Effect of salt-alkali stress on seed germination of the halophyte Halostachys caspica.

The increasing global phenomenon of soil salinization has prompted heightened interest in the physiological ecology of plant salt and alkali tolerance. Halostachys caspica belonging to Amaranthaceae, an exceptionally salt-tolerant halophyte, is widely distributed in the arid and saline-alkali regions of Xinjiang, in Northwest China. Soil salinization and alkalinization frequently co-occur in nature, but very few studies focus on the interactive effects of various salt and alkali stress on plants. In this study, the impacts on the H. caspica seed germination, germination recovery and seedling growth were investigated under the salt and alkali stress. The results showed that the seed germination percentage was not significantly reduced at low salinity at pH 5.30-9.60, but decreased with elevated salt concentration and pH. Immediately after, salt was removed, ungerminated seeds under high salt concentration treatment exhibited a higher recovery germination percentage, indicating seed germination of H. caspica was inhibited under the condition of high salt-alkali stress. Stepwise regression analysis indicated that, at the same salt concentrations, alkaline salts exerted a more severe inhibition on seed germination, compared to neutral salts. The detrimental effects of salinity or high pH alone were less serious than their combination. Salt concentration, pH value, and their interactions had inhibitory effects on seed germination, with salinity being the decisive factor, while pH played a secondary role in salt-alkali mixed stress.

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Harm from alien invasive plants is increasing in Jingzhou County, Hunan Province. Based on a one-year field investigation and available literature, we investigated species composition, origin, flora, degree of harm and distribution pattern of invasive plants in the county. The results showed that there were 34 invasive plant species from 27 genera and 16 families in this County. The dominant invasive species belonged to Asteraceae (8 species) and Amaranthaceae (6 species), which accounted for 23.5% and 17.7%, respectively. The majority of invasive plants originated from South America (45.7%) and North America (30.4%). Tropical flora showed a significantly higher representation than temperate flora, signifying robust tropical characteristics amongst the invasive plant population. Based on hazard level classification, we recognized four types as malicious invasion (Level 1): Alternanthera philoxeroides, Erigeron annuus, E. canadensis, and Xanthium chinense. In addition, five types were classified as severe invasion (Level 2), eight types as local invasion (Level 3), fifteen types as general invasion (Level 4), while two types were still under observation (Level 5). The pattern of distribution demonstrated that invasive plants in Jingzhou County mostly spread along the verges of transportation roads, in human settlements, and in a few areas of water flow. The higher levels of invasion damage were principally concentrated in the central part of Jingzhou County.

Effects of periodic heat events on the reproduction and longevity of female and male Agasicles hygrophila (Coleoptera: Chrysomelidae).

Alternanthera philoxeroides (Amaranthaceae), commonly known as alligator weed, is a globally invasive and detrimental perennial weed. Agasicles hygrophila serves as an important biocontrol agent for alligator weeds. However, during mid-summer, when temperatures increase, A. hygrophila populations experience a significant decline, leading to ineffective weed control. This study has examined the impact of periodic heat events on the reproduction and survival of A. hygrophila females and males using various mating combinations and durations of temperature treatments. The results demonstrated significant effects on all of the studied parameters across mating combinations when compared with the control. Under the same temperature combination, the fecundity and survival rates of females, as well as the egg-hatching rate, decreased significantly with increasing repeated heat exposure. Furthermore, the egg-hatching rate varied significantly among different temperatures and time-interval combinations. In addition, the females displayed greater sensitivity to heat stress than males in terms of fecundity. These findings enhance our understanding of A. hygrophila population dynamics during summer and provide insights into the release of biocontrol agents in diverse regions with varying climates.

Insights into Regulation of C2 and C4 Photosynthesis in Amaranthaceae/Chenopodiaceae Using RNA-Seq.

