Hybridization is one of the important factors influencing the adaptive evolution of invasive plants. According to previous studies, hybridization with an invasive plant reduces the adaptability of its native congener to environment. However, in this study, the hybridization with an invasive plant of Xanthium strumarium (LT) improves the tolerance and accumulation of its native congener Xanthium sibiricum (CR) to cadmium (Cd). Under Cd stress, X. sibiricum♀ × X. strumarium♂ (ZCR) showed higher biomass and Cd accumulation. Compared with CR, ZCR has longer vegetative and reproductive growth time. Moreover, ZCR adopted more reasonable biomass allocation strategy. ZCR increased the proportion of reproductive allocation and ensured its own survival with the increase of Cd stress. Furthermore, ZCR increased the translocation of Cd to aboveground parts and changed the distribution of Cd. A large amount of Cd is stored in senescent leaves and eliminated from the plant when the leaves fall off, which not only reduces the Cd content in the plant, but also reduces the toxicity of Cd in the normal leaves. Transcriptome analysis shows a total of 2055 (1060 up and 995 down) differentially expressed genes (DEGs) were detected in the leaves of Cd-stressed ZCR compared with CR, while only 792 (521 up and 271 down) were detected in X. strumarium♀ × X. sibiricum♂ (ZLT) compared with LT. A large number of DGEs in ZCR and ZLT are involved in abscisic acid (ABA) synthesis and signal transduction. The genes induced by ABA in ZCR, including CNGC5/20, CPK1/28, CML, PTI1-like tyrosine-protein kinase 3, respiratory burst oxidase homolog protein C, and WRKY transcription factor 33 were found differentially expressed compared CR. carotenoid cleavage dioxygenase 4, NCED1/2, phytoene synthase 2, and CYP707A involved in ABA synthesis and decomposition in ZLT were found differentially expressed compared LT. We speculated that ABA played an important role in Cd transportation of hybrids and Cd distribution in senescent and normal leaves. The results demonstrate that hybridization with an invasive plant improves the adaptability of the hybrid to Cd stress and may enhance the extinction risk of native congener in pollution environment.

Invasive plants can change the soil ecological environment in the invasion area to adapt to their growth and reproduction through root exudates. Root exudates are the most direct manifestation of plant responses to external environmental changes, but there is a lack of studies on root exudates of invasive plants in the context of inevitable global warming and nitrogen deposition. In this research, we used widely targeted metabolomics to investigate Ambrosia trifida root exudates during seedling and maturity under warming and nitrogen deposition to reveal the possible mechanisms of A. trifida adaptation to climate change. The results showed that the organic acids increased under warming condition but decreased after nitrogen addition in the seedling stage. Phenolic acids increased greatly after nitrogen addition in the mature stage. Most phenolic acids were annotated in the phenylpropane metabolic pathway and tyrosine metabolism. Therefore, nitrogen deposition may increase the adaptability of A. trifida through root exudates, making it more invasive under global warming. The results provide new ideas for preventing and controlling the invasion of A. trifida under climate change.

High nitrogen (N) uptake is one of the main reasons for invasive alien plant invasions. However, little effort has been made to compare the effects of different N forms on N uptake between invasive and native plants, especially those on N form acquisition strategies (preference and plasticity), which influence N uptake, and thus exotic plant invasions. Related studies are particularly few in barren habitats, where the effects of N deposition on invasiveness are considered to be much weaker than in fertile habitats. In this study, we grew Solanum rostratum, a noxious invader in barren habitats, and the native plants Leymus chinensis and Agropyron cristatum in both mono- and mixed cultures under nitrate and ammonium addition treatments, and analyzed the effects of the soil N availability and forms on the growth, N uptake, and N form acquisition strategies for these plants. The invader outperformed the natives in N uptake (in most cases) and growth (always) in both mono- and mixed cultures under all N treatments. N addition increased the N uptake and growth of the invader. The advantages of the invader over the natives were higher under ammonium relative to nitrate addition. The growth advantage of the invader was associated with its higher N uptake and higher N-use efficiency. Higher plasticity in N form uptake may contribute to the higher N uptake for the invader when grown in mixed cultures. Our findings indicate that N deposition, particularly in the form of ammonium, may accelerate exotic plant invasions in barren habitats.

