns significantly affected the composition and structure of arthropod communities in naked oat fields. Significantly higher ratio of natural enemy to pest and more diverse natural enemies under the diversified planting pattern have shown better biological control potential and the significance of biodiversity protection.

Plant leaf stoichiometry reflects its adaptation to the environment. Leaf stoichiometry variations across different environments have been extensively studied in grassland plants, but little is known about intraspecific leaf stoichiometry, especially for widely distributed species, such as Stellera chamaejasme L. We present the first study on the leaf stoichiometry of S. chamaejasme and evaluate its relationships with environmental variables. S. chamaejasme leaf and soil samples from 29 invaded sites in the two plateaus of distinct environments [the Inner Mongolian Plateau (IM) and Qinghai-Tibet Plateau (QT)] in Northern China were collected. Leaf C, N, P, and K and their stoichiometric ratios, and soil physicochemical properties were determined and compared with climate information from each sampling site. The results showed that mean leaf C, N, P, and K concentrations were 498.60, 19.95, 2.15, and 6.57 g kg⁻¹; the average C:N, C:P, N:P, N:K and K:P ratios were 25.20, 245.57, 9.81, 3.13, and 3.21, respectively. The N:P:K-ratios in S. chamaejasme leaf might imply that its growth is restricted by K- or K+N. Moreover, the soil physicochemical properties in the S. chamaejasme-infested areas varied remarkably, and few significant correlations between S. chamaejasme leaf ecological stoichiometry and soil physicochemical properties were observed. These indicate the nutrient concentrations and stoichiometry of S. chamaejasme tend to be insensitive to variations in the soil nutrient availability, resulting in their broad distributions in China’s grasslands. Besides, different homeostasis strength of the C, N, K, and their ratios in S. chamaejasme leaves across all sites were observed, which means S. chamaejasme could be more conservative in their use of nutrients improving their adaptation to diverse conditions. Moreover, the leaf C and N contents of S. chamaejasm were unaffected by any climate factors. However, the correlation between leaf P content and climate factors was significant only in IM, while the leaf K happened to be significant in QT. Besides, MAP or MAT contribution was stronger in the leaf elements than soil by using mixed effects models, which illustrated once more the relatively weak effect of the soil physicochemical properties on the leaf elements. Finally, partial least squares path modeling suggested that leaf P or K contents were affected by different mechanisms in QT and IM regions, suggesting that S. chamaejasme can adapt to changing environments by adjusting its relationships with the climate or soil factors to improve its survival opportunities in degraded grasslands.