Search Results (10)

Notorious invasive Bohemian knotweed Reynoutria × bohemica Chrtek et Chrtková is a hybrid of two species, Reynoutria japonica Houtt. and Reynoutria sachalinensis (F. S. Petrop.) Nakai in T. Mori which spontaneously developed in Europe, outside the natural distribution of its parental species. Its success could potentially lie in its allelopathic activity, which was confirmed in a number of experiments conducted with the leaf and root exudates, testing their effect on the germination and growth of various test plants. Here, we tested its allelopathic potential using different concentrations of leaf exudates on two test plants, Triticum aestivum L. and Sinapis alba L., in Petri dishes and pots with soil and by growing test plants in the soil sampled in knotweed stands on the edges of stands and outside of stands. Tests in Petri dishes and pots with soil to which leaf exudates were added have shown a decrease in germination and growth in comparison to the control, hence confirming the allelopathic effect. However, this was not confirmed in a test with in situ soil samples, where no statistically significant differences were observed, neither in the growth of test plants nor in the chemical characteristics (pH, soil organic matter, humus content) of the soil. Therefore, the persistence of Bohemian knotweed at already invaded sites could be attributed to its efficient use of resources (light and nutrients) through which it outcompetes native plants. Full article

Improving ecological connectivity (EC) within landscapes by establishing corridors and ecological networks has been proposed to counteract the negative effects of habitat fragmentation and climate change on biodiversity. To be functional, ecological networks should be kept free of opportunistic invasive species that can disrupt EC between protected areas and cause biodiversity loss. The present study focused on perennial herbaceous species whose occurrence in the Adriatic-Ionian region has increased in the last two decades, namely common milkweed (Asclepias syriaca), Jerusalem artichoke (Helianthus tuberosus), Japanese knotweed (Reynoutria japonica), Bohemian knotweed (Reynoutria × bohemica), giant hogweed (Heracleum mantegazzianum), giant goldenrod (Solidago gigantea), Canadian goldenrod (Solidago canadensis), and Bermuda buttercup (Oxalis pes-caprae). All species have a high potential to spread in grasslands, abandoned agricultural fields, forest edges, and riparian areas and pose a significant threat to native plant communities and biodiversity. Restoring heavily infested sites is a major challenge because these perennial invaders are very persistent and tend to alter the soil environment in invaded habitats and prevent the recolonization of native plant communities. Therefore, early action should be taken to prevent the spread of these environmental weeds in ecological networks and protected areas with high conservation value. Full article

Perennial herbaceous Fallopia is native to East Asia, and was introduced to Europe and North America in the 19th century as an ornamental plant. Fallopia has been spreading quickly and has naturalized in many countries. It is listed in the world’s 100 worst alien species. Fallopia often forms dense monospecies stands through the interruption of the regeneration process of indigenous plant species. Allelopathy of Japanese knotweed (Fallopia japonica), giant knotweed (Fallopia sachalinensis), and Bohemian knotweed (Fallopia x bohemica) has been reported to play an essential role in its invasion. The exudate from their roots and/or rhizomes, and their plant residues inhibited the germination and growth of some other plant species. These knotweeds, which are non-mycorrhizal plants, also suppressed the abundance and species richness of arbuscular mycorrhizal fungi (AMF) in the rhizosphere soil. Such suppression was critical for most territorial plants to form the mutualism with AMF, which enhances the nutrient and water uptake, and the tolerance against pathogens and stress conditions. Several allelochemicals such as flavanols, stilbenes, and quinones were identified in the extracts, residues, and rhizosphere soil of the knotweeds. The accumulated evidence suggests that some of those allelochemicals in knotweeds may be released into the rhizosphere soil through the decomposition process of their plant parts, and the exudation from their rhizomes and roots. Those allelochemicals may inhibit the germination and growth of native plants, and suppress the mycorrhizal colonization of native plants, which provides the knotweeds with a competitive advantage, and interrupts the regeneration processes of native plants. Therefore, allelopathy of knotweeds may contribute to establishing their new habitats in the introduced ranges as invasive plant species. It is the first review article focusing on the allelopathy of knotweeds. Full article

