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The subjects of this study were two congeneric species of the genus Bidens , the European native Bidens tripartita and the invasive Bidens frondosa . The aim of this research was to determine: (1) the selenium content of the specimens of these species and the soils in which they grew, (2) the role of habitat parameters in shaping selenium levels in the soil and the plants studied, and (3) the bioaccumulation potential of the plants studied, taking habitat conditions into account. Specimens of both species were collected from riverbanks in Poland and Montenegro, and the Se concentrations in each specimen and in the soil sample from each site were measured. Our studies indicate that the invasive species B. frondosa has significantly higher selenium concentrations and greater bioaccumulation abilities (BCF > 1) compared to B. tripartita. Despite the average selenium concentration in the soil being higher in Poland than in Montenegro, Se concentration accumulated in B. frondosa collected in Montenegro was higher, it was also observed that soil chemical properties affect Se bioaccumulation in this species. The type of land use within each site has also been identified according to CORINE classification. The results of the study indicated a great significance of human impact on the selenium enrichment of plants, as the specimen collected in artificial rivers and areas impacted by anthropogenic pression contained much higher amounts of Se than plants growing in more natural habitats. The results also illustrated that the invasive species that have the ability to accumulate selenium, like B. frondosa , can be an exogenous root of this particular trace element for living organizms.

Chloroplast genomes for 3 Bidens plants endemic to China ( Bidens bipinnata Linn., Bidens pilosa Linn., and Bidens alba var. radiata ) have been sequenced, assembled and annotated in this study to distinguish their molecular characterization and phylogenetic relationships. The chloroplast genomes are in typical quadripartite structure with two inverted repeat regions separating a large single copy region and a small single copy region, and ranged from 151,599 to 154,478 bp in length. Similar number of SSRs and long repeats were found in Bidens , wherein mononucleotide repeats (A/T), forward and palindromic repeats were the most in abundance. Gene loss of clpP and psbD , IR expansion and contraction were detected in these Bidens plants. It seems that ndhE , ndhF , ndhG , and rpl32 from the Bidens plants were under positive selection while the majority of chloroplast genes were under purifying selection. Phylogenetic analysis revealed that 3 Bidens plants clustered together and further formed molophyletic clade with other Bidens species, indicating Bidens plants might be under radiation adaptive selection to the changing environment world-widely. Moreover, mutation hotspot analysis and in silico PCR analysis indicated that inter-genic regions of ndhD-ccsA , ndhI-ndhG, ndhF-rpl32, trnL_UAG-rpl32, ndhE-psaC, mat K -rps16, rps2-atpI, cemA-petA , petN-psbM were candidate markers of molecular identification for Bidens plants. This study may provide useful information for genetic diversity analysis and molecular identification for Bidens species.

Biodegradable chelating agents and nitrogen (N) fertilizers are widely used for the remediation of heavy metal-contaminated soils due to their ability to promote plant growth, enhance metal mobility and facilitate plant uptake. In this study, a pot experiment was conducted to investigate the effects of nitrate nitrogen (N-NO 3 − ), ammonium nitrogen (N-NH 4 + ) and amide nitrogen (N-amide) with different concentrations of 25, 50 and 75 mg N·kg −1 combined with ( S , S )-ethylenediaminedisuccinic acid (EDDS) (1 mmol·L −1 ) on growth, biomass and phytoextraction efficiency of Bidens. pilosa L. and the bioavailability of cadmiun (Cd) in 15 mg·kg −1 Cd-contaminated soil. The results demonstrated that the application of 50 mg N·kg −1 N-NO 3 − and EDDS not only promoted plant growth and increased biomass, it also changed Cd distribution between operational fractions, increased available Cd content in soil, thereby maximizing the Cd uptake, thus enhancing the Cd enrichment capability of B. pilosa L. This combination achieved the maximum phytoextraction efficiency of 12.12% and the maximum soil Cd removal of 12.38% across all treatments. The comprehensive score obtained using the membership function method also showed that the treatment with 50 mg N·kg −1 N-NO 3 − and EDDS had the highest score. In conclusion, combination of 50 mg N·kg −1 N-NO 3 − and EDDS resulted in the greatest biomass production, and highest phytoremediation efficiency, indicating that it has great potential for application in phytoremediation with B. pilosa L. in Cd-contaminated soil.