Amaranthaceae (incl. Chenopodiaceae) shows an immense diversity of C4 syndromes. More than 15 independent origins of C4 photosynthesis, and the largest number of C4 species in eudicots signify the importance of this angiosperm lineage in C4 evolution. Here, we conduct RNA-Seq followed by comparative transcriptome analysis of three species from Camphorosmeae representing related clades with different photosynthetic types: Threlkeldia diffusa (C3), Sedobassia sedoides (C2), and Bassia prostrata (C4). Results show that B. prostrata belongs to the NADP-ME type and core genes encoding for C4 cycle are significantly upregulated when compared with Sed. sedoides and T. diffusa. Sedobassia sedoides and B. prostrata share a number of upregulated C4-related genes; however, two C4 transporters (DIT and TPT) are found significantly upregulated only in Sed. sedoides. Combined analysis of transcription factors (TFs) of the closely related lineages (Camphorosmeae and Salsoleae) revealed that no C3-specific TFs are higher in C2 species compared with C4 species; instead, the C2 species show their own set of upregulated TFs. Taken together, our study indicates that the hypothesis of the C2 photosynthesis as a proxy towards C4 photosynthesis is questionable in Sed. sedoides and more in favour of an independent evolutionary stable state.

Physiological responses of Agriophyllum squarrosum and Setaria viridis to drought and re-watering.

Drought resistance of psammophyte determines survival and growth, but their responses to drought are not well understood. We conducted a pot experiment to study how physiological characteristics respond to drought and rehydration. We found that watering to 60-65% of field capacity (the control) provided more water than was required by Agriophyllum squarrosum and its leaves became yellow and slightly wilted. The total chlorophyll content and Fm (maximum fluorescence after dark adaptation) in control were lower than in the drought treatment, and both decreased after rehydration. With increasing drought duration and intensity, the relative water content (RWC), chlorophyll content, Fm, and the quantum efficiency of photosystem II (Fv/Fm) of Setaria viridis decreased, but malondialdehyde and membrane permeability increased. During the late drought, the activities of three antioxidant enzymes in A. squarrosum increased to prevent membrane lipid peroxidation; for S. viridis, only peroxidase and superoxide dismutase activities increased. After rehydration, RWC of both species increased, but Fv/Fm of A. squarrosum and Fm of S. viridis did not recover under severe drought. Our research illustrated that A. squarrosum is better adapted to arid environment than S. viridis, but the high soil moisture content is not conducive to normal growth of A. squarrosum.

The effects of water control on the survival and growth of Alternanthera philoxeroides in the vegetative reproduction and seedling stages.

Alternanthera philoxeroides (Martius) is an infamous invasive alien plant that is widely distributed in aquatic and terrestrial habitats. To investigate the vegetative reproduction, growth, survival strategy, and the function of leaves in fragment of A. philoxeroides under different water conditions, two water control experiments were conducted with different leaf treatments: (1) water control with stolon fragments, and (2) water control with plants. The water control was subjected to five levels: I 30% soil water content, II 70% soil water content, III 97% soil water content, IV water depth of 5 cm, and V water depth of 10 cm in combination with the two leaf treatments, fragments with two leaves and fragments without leaves. Based on the results, A. philoxeroides produced a significantly higher stem length, node number, leaf number, stem biomass, leaf biomass, and total biomass in the 97% soil water content and in treatments with leaves. Additionally, the stem mass ratio increased and the root mass ratio decreased with the increase of the water content. In Exp. 1, the survival rate was the highest in the 97% water content and was 0 in the 30% water content. Therefore, the leaves of stolon fragments contribute to the vegetative reproduction and growth of A. philoxeroides. In response to different water conditions, A. philoxeroides adopts different strategies according to the resource reserves by itself, which are conducive to its survival and widespread occurrence.

Identify potential allelochemicals from Humulus scandens (Lour.) Merr. root extracts that induce allelopathy on Alternanthera philoxeroides (Mart.) Griseb.