Hyperglycemia, when sustained over a long time in diabetes mellitus (DM), leads to biochemical and cellular abnormalities, primarily through the formation of advanced glycation end-products (AGEs). In the treatment of diabetes, beside blood-sugar-lowering medications, a consumption of herbal products that can inhibit the AGEs’ formation is recommended. This study investigated the in vitro antiglycoxidative potential of extracts and fractions from the rhizomes of Japanese, Giant, and Bohemian knotweeds (Reynoutria japonica (Houtt.), R. sachalinensis (F. Schmidt) Nakai, and R.× bohemica Chrtek et Chrtkova). Their effects on glycooxidation of bovine and human serum albumin were evaluated by incubation of the proteins with a mixture of glucose and fructose (0.5 M) and 150 µg/mL of extract for 28 days at 37 °C, followed by measuring early and late glycation products, albumin oxidation (carbonyl and free thiol groups), and amyloid-β aggregation (thioflavin T and Congo red assays). The highest antiglycoxidative activity, comparable or stronger than the reference drug (aminoguanidine), was observed for ethyl acetate and diethyl ether fractions, enriched in polyphenols (stilbenes, phenylpropanoid disaccharide esters, and free and oligomeric flavan-3-ols). In conclusion, the antiglycoxidative compounds from these three species should be further studied for potential use in the prevention and complementary treatment of DM. Full article

The Asian knotweed species complex gathers some of the world’s most successful plant invaders including the Japanese knotweed (Reynoutria japonica), the giant knotweed (R. sachalinensis) and the hybrid of these two species, the Bohemian knotweed (R. × bohemica). Hybrid species often present higher competitive abilities compared to their parent species. While several studies have focused on the effects of knotweed invasion on plant communities, few have simultaneously considered (i) effects of the three taxa on native plant communities and (ii) effects on litter and soil faunal components. In this study, we compared the differential effects of three Asian knotweeds on vegetation and soil macroinvertebrates communities across seven sites on a regional scale in North Western France. All three knotweed species displayed similar negative effects on local plant species richness, while promoting the taxonomic richness of litter-dwelling macroinvertebrates. Belowground macroinvertebrate taxonomic richness appeared strongly reduced by the presence of the hybrid R. × bohemica, significantly more so than those of sites colonized by R. japonica or R. sachalinensis. These changes of belowground communities were correlated to associated changes of composition and richness within plant communities. This study provides new insight into the consequences of ecosystem invasion by these species, especially revealing the even further strength of impacts of the hybrid Bohemian knotweed on local vegetation and belowground macroinvertebrates than those of other Asian knotweeds, which points to the need for monitoring the spatial spread of R. × bohemica and describing further its effects on ecosystem properties. Full article

Flavan-3-ols and proanthocyanidins of invasive alien plants Japanese knotweed (Fallopia japonica Houtt.), giant knotweed (Fallopia sachalinensis F. Schmidt) and Bohemian knotweed (Fallopia × bohemica (Chrtek & Chrtkova) J.P. Bailey) were investigated using high performance thin-layer chromatography (HPTLC) coupled to densitometry, image analysis and mass spectrometry (HPTLC–MS/MS). (+)-Catechin, (−)-epicatechin, (−)-epicatechin gallate and procyanidin B2 were found in rhizomes of these three species, and for the first time in Bohemian knotweed. (−)-Epicatechin gallate, procyanidin B1, procyanidin B2 and procyanidin C1 were found in giant knotweed rhizomes for the first time. Rhizomes of Bohemian and giant knotweed have the same chemical profiles of proanthocyanidins with respect to the degree of polymerization and with respect to gallates. Japanese and Bohemian knotweed have equal chromatographic fingerprint profiles with the additional peak not present in giant knotweed. Within the individual species giant knotweed rhizomes and leaves have the most similar fingerprints, while the fingerprints of Japanese and Bohemian knotweed rhizomes have additional peaks not found in leaves. Rhizomes of all three species proved to be a rich source of proanthocyanidins, with the highest content in Japanese and the lowest in Bohemian knotweed (based on the total peak areas). The contents of monomers in Japanese, Bohemian and giant knotweed rhizomes were 2.99 kg/t of dry mass (DM), 1.52 kg/t DM, 2.36 kg/t DM, respectively, while the contents of dimers were 2.81 kg/t DM, 1.09 kg/t DM, 2.17 kg/t DM, respectively. All B-type proanthocyanidins from monomers to decamers (monomers—flavan-3-ols, dimers, trimers, tetramers, pentamers, hexamers, heptamers, octamers, nonamers and decamers) and some of their gallates (monomer gallates, dimer gallates, dimer digallates, trimer gallates, tetramer gallates, pentamer gallates and hexamer gallates) were identified in rhizomes of Bohemian knotweed and giant knotweed. Pentamer gallates, hexamers, hexamer gallates, nonamers and decamers were identified for the first time in this study in Bohemian and giant knotweed rhizomes. Full article

