Salix Species Research Articles

Characterization of the complete chloroplast genome and development of molecular markers of Salix

Salix, an economically and ecologically multifunctional tree species widely distributed in China, encompasses five ornamental species sequenced in this study, which are highly beneficial for plant phytoremediation due to their ability to absorb heavy metals. This research utilized high-throughput sequencing to acquire chloroplast genome sequences of Salix, analyzing their gene composition and structural characteristics, identifying potential molecular markers, and laying a foundation for Salix identification and resource classification. Chloroplast DNA was extracted from the leaves of Salix argyracea, Salix dasyclados, Salix eriocephala, Salix integra ‘Hakuro Nishiki’, and Salix suchowensis using an optimized CTAB method. Sequencing was conducted on the Illumina NovaSeq PE150 platform, and bioinformatics tools were employed to compare the structural features and variations within the chloroplast genomes of the Salix. Analysis revealed high similarity among the chloroplast genome sequences of the five Salix species, with a subsequent examination identifying 276, 269, 270, 273, and 273 SSR loci, respectively, along with unique simple repeat sequences in each variety. Comparison of chloroplast genomes across 22 Salix highlighted variations in regions such as matK-trnQ, ndhC-trnV, psbE-petL, rpl36-rps8, and ndhB-rps7, which may serve as valuable molecular markers for willow resource classification studies. In this study, chloroplast genome sequencing and structural analysis of Salix not only enhances the genetic resources of Salix but also forms a critical basis for the development of molecular markers and the exploration of interspecific phylogeny in the genus.

Advancing woody plant regeneration: Insights from salix species tissue culture studies

Abstract. In this study, we established a sterile propagation and regeneration system for Mongolian willow in order to study its salt tolerance and adaptation in depth and to provide methods for future genetic improvement. Mongolian willow, belonging to the genus Willow in the family Populus, is valued for its high salt tolerance and ability to ameliorate high pH soils. However, its distribution in specific saline soil areas and sensitivity to drought and rainless environments make its reproduction limited. In this study, by stem segment induction method, we aseptically cultured apical and lateral shoots of Mongolian willow, respectively, and found that the apical shoots performed best in MS medium supplemented with 0.1 mg/L IBA, while the lateral shoots grew well in MS medium supplemented with 6-BA, IBA and TDZ. In addition, this study investigated the effects of different combinations of phytohormones on healing tissue induction and found that the combination of NAA and 6-BA had the highest success and value-added rate. Further addition of TDZ significantly increased the induction rate. The study also dealt with the application of DNA methylation inhibitors in inducing adventitious shoots, and the results showed that the addition of this inhibitor in specific culture medium could significantly increase the induction rate of adventitious shoots. In this study, the regeneration system of Mongolian willow was successfully established, which provides a basis for its future genetic research and wide application.

Phenophases of Species of the Salix Genus in the Conditions of Osh City

The study of the phenology of urban trees and shrubs has increased dramatically worldwide in recent years, as changes in plant phenology may indicate the impacts of climate change at different scales. The aim of the study is to determine the patterns of the seasonal rhythm of individual species belonging to the Salixgenus in Osh. The studies were conducted in the period 2019-2023 at the Department of Biology, Chemistry and Nature Management of Osh State Pedagogical University. The subject of the study is 4 species of the genus Salix: Salix babylonica L., Salix turanica Nasarow, Salix wilhelmsiana M. Bieb. and Salix tenuijulis Ledeb. Phenological observations were carried out for 5 years using generally accepted phenological methods. The results of phenological observations in 2019-2023 show that the duration of the growing season in urban conditions is 240-245 days, and this indicator varies depending on climatic conditions. The observed species have differences in the flowering sequence, the beginning and duration of flowering. The total duration of flowering in the studied species is 25-35 days. The seasonal type of growth and phenological development of plants of the genus Salix is characterized by an early onset and late end of vegetation, stability of average phenological terms. Such a phenological rhythm of the studied species of the genus Salix makes it possible to consider cultivation for decorative and environmental purposes in urban conditions promising.