Although it is well-documented that invasion of invasive plants is promoted with allelopathic effects by inhibiting the growth and phenotypic performance of native plants, little is known conversely. In this study, the allelopathy effects of a native plant, Humulus scandens (Lour.) Merr., on a typical invasive species Alternanthera philoxeroides (Mart.) Griseb., was investigated by exposing A. philoxeroides seedlings to three chemical solvent extracts (i.e., petroleum ether extract (PE), ethyl acetate extract (EE), and n-butanol extract (NE) of H. scandens root (HR). The three chemical extracts inhibited the growth, stem length, node number, leaf number, leaf area, and root number, and increased malondialdehyde (MDA) content of A. philoxeroides seedlings, which indicated that the extracts inhibited the plant growth by damaging the membrane system of leaves. And the synthetical effect of allelopathy (SE) index indicated that EE had the greatest inhibition on the growth of A. philoxeroides. Fifty compounds were identified from the three extracts of HR using GC-MS analysis, among which 5 compounds (dibutyl phthalate, stigmasta-3,5-diene, 2,6-Di-tert-butylphenol campesterol, and neophytadiene) were identified from H. scandens root extracts for the first time. And n-hexadecanoic acid exists in all three extracts. The findings of the present study provide a novel method to potentially control the invasion of A. philoxeroides. However, field monitoring under natural conditions would be necessary to confirm in practice the results obtained with the bioassays.

Biological control agent attack timing and population variability, but not density, best explain target weed density across an environmental gradient.

Spatial variation in plant-herbivore interactions can be important in pest systems, particularly when insect herbivores are used as biological control agents to manage invasive plants. The geographic ranges of the invasive plant alligatorweed (Alternanthera philoxeroides) and its biological control agent the alligatorweed flea beetle (Agasicles hygrophila) do not completely overlap in the southeastern USA, producing spatial heterogeneity in interaction strength that may be related to latitude-correlated environmental gradients. We studied this system near the range margin of the alligatorweed flea beetle to test whether spatial variation in alligatorweed density was best explained by agent mean or maximum density, variability in agent density, agent attack timing, or a combination of biological control and environmental (i.e., weather) variables. The pattern that emerged was that mean agent and host densities were negatively and positively associated with latitude, respectively. Variability in agent density increased with latitude and was positively correlated with host density. We further discovered that agent first attack timing was negatively correlated with winter and spring temperatures and spring and summer precipitation, and positively correlated with seasonal temperature extremes, which was then directly influential on agent density and variability in density, and indirectly on host density. This study demonstrates that, contrary to common wisdom, weather-related timing of agent activity and population variability, but not agent mean density, contribute to the spatial heterogeneity observed in alligatorweed populations.

Blue and red light affects morphogenesis and 20-hydroxyecdisone content of in vitro Pfaffia glomerata accessions.

The combination of different colors from light-emitting diodes (LEDs) may influence growth and production of secondary metabolites in plants. In the present study, the effect of light quality on morphophysiology and content of 20-hydroxyecdysone (20E), a phytoecdysteroid, was evaluated in accessions of an endangered medicinal species, Pfaffia glomerata, grown in vitro. Two accessions (Ac22 and Ac43) were cultured in vitro under three different ratios of red (R) and blue (B) LEDs: (i) 1R:1B, (ii) 1R:3B, and (iii) 3R:1B. An equal ratio of red and blue light (1R:1B) increased biomass accumulation, anthocyanin content, and 20E production (by 30-40%). Moreover, 1R:1B treatment increased the size of vascular bundles and vessel elements, as well as strengthened xylem lignification and thickening of the cell wall of shoots. The 1R:3B treatment induced the highest photosynthetic and electron transport rates and enhanced the activity of oxidative stress-related enzymes. Total Chl content, Chl/Car ratio, and NPQ varied more by accession type than by light source. Spectral quality affected primary metabolism differently in each accession. Specifically, in Ac22 plants, fructose content was higher under 1R:1B and 1R:3B treatments, whereas starch accumulation was higher under 1R:3B, and sucrose under 3R:1B. In Ac43 plants, sugars were not influenced by light spectral quality, but starch content was higher under 3R:1B conditions. In conclusion, red and blue LEDs enhance biomass and 20E production in P. glomerata grown in vitro.