In a laboratory experiment, we studied the insecticidal effects of invasive alien plants on the rice weevil. The research was carried out in two parts. In the first part, we studied the insecticidal properties of seven different plant species, namely, Bohemian knotweed (Fallopia × bohemica), Japanese knotweed (Fallopia japonica), false indigo-bush (Amorpha fruticosa), tree of heaven (Ailanthus altissima), staghorn sumac (Rhus typhina), Canada goldenrod (Solidago canadensis), and giant goldenrod (Solidago gigantea). Mixtures of powders and wheat were prepared in two different concentrations, namely, 2.5 w% and 1.25 w%. The experiment was performed at temperatures 20 °C and 25 °C and at two humidity levels, 55% R.h. and 75% R.h. Very low mortality (below 8%) was found when using combinations with the higher relative humidity. No significant differences were observed between the effects of these concentrations. In the second part of the experiment, Norway spruce wood ash and diatomaceous earth (product SilicoSec®) were added to the powder obtained by milling leaves of four different invasive plant species (Canada goldenrod, staghorn sumac, tree of heaven, false indigo). In the independent application, wheat was added to the powder at a concentration 2.5 w%. In the treatments that involved mixtures of powder and wood ash/diatomaceous earth, we applied 1.25 w% plant powder and 1.25 w% wood ash or 1.25 w% plant powder and 450 ppm of a SilicoSec® preparation. The positive control was carried out as two separate treatments with 2.5 w% wood ash of Norway spruce and 900 ppm of the SilicoSec^® product, while untreated wheat represented the negative control. The experiment was performed at two temperatures (20 °C and 25 °C) and two R.h. values (55 and 75% R.h.). The mortality of beetles was recorded on the 7th, 14th, and 21st day after the start of the experiment. Higher mortality rates of rice weevil adults were found at the higher relative humidity, and an important factor of mortality was also the day of exposure, as a higher mortality was found when the exposure of individuals to the tested substances was for a longer time period. After 21 days at 25 °C and 55% R.h., the combinations in which the lower concentration of Norway spruce wood ash was added to the powder of invasive alien plants achieved more than 90% mortality of beetles. By adding the plant powder of invasive alien plants to wood ash, we achieved a greater insecticidal efficacy of invasive plants and lower concentrations of wood ash. Nevertheless, the results of our research do not indicate any great usefulness of the plant powder of invasive plants in suppressing the rice weevil. Additional studies should primarily focus on the insecticidal efficacy of powder from the genus Solidago, which in our study, displayed the greatest insecticidal potential among the tested invasive plants. Full article

Knotweed is a flowering plant that is native to temperate and subtropical regions in the northern hemisphere. We evaluated Japanese (Reynoutria japonica Houtt.) and Bohemian (Fallopia x bohemica) knotweed rhizome and flower ethanol extracts and compared them in terms of their biological activities. The specific polyphenols were identified and quantified using HPLC/DAD, and the antioxidant activity was determined using 2,2-diphenly-1-picrylhydrazyl (DPPH) and cellular antioxidant capacity assays. The anticancer activity was evaluated as the difference between the cytotoxicity to cancer cells compared with control cells. The antimicrobial activity was determined using bacteria and yeast. The antidiabetic activity was tested as the ability of the extracts to inhibit α-amylase. Both rhizome extracts were sources of polyphenols, particularly polydatin and (−)-epicatechin; however, the cellular assay showed the highest antioxidant capacity in the flower extract of F. bohemica. The PaTu cell line was the least sensitive toward all knotweed extracts. The flower extracts of both species were less toxic than the rhizomes. However, the activity of the tested extracts was not specific for cancer cells, indicating a rather toxic mode of action. Furthermore, all used extracts decreased the α-amylase activity, and the rhizome extracts were more effective than the flower extracts. None of the extracts inhibited bacterial growth; however, they inhibited yeast growth. The results confirmed that rhizomes of Reynoutria japonica Houtt. could become a new source of bioactive compounds, which could be used for the co-treatment of diabetes and as antifungal agents. Full article