Polyphenol Analysis and Antibacterial Potentials of Twig Extracts of Salix aurita, S. pyrolifolia, and S. caprea Growing Naturally in Finland.

Salix species have been used in traditional medicine to treat fever and inflammation. However, there is no reported information on the antibacterial activities of S. aurita and S. pyrolifolia, and little is known about the phytochemistry of S. aurita. In this study, winter-dormant twig extracts of S. aurita, S. caprea, and S. pyrolifolia were screened for their antibacterial activities against Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus cereus, and Escherichia coli. The antibacterial effects were evaluated using agar diffusion and turbidimetric microplate methods. Time-kill effects were measured using the microplate optical density (OD620) method. UPLC-PDA-QTOF/MS analysis was conducted to identify the polyphenols present in a methanol extract of S. aurita. The antibacterial results show that methanol and hot and cold water twig extracts of S. aurita, S. caprea, and S. pyrolifolia have significant antibacterial effects against P. aeruginosa, S. aureus, and B. cereus with the diameters of the inhibition zones (IZDs) ranging from 16.17 to 30.0 mm and the MICs between 1250 and 2500 µg/mL. Only the cold water extract of S. caprea was moderately active against E. coli. Proanthocyanidins, procyanidin B1 (m/z 577), and procyanidin C1 (m/z 865) were identified as the major polyphenols present in the methanol extract of S. aurita twigs for the first time. Additionally, salicin-7-sulfate was present in S. aurita twigs. Procyanidin B-1, taxifolin, trans-p-hydroxycinnamic acid, and catechin showed growth inhibitory activity against B. cereus with a MIC value of 250 µg/mL.

Carboxylation capacity is the main limitation of carbon assimilation in High Arctic shrubs.

Increases in shrub height, biomass and canopy cover are key whole-plant features of warming-induced vegetation change in tundra. We investigated leaf functional traits underlying photosynthetic capacity of Arctic shrub species, particularly its main limiting processes such as mesophyll conductance. In this nutrient-limited ecosystem, we expect leaf nitrogen concentration to be the main limiting factor for photosynthesis. We measured the net photosynthetic rate at saturated light (Asat) in three Salix species throughout a glacial valley in High-Arctic tundra and used a causal approach to test relationships between leaf stomatal and mesophyll conductances (gsc, gm), carboxylation capacity (Vcmax), nitrogen and phosphorus concentration (Narea, Parea) and leaf mass ratio (LMA). Arctic Salix species showed no difference in Asat compared to a global data set, while being characterized by higher Narea, Parea and LMA. Vcmax, gsc and gm independently increased Asat, with Vcmax as its main limitation. We highlighted a nitrogen-influenced pathway for increasing photosynthesis in the two prostrate mesic habitat species. In contrast, the erect wetland habitat Salix richardsonii mainly increased Asat with increasing gsc. Overall, our study revealed high photosynthetic capacities of Arctic Salix species but contrasting regulatory pathways that may influence shrub ability to respond to environmental changes in High Arctic tundra.

Divergent hydraulic and gas exchange strategies in two closely-related Salix species

Abstract Understanding the physiological mechanisms that trees employ to cope with drought-induced mortality is crucial for predicting their responses to a changing climate. Salix species exhibit distinct habit distributions, with Salix babylonica growing in wet habitats and S. matsudana growing in relatively dry habitats. The objective of this study was to compare hydraulic and gas exchange traits between these two closely-related Salix species with contrasting natural habitats. S. matsudana had lower photosynthesis (Amax), lower stomatal conductance (gs), and lower stem and leaf hydraulic conductance, but it exhibited higher water use efficiency (WUEi), higher hydraulic safety and wider leaf-to-stem vulnerability segmentation as well as narrower, shorter and denser conduits and a lower ratio of leaf area to sapwood area than S. babylonica. These findings suggest that variation in hydraulic vulnerability and gas exchange traits enable closely-related Salix species to adapt to different habitats.