Antibacterial and Potential Antidiabetic Activities of Flavone C-glycosides Isolated from Beta vulgaris Subspecies cicla L. var. Flavescens (Amaranthaceae) Cultivated in Egypt.

BACKGROUND: Diabetes mellitus is the most common disease in Egypt. In this context, Beta vulgaris subspecies cicla L. var. flavescens is an edible plant that has been used in traditional medicine as a therapy for treating some diseases. OBJECTIVES: The current study was performed to evaluate the antibacterial and potential anti-diabetic activities of different extracts and isolated flavone C-glycoside compounds isolated from Beta vulgaris subspecies cicla L. var. flavescens leaves. METHODS: Phytochemical investigation of n-butanol extract led to the isolation of five phytoconstituents. Their structures were determined by spectroscopic tools, including 1D-NMR (1H- & 13C-NMR) and 2D-NMR (HMQC & HMBC) besides the comparison of the data with the literature. The extracts and phytoconstituents were evaluated in vitro for their activity against some bacterial pathogens, which represent prominent human pathogens, particularly in hospital settings. The antibacterial activity was examined against three Gram-positive bacterial strains (Staphylococcus aureus, Staphylococcus epidermidis & Enterococcus faecalis) and five Gram-negative ones (Pseudomonas aeruginosa, Proteus vulgaris, Klebsiella pneumoniae, Proteus mirabilis & Salmonella typhimurium) relative to Ciprofloxacin as a reference drug. Furthermore, the in vitro antidiabetic activity (Type II) was evaluated using the alpha-glucosidase inhibitory assay. RESULTS: Five flavone C-glycosides namely; Apigenin 8-C-ß-D-glucopyranoside (vitexin) (1), 2''-Oxylopyranosylvitexin (2), acacetin 8-C-ß-D-glucopyranoside (3), acacetin 8-C-α-L-rhamnoside (4), and 6,8-di-C-ß-D-glucopyranosylapigenin (vecinin-II) (5) were isolated from n-butanol extract of B. vulgaris subspecies cicla L. var. flavescens. Compound 1 showed a promising antibacterial activity against most of the test bacterial strains with respect to the minimum inhibitory concentration values (MIC) ranged from 1.95 to 15.63 µg ml-1. On the other hand, compounds 1 and 3 demonstrated superior antidiabetic activities with IC50 values of 35.7 and 42.64 µg ml-1, respectively, while an inferior potential antidiabetic activity was recorded for compound 4 (IC50 = 145.5 µg ml-1) in comparison with Acarbose as a reference drug. CONCLUSION: B. vulgaris L. is an edible plant, which could be used as a natural source of antibiotic and hypoglycemic drugs.

Future N deposition and precipitation changes will be beneficial for the growth of Haloxylon ammodendron in Gurbantunggut Desert, northwest China.

Evaluation of precipitation and nitrogen (N) deposition in desert ecosystems helps to elucidate the reaction of desert ecosystems to future environmental changes. An in-situ field experiment was established to examine the influence of a long-term enhanced precipitation and N deposition on the photosynthetic traits and physiological characteristics of Haloxylon ammodendron in the Gurbantunggut Desert, northwest China, throughout the growing season in 2014-2016. Results showed a significant interaction between precipitation and N applications. Increased precipitation and N deposition and their coupling could significantly improve photosynthetic capacity, alter the variability in amplitude of water potential and change the content of substances regulating osmotic pressure in H. ammodendron. According to the comprehensive evaluation of H. ammodendron's adaptability using six different water and N coupling models, a combination of a 30% increase in precipitation and a 30 kg N ha-1 yr-1 addition in nitrogen deposition, or the addition of N at a concentration of 60 kg N ha-1 yr-1 with natural precipitation were beneficial to H. ammodendron growth and development. Hence, changes in the future global environment can be anticipated to be beneficial to H. ammodendron growth.