It is now widely recognized that Bidens pilosa has become a problematic broadleaf weed in many ecosystems across the world and, particularly in the light of recent climate change conditions, closer management strategies are required to curtail its impact on agricultural cropping. In this investigation, experiments were conducted to evaluate the effect of environmental factors on the germination and emergence of B. pilosa , and also on the response of this weed to commonly available post-emergence herbicides in Australia. The environmental factors of particular interest to this current work were the effect of light and temperature, salinity, burial depth and moisture on B. pilosa since these are key management issues in Australian agriculture. In addition, the effects of a number of commonly used herbicides were examined, because of concerns regarding emerging herbicide resistance. In the tested light/dark regimes, germination was found to be higher at fluctuating day/night temperatures of 25/15 °C and 30/20 °C (92–93%) than at 35/25 °C (79%), whilst across the different temperature ranges, germination was higher in the light/dark regime (79–93%) than in complete darkness (22–38%). The standard five-minute temperature pretreatment required for 50% inhibition of maximum germination was found to be 160 °C, and it was further shown that no seeds germinated at temperatures higher than 240 °C. With regard to salinity, some B. pilosa seeds germinated (3%) in 200 mM sodium chloride (NaCl) but all failed to germinate at 250 mM NaCl. Germination declined from 89% to 2% as the external osmotic potential decreased from 0 to −0.6 MPa, and germination ceased at −0.8 MPa. Seeding emergence of B. pilosa was maximum (71%) for seeds placed on the soil surface and it was found that no seedlings emerged from a depth of 8 cm or greater. A depth of 3.75 cm was required to inhibit the seeds to 50% of the maximum emergence. In this study, application of glufosinate, glyphosate and paraquat provided commercially acceptable control levels (generally accepted as >90%) when applied at the four-leaf stage of B. pilosa . However, none of the herbicide treatments involved in this study provided this level of control when applied at the six-leaf stage. In summary, B. pilosa germination has been clearly shown to be stimulated by light and thus its emergence was greatest from the soil surface. This suggests that infestation from this weed will remain as a problem in no-till conservation agriculture systems, the use of which is increasing now throughout the world. It is intended that information generated from this study be used to develop more effective integrated management programs for B. pilosa and similar weeds in commercial agricultural environments which are tending toward conservation approaches.

To study the effects of intercropping with accumulator plants on heavy metal accumulation of fruit trees, plants of three Bidens species ( Bidens pilosa , Bidens biternata , and Bidens parviflora ) were intercropped with Ziziphus acidojujuba seedlings under cadmium (Cd)-contaminated conditions (5 mg kg −1 ). Intercropping with Bidens species increased the biomass and chlorophyll b content of Z. acidojujuba seedlings compared with monoculture, but decreased their carotenoid content. Intercropping with Bidens species also improved the activity of superoxide dismutase, peroxidase, and catalase in Z. acidojujuba seedlings compared with monoculture. Intercropping with Bidens species decreased the Cd content in the roots of Z. acidojujuba seedlings compared with monoculture. Conversely, when intercropped with B. pilosa , B. biternata , and B. parviflora , the Cd content in the shoots of Z. acidojujuba seedlings increased by 62.18%, 60.10%, and 62.18%, respectively, compared with that of those monocultured. When intercropped with Z. acidojujuba seedlings, the Cd accumulation amount of three Bidens species plants were ranked B. parviflora > B. biternata > B. pilosa . Therefore, intercropping with plants of three Bidens species is not suitable for Cd-contaminated jujube orchards.

Phytoremediation with the use of hyperaccumulating plant species to remove excess trace metals from contaminated soil and water is considered a cost-effective non-invasive technique. Over 400 plant taxa worldwide have been identified as natural hyperaccumulators, but only very few are reported to hyperaccumulate Cd. Bidens pilosa L. is a newly found, promising Cd hyperaccumulator, although its potential to accumulate Cd and mechanism of this process are not yet well known. This paper was aimed at exploring hyperaccumulation capacity of B . pilosa for Cd, and its translocation behavior related to cell membrane permeability. The highest Cd concentration in shoots of B . pilosa grown in soil was 405.91 mg kg −1 and of that cultured in nutrient solution 1651.68 mg kg −1 , indicating very high accumulation potential. Cd concentrations in the root, stem, leaf, and shoot of B . pilosa cultured in nutrient solution were all much higher than those in soil, while biomass development was considerably lower. This resulted in lesser differences between Cd maximum accumulation loads in the shoot (462 and 365 μg pot −1 ) and in the root (100 and 96 μg pot −1 ) of B . pilosa grown in solution and in soil, respectively. Relative electric conductivity (REC), K + relative permeability ratio, and MDA (malondialdehyde) contents, which are major indices expressing cell membrane permeability, appeared to be closely related to Cd translocation and accumulation. The relative molecular mechanism of Cd accumulation/translocation in B . pilosa was found of importance and needs to be elucidated.