Genetic structure and gene flow among populations of willow (Salix species)

The newly developed Salix hybrids were assessed for genetic diversity using ISSR (Inter Simple Sequence Repeats) molecular markers. The results revealed 88.08 polymorphism, 0.53 polymorphism information content, 4.70 effective multiplex ratio, 2.54 marker index, and 7.18 resolving power from the amplified primers. Clones of the Salix matsudana (MAT) population recorded a maximum mean number of effective alleles (1.42), Shannon information index (0.38), gene diversity (0.25), and percentage of polymorphic loci (82.24 %). The AMOVA (Analysis of molecular variance) results revealed a moderate genetic divergence with a genetic variation of 88 per cent within populations and 12 per cent among the populations. The highest value of total diversity (0.28) and gene diversity (0.24) was recorded between S. matsudana (MAT) and S. tetrasperma (TETRA) populations, while there was more gene flow between S. matsudana (MAT) and S. tetrasperma (TETRA) populations (5.86). The clustering pattern obtained through STRUCTURE software showed two main gene pools and a mixture of 6–7 gene pools to confirm the hybrids based on ISSR marker data. S. matsudana and S. tetrasperma clones showed the highest gene diversity due to their proximity from their original locations, resulting in the least amount of gene exchange among populations. Molecular characterization using ISSR markers was extremely useful for studying the genetic diversity among the willow hybrids and high genetic variability should be utilized for breeding purposes in the future.

High cadmium-accumulating Salix ecotype shapes rhizosphere microbiome to facilitate cadmium extraction

Cadmium (Cd) contamination poses a significant threat to agricultural soils and food safety, necessitating effective remediation strategies. Salix species, with their high coverage and Cd accumulating capacity, hold promise for remediation efforts. The rhizosphere microbiome is crucial for enhancing Cd accumulating capacity for Salix. However, the mechanisms by how Salix interacts with its rhizosphere microbiome to enhance Cd extraction remains poorly understood. In this study, we compared the remediation performance of two Salix ecotypes: 51–3 (High Cd-accumulating Ecotype, HAE) and P646 (Low Cd-accumulating Ecotype, LAE). HAE exhibited notable advantages over LAE, with 10.80 % higher plant height, 43.80 % higher biomass, 20.26 % higher Cd accumulation in aboveground tissues (93.09 μg on average), and a superior Cd translocation factor (1.97 on average). Analysis of the rhizosphere bacterial community via 16S rRNA amplicon sequencing revealed that HAE harbored a more diverse bacterial community with a distinct composition compared to LAE. Indicator analysis identified 84 genera specifically enriched in HAE, predominantly belonging to Proteobacteria, Actinobacteria, and Firmicutes, including beneficial microbes such as Streptomyces, Bacillus, and Pseudomonas. Network analysis further elucidated three taxa groups specifically recruited by HAE, which were highly correlated with functional genes that associated with biosynthesis of secondary metabolites, glycan biosynthesis and metabolism, and metabolism of cofactors and vitamins. These functions contribute to enhancing plant growth, Cd uptake, and resistance to Cd in Salix. Overall, our findings highlight the importance of the rhizosphere microbiome in facilitating Cd extraction and provide insights into microbiome-based strategies for sustainable agricultural practices.

Polyphenols and Phenolic Glucosides in Antibacterial Twig Extracts of Naturally Occurring Salix myrsinifolia (Salisb.), S. phylicifolia (L.) and S. starkeana (Willd.) and the Cultivated Hybrid S. x pendulina (Wender.).