Selenium enhanced phytoremediation of diesel contaminated soil by Alternanthera philoxeroides.

Using a 60-day pot culture experiment, we investigated the effect of selenium on phytoremediation of soil containing high-level diesel by Alternanthera philoxeroides (alligator weed). Diesel (20 g kg-1) decreased the growth of A. philoxeroides and induced oxidative stress, as indicated by tissue levels of hydrogen peroxide (H2O2) and malondialdehyde (MDA). Adding Se (0.5 or 1.5 mg kg-1) to diesel-treated soil alleviated oxidative stress and improved biomass production, and the low dose was as effective as the high dose. After 60 days, the reduction in rhizospheric soil diesel was 20.1 ±â€¯0.55% without Se and 35.2 ±â€¯3.6% with Se, showing a significant increase in efficiency. Again, the low Se dose was as effective as the high dose. These findings advance the field phytoremediation by demonstrating that Se, at 0.5 mg kg-1, enhances removal and increases plant tolerance to petroleum hydrocarbons.

A multi-species comparison of selective placement patterns of ramets in invasive alien and native clonal plants to light, soil nutrient and water heterogeneity.

A worth noticing pattern in current invasive biology is the clonal ability of many of the world's worst invasive plants. Selective placement of ramets (i.e. foraging behavior) can intensify ramet performance and allocation, and place more ramets in the more favorable microhabitats, which can maximum utilize resource and share risk in heterogeneous environments. Still little is known about whether invasive alien and native clonal plants differ in the selective placement patterns of ramets in invasive clonal plants or not. We used five congeneric pairs of naturally co-occurring invasive alien and native clonal plant species in China. In a glasshouse, we grew all species in pots under a homogeneous and three heterogeneous conditions (i.e. light, soil nutrients or water) subjected to resource-high or -low patches. All biomass parameters and number of ramets significantly increased in resource-high patches in all three types of heterogeneous environments. Interestingly, growth of invasive alien plants benefited significantly more from resource-high patches than native plants in all heterogeneous environments. Overall, invasive had higher biomass parameters per ramet than natives. Ramet parameters of invasive plants also benefited more from resource-low patches than natives. Three different selective placement patterns of ramets in resource-low patches were exhibited in invasive plants: ramet increasing shoot investment (above pattern), increasing root investment (below pattern) and increasing both investments (complete pattern) in the light, soil water and nutrient heterogeneity, respectively. Investment on less, larger ramet was the adaptive strategy of invasive plants in resource-poor patches. The results suggest that adaptively selective placement patterns of ramets promote a higher morphology plasticity and performance in invasive clonal plants over natives. When alien clonal plants spread new areas with light, soil nutrients or water heterogeneity, selective placement patterns of ramets might play an important role in plant performance and competitive superior by capitalizing more on additional resources.

Cloning and Functional Analysis of SaCLCc1, a Gene Belonging to the Chloride Channel Family (CLC), from the Halophyte Suaeda altissima (L.) Pall.

One of the genes of the CLC (Chloride Channel) family, SaCLCc1, from the halophyte Suaeda altissima (L.) Pall. was cloned. To investigate the function of SaCLCc1, it was expressed in the S. cerevisiae deletion mutant Δgef1::LEU2 for the only gene of the CLC family in this organism. The growth of the transformed SaCLCc1-expressing mutant Δgef1 was restored when cells were grown in Fe2+-deficient YPEG medium, in minimal synthetic media SD and SR (pH 7.0), and in rich YPD medium containing Mn2+. The complementation of the Δgef1 mutant phenotype with the SaClCc1 gene indicates the involvement of the SaClCc1 protein in the transport of Cl- ions.