Alstonia scholaris is a tropical evergreen tree native to South and Southeast Asia. Alstonia forests frequently lack understory species. However, potential mechanisms—particularly the allelochemicals involved—remain unclear. In the present study, we identified allelochemicals of A. scholaris, and clarified the role of allelopathic substances from A. scholaris in interactions with neighboring plants. We showed that the leaves, litter, and soil from A. scholaris inhibited growth of Bidens pilosa—a weed found growing abundantly near A. scholaris forests. The allelochemicals were identified as pentacyclic triterpenoids, including betulinic acid, oleanolic acid, and ursolic acid by using ¹H and ¹³C-NMR spectroscopy. The half-maximal inhibitory concentration (IC₅₀) for radicle growth of B. pilosa and Lactuca sativa ranged from 78.8 μM to 735.2 μM, and ursolic acid inhibited seed germination of B. pilosa. The triterpenoid concentrations in the leaves, litter, and soil were quantified with liquid chromatography-electrospray ionization/tandem mass spectrometry. Ursolic acid was present in forest soil at a concentration of 3,095 μg/g, i.e., exceeding the IC₅₀. In the field, ursolic acid accumulated abundantly in the soil in A. scholaris forests, and suppressed weed growth during summer and winter. Our results indicate that A. scholaris pentacyclic triterpenoids influence the growth of neighboring weeds by inhibiting seed germination, radicle growth, and functioning of photosystem II.

Invasive alien species drive extensive ecological changes and cause unexpected risks worldwide. Perceptive germination requirements and the growth function of invasive species are crucial for understanding their invasion and subsequent dissemination in various environmental conditions. Therefore, the germination response of invasive Conyza bonariensis , Parthenium hysterophorus , and Bidens pilosa of Asteraceae family were examined under alternating temperature regimes and some environmental factors. The prevailing germination ability occurs highest at moderate-temperature regimes at 20/30°C attained by 94.83% ( C . bonariensis ) and at 20/25 SS by 96.28% ( P . hysterophorus ) and high-temperature regimes at 25/30°C reached 92.94% ( B . pilosa ) respectively. The half germination percentage (G 50 ) was -0.406 MPa and 2878.35 ppm ( B . pilosa ), -0.579 MPa and 2490.9 ppm ( C . bonariensis ), and — 0.32 MPa and 2490.8 ppm ( P . hysterophorus ) affected by osmotic pressure and salt stress (NaCl) respectively. The highest growth plasticity characteristics were identified in total dry mass attained at 0.968 ( C . bonariensis ), 0.985 ( B . pilosa ) and 0.957 ( P . hysterophorus ) respectively. The relative growth, net assimilation and plasticity index appeared higher in both B . pilosa , and C. bonariensis than P . hysterophorus in the invaded area. In conclusion, germination and growth traits are precisely functional factors that correlate to invasion success under stressed conditions, and zones, and also lead to successful control plans for invasive species and ecological protection.

Invasive species pose significant threats to ecosystems by reducing biodiversity, introducing new diseases, and competing with native species for resources. Bidens pilosa L., a globally invasive weed originating in tropical America, severely impacts agricultural productivity by infesting 31 economically vital crops across over 40 countries. This study examined the global distribution of Bidens pilosa L., under current and future climate scenarios. Using species distribution models and occurrence data, we identified key factors influencing its spread, including temperature, precipitation, and human influence. Our findings suggest a likely decline of suitable habitats in tropical regions and an expansion into temperate regions, with climate suitability decreasing under higher temperatures. Additionally, historical reconstructions emphasize that the rapid spread of the species was facilitated by maritime trade routes. Management strategies are proposed that emphasize the need for enhanced control measures in high-risk areas and conservation efforts in its native range in tropical America. Overall, this research contributes to understanding the dynamics of B. pilosa distribution and informs proactive management strategies to mitigate its ecological and economic impacts.