(1) Background: Salix species occurring in Finland have not been well studied for their antimicrobial potential, despite their frequent use for lung and stomach problems in traditional medicine. Thus, twig extracts of three species of Salix that are found naturally in Finland and one cultivated species were screened for their antimicrobial properties against human pathogenic bacteria. S. starkeana and S. x pendulina were screened for antibacterial effects for the first time. (2) Methods: An agar diffusion and a microplate method were used for the screenings. Time-kill effects were measured using a plate-count and a microplate method. A DPPH-method using a qualitative TLC-analysis was used to detect antioxidant compounds in antimicrobial extracts. Metabolites from a S. myrsinifolia extract showing good antibacterial effects were identified using UPLC/QTOF-MS. (3) Results: A methanol extract of S. starkeana was particularly active against B. cereus (MIC 625 µg/mL), and a methanol extract of S. myrsinifolia showed good activity against S. aureus and B. cereus (MIC 1250 µg/mL) and showed bactericidal effects during a 24 h incubation of B. cereus. Moreover, a decoction of S. myrsinifolia resulted in good growth inhibition against P. aeruginosa. Our UPLC/QTOF-MS results indicated that proanthocyanidins (PAs), and especially the dimer procyanidin B1 (m/z 577) and other procyanidin derivatives, including highly polymerized proanthocyanidins, were abundant in S. myrsinifolia methanol extracts. Procyanidin B1 and its monomer catechin, as well as taxifolin and p-hydroxycinnamic acid, all present in S. myrsinifolia twigs, effectively inhibited B. cereus (MIC 250 µg/mL). (4) Conclusions: This study indicates that Finnish Salix species contain an abundance of antibacterial condensed tannins, phenolic acids and other polyphenols that deserve further research for the antibacterial mechanisms of action.

Salix species and varieties affect the molecular composition and diversity of soil organic matter

Abstract Background and aims Most studies of the relationships between the composition of soil organic matter and plant cover have been carried out at the plant genera level. However, they have largely overlooked the potential effects that plant varieties, belonging to the same genus, can have on soil organic matter. Methods We investigated whether plant varieties belonging to different Salix species (S. dasyclados and S. viminalis) impacted the composition of organic matter using mid-infrared spectroscopy and pyrolysis GC/MS. Top-soils were taken from an 18 year-old long-term field trial where six Salix varieties were grown as short-rotation coppice under two fertilisation regimes. Results Significant differences in the molecular composition and diversity of the soil organic matter were observed in the fertilised plots. The effects were mostly visible at the species level, i.e. the organic matter in soil under S. dasyclados varieties had higher molecular diversity and lignin content than under S. viminalis, potentially due to differences in the amount and composition of their litter inputs. Smaller differences among varieties from the same species were also observed. No significant effects of Salix varieties were observed in the unfertilised plots. The relatively high degree of spatial variability of several soil properties found in these plots may have masked plant variety and/or species effects. Conclusion This study provides evidence that the identity of Salix species or varieties can affect the molecular composition and diversity of soil organic matter. The corresponding traits should be considered in breeding programmes to enhance soil organic C accumulation and persistence.

Biomass Production and Metal Remediation by Salix alba L. and Salix viminalis L. Irrigated with Greywater Treated by Floating Wetlands

As an alternative wood source for biochar and a cost-effective renewable energy source, sustainable biomass production based on fast-growing willows irrigated with treated wastewater has been explored. Salix alba L. and Salix viminalis L. were selected for assessment of their potentially high woody biomass productivity and phytoremediation efficiency when irrigated with greywater treated by floating treatment wetlands. Both Salix species produced significantly (p < 0.05) high woody biomass in the second harvest, with a significantly higher fresh woody biomass weight with higher water content (53%) for S. viminalis compared to S. alba. The dry biomass weight of S. alba was greater than of S. viminalis at the first harvest. The element accumulations in substrates changed significantly after irrigation, with greywater compared to the raw substrate following this order: Mg > Fe > Al > Cr > Mn > Cd > Cu > B. Element concentrations accumulated in twigs of S. alba following this order: Ca > Mg > Na > Mn > Zn > Fe > Al > Cd > Cu > Cr > Ni > B, but for S. viminalis the order was Ca > Mg > Mn > Zn > Na > Fe > Al > Cd > Cu > Ni > Cr > B. The accumulations of Al, B, Ca, Fe, Mg, Mn, and Ni were significantly greater in S. alba leaves compared to their twigs, which showed significantly high accumulations of Na and Zn. The accumulations of Al, B, Ca, Fe, Mg, Mn, and Na were significantly greater in S. viminalis leaves compared to their twigs.