Cadmium associates with oxalate in calcium oxalate crystals and competes with calcium for translocation to stems in the cadmium bioindicator Gomphrena claussenii.

Cadmium (Cd) was shown to co-localise with calcium (Ca) in oxalate crystals in the stems and leaves of Cd tolerant Gomphrena claussenii, but Cd binding remained unresolved. Using synchrotron radiation X-ray absorption near edge spectroscopy we demonstrate that in oxalate crystals of hydroponically grown G. claussenii the vast majority of Cd is bound to oxygen ligands in oxalate crystals (>88%; Cd-O-C coordination) and the remaining Cd is bound to sulphur ligands (Cd-S-C coordination). Cadmium binding to oxalate does not depend on the amount of Ca supplied or from which organs the crystals originate (stems and mature leaves). By contrast, roots contain no oxalate crystals and therein Cd is bound predominantly by S ligands. The potential to remove Cd by extraction of Cd-rich oxalate crystals from plant material should be tested in phytoextraction or phytomining strategies.

Analysis of physiological traits in the response of Chenopodiaceae, Amaranthaceae, and Brassicaceae plants to salinity stress.

Soil salinity is one of the main factors affecting plant growth. Dissection of plant response to salinity into physiological traits may result a simple approximation than the overall response that may influence many aspects of the plant. In the present study two factors were considered to evaluate the correlation of different physiological variables in the plant response to salinity. The first factor was the species, with four levels (Atriplex halimus, Salicornia fruticosa, Cakile maritima, and Brassica rapa), and the second was the salinity (0, 100, 200, and 300 mM NaCl). Thus, the interrelationships of distinct physiological traits - leaf succulence, minerals (micronutrients and macronutrients), plant water relations (osmotic potential, water potential, and hydraulic conductivity), protein content, catalase, and unsaturated fatty acids - were analyzed by Discriminant Canonical Analysis (DCA). Additional information supplied by the interaction between the variables provided a multivariate response pattern in which the two factors (species x salinity) influenced the relationship between responses rather than affecting a single response. Such analysis allows to establish whether the selected trait was associated to each other for helping to define the best set of parameters in relation to the response of new genotypes to salinity. Thus, plant growth was influenced by leaf succulence adaptation to salt stress whereas it was not determined by water relations. The Na ion prevailed over K as the element with the highest variability in the response to salinity in A. halimus and S. fruticosa, whereas in C. maritima and B. rapa, Ca, S, and P stood out more. Patterns of ion accumulation together with the protein and unsaturated fatty acid ratios could be used in discriminating plant response to salt stress may be positioned in interrelated groups. The results highlight new evidences in the response to salt stress associated to a specific interrelationship of a set of physiological parameters.

Actinomycetes: an unexplored microorganisms for plant growth promotion and biocontrol in vegetable crops.

Actinomycetes, a Gram positive bacteria, well reported as a source of antibiotics, also possess potential to control various plant pathogens, besides acting as plant growth promoting agent. Chemicals in different forms are extensively being used in vegetable farming, adversely affecting the environment and consumer health. Microbial agent like actinomycetes can substantially replace these harmful chemicals, and have now started finding a place as an important input in to farming practices. Only selected vegetable crops belonging to 11 different families have been explored with use of actinomycetes as biocontrol and plant growth promoting agent till now. It provides ample opportunities to vegetable researchers, to further explore with use of this very important group of microorganisms, in order to achieve even higher production level of safe vegetables. Mycostop and Actinovate are two actinomycetes based formulations globally available for use in vegetable farming as a substitute for chemical formulations. Present review article has summarized the literature available on use of actinomycetes in vegetable farming. Existing wide gap in knowledge, and potential thrust areas for future research have also been projected.

Latitudinal variation in soil biota: testing the biotic interaction hypothesis with an invasive plant and a native congener.

