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Aims: In order to understand the role of allelopathy in invasion success, effects of root exudates from Solanum rostratum Dunal on germination and primary growth of wheat and cabbage seeds were studied by vitro bioassay. These results indicated the allelopathy of root exudates and would be helpful for understanding Solanum rostratum Dunal invasion. Study Design: The roots were washed clean for three times with distilled water before they were gathered in a big bucket. The container was filled with distilled water, enough to submerge the roots, and air was aerated constantly with an air pump. The water extract was collected per 24 hs and for four times totally. The water extract from Solanum rostratum was concentrated with a rotary evaporator at 40°C and deposited in a refrigerator at 4°C. All the root exudates were pooled around 1500 mL, and the fresh weight of Solanum rostratum used for exudates collection was 1208 g, the exudate concentration was then marked as 0.8g f w/mL. Place and Duration of Study: Solanum rostratum was grown in the greenhouse on April 15th, 2019, its seeds were collected from the invaded fields in Chaoyang city (Liaoning province, China). Methodology: Petri dish bioassay was applied to test the effects of root exudates of Solanum rostratum on the seeds of wheat and Chinese cabbage. For test of allelochemicals exudated through the root, The compounds in organic fraction of root exudates analysed by GC-MS. Results: These results indicated the allelopathy of root exudates and would be helpful for understanding Solanum rostratum Dunal invasion. Conclusion: Root exudates of Solanum rostratum contained some allelochemicals, which could inhibit the germination and radicle growth of wheat and Chinese cabbage, though the effects of root exudates on shoot growth are different, with a stimulation on Chinese cabbage while a inhibition on wheat. The difference indicated a selectivity of allelopathy effect of root exudates from Solanum rostratum Dunal.

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, butthere is a lack of studies on root exudates of invasive plants in the context of inevitable global warming and nitrogen deposition. In this report, 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. trifidaadaptation 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.

Cold stress, a major environmental factor, has an important impact on the production of landscape plants and crop yield, and its stress and resistance mechanisms have always been hot research issues. Oreorchis patens (Lindl.) Lindl., an important germplasm resource, has strong frost resistance and can resist low temperatures of -40 °C. However, the mechanism by which O. patens responds to cold stress remains poorly understood. Here, we examined the adaptation to the low-temperature environment of O. patens by changing the leaf tissue structure, while the synergistic effect of osmotic regulation, reactive oxygen scavenging and protein improved the resistance to cold stress. In addition, analysis of the photosynthetic system showed that cold stress changes the photosynthetic capacity of O. patens leaves to affect cold resistance. Analysis by nonparametric transcriptome sequencing revealed 2402 genes that were differentially expressed, most of which were related to resistance. Simultaneously, quantitative real-time polymerase chain reaction (qRT-PCR) analysis obtained results consistent with the transcriptome. These results indicated that O. patens could alter leaf structure and physiological and biochemical metabolic processes by initiating resistance-related molecular regulatory networks to improve the ability to resist cold stress. This study was the first to discuss the physiological, biochemical and molecular regulatory mechanisms of O. patens resistance to cold stress, which laid a foundation for revealing the biological and molecular mechanisms of overwintering of O. patens and breeding cold-resistant horticultural crops in northern China.

Environmental heterogeneity is common in nature. Clonal integration is an important trait that allows clonal plants to grow in resource-heterogeneous environments. The aim of this work was to study the effects of clonal integration on the growth and propagation of two root-suckering plant species under water-heterogeneous conditions and to elucidate their adaptive strategy to water stress. Two root-suckering plants of the genus Brassicaceae, Rorippa amphibia and Rorippa sylvestris, have invaded Liaoning Province, China. The greenhouse pot experiments were performed in the research center of the Shenyang Agricultural University. Mother and daughter fragments collected from these two plants were grown under either well-watered or water-limited conditions to mimic the homogeneous and heterogeneous water condition. Morphological traits (root-shoot ratio, the number of new shoots, etc.) and the biomass of mother and daughter fragments were measured. The results showed that clonal integration did not occur under water-homogeneous conditions. However, under water-heterogeneous conditions, clonal integration transported the resources from resource-rich environments to resource-defficient environments. When the resources were re-allocated, clonal integration increased the root-shoot ratio and the number of new shoots on daughter fragments, which facilitated the spread of the plants. At low water availability, R. sylvestris had higher root-shoot ratios and more new shoots on daughter fragments than R. amphibia, suggesting that R. sylvestris had higher invasibility than R. amphibia. The findings enhanced our understanding of how clonal integration facilitates the invasion of root-suckering plants in resource-heterogeneous environments and provided insights into management measures for invasive alien species.