Yield, carbon stock, and price dynamics of agroforestry tree species in district Mardan, Khyber Pakhtunkhwa, Pakistan.

A socio-economic study was conducted in district Mardan of the Khyber Pakhtunkhwa (KP) province of Pakistan to get a comprehensive knowledge of the agroforestry tree species grown on the farmlands, their yield, and carbon stock. For yield and carbon stock estimation, data were collected from 59 sample plots by measuring the diameter, height, volume, and biomass of selected agroforestry tree species through D-tape and Haga altimeter. A total of 59 sample plots were inventoried using 2.5 percent sampling intensity. Each sample plot has an area of 0.5 ha, where each tree with a Diameter at Breast Height (DBH) ≥ 5 cm was inventoried. The calculated amount of volume of each tree species was then converted to biomass by multiplying it by the density of wood and the Biomass Expansion Factor (BEF). Total yield and C stock for the selected agroforestry tree species were 11535.2 metric tons and 2102.2 metric tons, respectively. Populus euroamericana is classified as the main tree with 28% growing stock prior to Morus alba by 21%, while Melia azedarach, Eucalyptus camaldulensis, Dalbergia sissoo, Acacia nilotica, Salix tetrasperma, and Bombax ceiba consist of 15%, 12%, 8%, 6%,7% and 3% growing stock respectively. Among the species found in different sampling plots the yield of Populus euroamericana was found to be 4747.5 metric tons and it was followed by the species Morus alba found at 2027.3 metric tons. Similarly, the volume for Melia azedarach, Eucalyptus camaldulensis, Dalbergia sissoo, Salix spp, Boombox ceiba, and Acacia nilotica was 1532.2 tons,1503 ton,745.7,203.5ton, 555.4ton and 220.5ton, respectively. The carbon stock for Populus euroamericana was calculated as 777.8 ton/ha, while for Eucalyptus camaldulensis, Melia azedarach, Morus alba, Dalbergia sissoo, Acacia nilotica, Salix species, and Bombax ceiba it was calculated as 312.3ton/ha, 272.1ton/ha, 363ton/ha, 245.1ton/ha, 51.4ton/ha, 27.3ton/ha and 53.2ton/ha, respectively. The questionnaire survey conducted for price dynamics showed that the majority of respondents purchase timber from the market for construction. But they use farm trees with low-quality city construction. They dislike using local timber in the conventional building as timber from farm trees is liable to insect attack. Rs. 50,000-100000, (33.33%) of daily sales was concluded from 50% of the trader while (16.7%) of the traders have their sales between Rs.150,000-200,000. Therefore, it is concluded by the authors that both provincial and federal government should promote agroforestry in Pakistan through different incentives because it has the potential to cope with dilemma of deforestation of natural forests and improve the livelihood of local peoples. It is strongly recommended that special projects just like the Ten Billion Tree Afforestation Project (T-BTTP) should be launched for agroforestry plantation and promotion in the country to sustain the ecological harmony and uplift the socio-economic condition of the peoples of Pakistan.

European Spongy moth (Lymantria dispar) (Lepidoptera) outbreaks in some regions of European Russia in 2023

A study was conducted to investigate the distribution and significant increase in the abundance of Lymantria dispar within the forest-steppe zone of European Russia, encompassing the regions of Ryazan, Moscow, Vladimir, and Ulyanovsk. The examination of hotspots associated with this pest during the year 2023 involved an analysis of data derived from diverse sources. The investigation encompassed an assessment of plant species that either attracted or repelled the pest’s caterpillars under natural conditions. The defoliation phenomenon was observed to vary across distinct plant species, with notable instances of extensive destruction identified on Betula, Quercus robur, Populus tremula, and various Salix species at multiple observation plots. Conversely, conifers such as Larix sibirica, Picea abies, Pinus sylvestris, and certain invasive (introduced) species, including Acer negundo, Elaeagnus argentea, Hirrarchaea rhamnoides, and Syringa vulgaris, exhibited an absence of caterpillar presence.