Soil biota community structure can change with latitude, but the effects of changes on native plants, invasive plants, and their herbivores remain unclear. Here, we examined latitudinal variation in the soil biota community associated with the invasive plant Alternanthera philoxeroides and its native congener A. sessilis, and the effects of soil biota community variation on these plants and the beetle Agasicles hygrophila. We characterized the soil bacterial and fungal communities and root-knot nematodes of plant rhizospheres collected from 22 °N to 36.6 °N in China. Soil biota community structure changed with latitude as a function of climate and soil properties. Root-knot nematode abundance and potential soil fungal pathogen diversity (classified with FUNGuild) decreased with latitude, apparently due to higher soil pH and lower temperatures. A greenhouse experiment and lab bioassay showed native plant mass, seed production, and mass of beetles fed native foliage increased with soil collection latitude. However, there were no latitudinal patterns for the invasive plant. These results suggest that invasive and native plants and, consequently, their herbivores have different responses to latitudinal changes in soil-borne enemies, potentially creating spatial variation in enemy release or biotic resistance. This highlights the importance of linking above- and below-ground multitrophic interactions to explore the role of soil biota in non-native plant invasions with a biogeographic approach.

Responses in shoot elongation, carbohydrate utilization and growth recovery of an invasive species to submergence at different water temperatures.

Widely distributed amphibious exotic plant species may respond plastically to water temperatures when submerged. Alternanthera philoxeroides, a highly flood-tolerant species, originates from tropical regions and has successfully invaded temperate regions. The wide distribution of this species suggests it can respond to flooding at different water temperatures. In this study, the plastic responses of A. philoxeroides plants to submergence at water temperatures of 10 °C, 20 °C and 30 °C were investigated. The A. philoxeroides plants had large pools of non-structural carbohydrates, which were readily mobilized upon submergence. Submergence hindered biomass accumulation and decreased the carbohydrate content level and respiration rate (P < 0.05). Water temperature had remarkable effects on shoot elongation, carbohydrate utilization and recovery growth. With decreasing water temperature, the respiration rate was lower and carbohydrate content decreased more slowly, but the post-submergence biomass accumulation was faster (P < 0.05), indicating a beneficial effect of low water temperature for recovery. However, high water temperatures accelerated shoot elongation (P < 0.05), which benefitted the submerged plants more if contact with air was restored. These results suggest that the species can respond to different water temperatures plastically, which may provide hints for its invasion success in regions with diverse climates.

The mutual restraint effect between the expansion of Alternanthera philoxeroides (Mart.) Griseb and cadmium mobility in aquatic environment.

Alternanthera philoxeroides (Mart.) Griseb is one of the most malignant weeds in its invision habitats. While in the cadmium-contaminated aquatic environment, does A. philoxeroides possess good tolerance and adaptability? To demonstrate the effects of cadmium on A. philoxeroides in the polluted water bodies, a hydroponic stress experiment was conducted over a gradient of Cd concentrations (0, 2.5 and 5mg/l) in triplicate. The seedlings were cultured in a greenhouse and harvested on days 0, 10, 20, 30 and 40, respectively. The results showed the effects of mutual restraint between Cd and A. philoxeroides. The A. philoxeroides seedlings were enriched with large amounts of Cd, and the toxicity of Cd inhibited the rapid growth of A. philoxeroides and induced the rapid degradation of chlorophylls in its tissues. Furthermore, the use of iron plaque effectively immobilized Cd of 1123-2883mg/kg·DW on the root surface, thus it decreased the transferability of Cd in the aquatic environment. Due to its extensive adaptability, good Cd tolerance and the immobilization of Cd predominantly in the roots (the highest Cd concentration enriched was 7588.65±628.90mg/kg·DW in roots). A. philoxeroides effectively restrained the translocation of Cd and partitioned Cd in the roots within water bodies. CAPSULE: The antagonistic effect exists between the invasion of A. philoxeroides and cadmium mobility in aquatic environments.