This is the first report on identification of all B-type proanthocyanidins from monomers to decamers (monomers—flavan-3-ols, dimers, trimers, tetramers, pentamers, hexamers, heptamers, octamers, nonamers, and decamers) and some of their gallates in leaves of Japanese knotweed (Fallopia japonica Houtt.), giant knotweed (Fallopia sachalinensis F. Schmidt) and Bohemian knotweed (Fallopia × bohemica (Chrtek & Chrtkova) J.P. Bailey). Flavan-3-ols and proanthocyanidins were investigated using high performance thin-layer chromatography (HPTLC) coupled to densitometry, image analysis, and mass spectrometry (HPTLC–MS/MS). All species contained (−)-epicatechin and procyanidin B2, while (+)-catechin was only detected in Bohemian and giant knotweed. (−)-Epicatechin gallate, procyanidin B1 and procyanidin C1 was only confirmed in giant knotweed. Leaves of all three knotweeds have the same chemical profiles of proanthocyanidins with respect to the degree of polymerization but differ with respect to gallates. Therefore, chromatographic fingerprint profiles of proanthocyanidins enabled differentiation among leaves of studied knotweeds, and between Japanese knotweed leaves and rhizomes. Leaves of all three species proved to be a rich source of proanthocyanidins (based on the total peak areas), with the highest content in giant and the lowest in Japanese knotweed. The contents of monomers in Japanese, Bohemian and giant knotweed were 0.84 kg/t of dry weight (DW), 1.39 kg/t DW, 2.36 kg/t, respectively, while the contents of dimers were 0.99 kg/t DW, 1.40 kg/t, 2.06 kg/t, respectively. Giant knotweed leaves showed the highest variety of gallates (dimer gallates, dimer digallates, trimer gallates, tetramer gallates, pentamer gallates, and hexamer gallates), while only monomer gallates and dimer gallates were confirmed in Japanese knotweed and monomer gallates, dimer gallates, and dimer digallates were detected in leaves of Bohemian knotweed. The profile of the Bohemian knotweed clearly showed the traits inherited from Japanese and giant knotweed from which it originated. Full article

Japanese knotweed (Fallopia japonica Houtt.) and Bohemian knotweed (Fallopia x bohemica) are invasive alien plant species, causing great global ecological and economic damage. Mechanical excavation of plant material represents an effective containment method, but it is not economically and environmentally sustainable as it produces an excessive amount of waste. Thus, practical uses of these plants are actively being sought. In this study, we explored the carotenoid profiles and carotenoid content of mature (green) and senescing leaves of both knotweeds. Both plants showed similar pigment profiles. By means of high performance thin-layer chromatography with densitometry and high performance liquid chromatography coupled to photodiode array and mass spectrometric detector, 11 carotenoids (and their derivatives) and 4 chlorophylls were identified in green leaves, whereas 16 distinct carotenoids (free carotenoids and xanthophyll esters) were found in senescing leaves. Total carotenoid content in green leaves of Japanese knotweed and Bohemian knotweed (378 and 260 mg of lutein equivalent (LE)/100 g dry weight (DW), respectively) was comparable to that of spinach (384 mg LE/100 g DW), a well-known rich source of carotenoids. A much lower total carotenoid content was found for senescing leaves of Japanese and Bohemian knotweed (67 and 70 mg LE/100 g DW, respectively). Thus, green leaves of both studied knotweeds represent a rich and sustainable natural source of bioactive carotenoids. Exploitation of these invaders for the production of high value-added products should consequently promote their mechanical control. Full article