In order to understand the bias and main affecting factors of codon usage in the plastid genome of Diplandrorchis sinica, which is a rare and endangered plant species in the Orchidaceae family, the complete plastid genome sequence of D. sinica was downloaded from the GenBank database and 20 protein-coding sequences that met the analysis requirements were finally selected. The GC content, length of the amino acid (Laa), relative synonymous codon usage (RSCU), and effective number of codon (ENC) of each gene and codon were calculated using the CodonW and EMBOSS online programs. Neutral plot analysis, ENC-plot analysis, PR2-plot analysis, and correspondence analysis were performed using Origin Pro 2024 software, and correlation analysis between various indicators was performed using SPSS 23.0 software. The results showed that the third base of the codon in the plastid genome of D. sinica was rich in A and T, with a GC₃ content of 27%, which was lower than that of GC₁ (45%) and GC₂ (39%). The ENC value ranged from 35 to 57, with an average of 47. The codon usage bias was relatively low, and there was a significant positive correlation between ENC and GC₃. There were a total of 32 codons with RSCU values greater than 1, of which 30 ended with either A or U. There were a total of nine optimal codons identified, namely, UCU, UCC, UCA, GCA, UUG, AUA, CGU, CGA, and GGU. This study indicated that the dominant factor affecting codon usage bias in the plastid genome of D. sinica was natural selection pressure, while the impact of base mutations was limited. The codon usage patterns were not closely related to gene types, and the distribution of photosynthetic system genes and ribosomal protein-coding gene loci was relatively scattered, indicating significant differences in the usage patterns of these gene codons. In addition, the codon usage patterns may not be related to whether the plant is a photosynthetic autotrophic or heterotrophic nutritional type. The results of this study could provide scientific references for the genomic evolution and phylogenetic research of plant species in the family Orchidaceae.

Exploring how nitrogen deposition alters the competitive interactions between invasive plants and native plants is critical for predicting the invasion trends of invasive plants and for formulating their control strategies. In this study, the invasive plant Solanum rostratum and its native congener S. nigrum were selected as research subjects, and three different nitrogen (N) concentration treatments (N1: 50 mg·kg⁻¹, N2: 100 mg·kg⁻¹, N3: 150 mg·kg⁻¹) were set up to compare the two species in terms of growth and development, leaf nutrient utilization strategies, stress tolerance, and rhizosphere microbial community differences under competitive conditions. The results showed that the biomass of S. rostratum was 1.4 to 2.3 times that of S. nigrum; the former had a lower root–shoot ratio and a larger crown width, enabling it to seize more living space and light resources. Across all nitrogen treatments, the net photosynthetic rate of S. rostratum leaves was significantly higher than that of S. nigrum, reflecting a stronger carbon sequestration capacity. With the increase in soil nitrogen concentration, the malondialdehyde content in S. rostratum leaves showed a decreasing trend; meanwhile, its leaf soluble sugar and catalase contents were 3.5 to 4.3 times and 1.5 to 2.5 times those of S. nigrum, respectively, indicating a lower oxidative stress level and higher stress tolerance in S. rostratum. The leaf C/P and C/N ratios of S. rostratum increased with the rise in soil N, demonstrating a higher nutrient use efficiency, while the decrease in leaf phosphorus (P) content might be attributed to the element dilution effect caused by the rapid plant growth. In addition, the diversity and stability of the rhizosphere microbial community of S. rostratum gradually increased with increasing soil N and were significantly higher than those of S. nigrum. The rhizosphere-recruited microbes of the genera Comamonas and Chryseobacterium may help promote its root nutrient absorption and thus enhance its competitive ability. Collectively, our findings reveal that under exogenous N application, S. rostratum gains a significant growth advantage over S. nigrum, which is attributed to its stronger capacities for carbon assimilation and spatial resource acquisition, a nutrient strategy characterized by low acquisition and high utilization, as well as a stable and diverse rhizosphere microbial community.