Закономерности роста видов Salix под влиянием природно-антропогенных факторов в городском парке Вольска

The article establishes the regularities of growth and development of tree-like willows growing in the city park of the city of Volsk under the influence of various water sources. The research methodology was based on the relevant GOST standards, recommendations of scientific institutions and scientific research. The variance analysis of the annual increments of 12 Salix species allowed us to establish patterns depending on the moisture content of the growing seasons of 2018, 2019 and 2022. It is determined that under natural conditions of humidification, the values of the willow branches’ increments in length depend on weather conditions, the lower the hydrothermal coefficient, the smaller the increments. Pond, stream, ground water available for roots increase the increments of Salix species up to 78.7%. The variance analysis of two-factor experience has established significant differences in both factors and their interaction. Regression and correlation analysis revealed that annual increases by 83% depend on weather conditions and the type of water source. It was revealed that the best tree-like willows growing on the territory of the park of culture and recreation in the city of Volsk are the following species: Salix babylonica var.tortuosa x alba var.recticapus (S. X ‘Sverdlovskaja Isvilistaja 2’ V. Schaburov et I. Beljaeva), Salix schwerinii x dasyclados (S. X ‘Rekord’ V. Schaburov et I. Beljaeva), Salix hybrida “Schater 1”, Salix matsudana Koidz., S. schwerini x (schwerinii x udensis) (S. x ‘Schwerina Ulutschennaja’ V. Schaburov et I. Beljaeva).

First report of Melampsora ferrinii (pucciniales) on Babylon willow (Salix babylonica) in Iran

As an agroforestry resource willow species (Salix spp.) becoming increasingly important in the protection of riverbanks, recovery of floodable lands, soil bioremediation, biomass production, and wicker furniture manufacture, Babylon willow (Salix babylonica) is widely planted all over the world and is found throughout Iran as part of the rural landscape and is mostly planted for ornamental or bioremediation purposes. Rust fungi in the genus Melampsora usually cause disease on Salix species. Identification of Melampsora species is often complicated because there are few differences in spore morphology and little publicly available comparative sequence data. Willow trees in Iran have been reported to be infected by 15 Melampsora species; however, most of these records are based on morphological characterization. During surveillance activities carried out in June 2007, a rust species was detected on isolated Babylon willow trees in an area in Northern Iran. Both the rust fungus and the host plant were identified on the basis of morphological features and DNA sequencing. Based on a combination of morphology, large subunit (LSU) rDNA sequencing and phylogenetic analyses, our rust specimen was identified as Melampsora ferrinii, which is newly reported from Iran on Salix babylonica. Melampsora ferrinii was originally described from the Americas and this is the first time this rust has been observed on its telial host, Babylon willow, in Asia. The documentation of the rust fungus was performed using both scanning electron microscopy (SEM) and light microscopy. Additionally, an identification key for Melampsora species reported on Salix spp. in Iran is included.

Genome-Wide Identification of Pleiotropic Drug Resistance (PDR) Transporters in Salix purpurea and Expression Analysis in Response to Various Heavy Metal Stresses

Pleiotropic drug resistance (PDR) transporters, which are part of the ABCG subfamily of ATP-binding cassette (ABC) transporters, have been found to be involved in heavy metal tolerance. Salix species (willow) is widely regarded as a perfect candidate for phytoremediation of heavy metals because of its substantial biomass, strong tolerance, and remarkable capacity to accumulate heavy metals. However, the phylogeny and mechanisms underlying the response to heavy metals within the PDR family in willow have yet to be determined. In this study, we discovered and valuated a total of 21 PDR genes in the genome of Salix purpurea. The phylogenetic relationships of these genes were used to classify them into five major clades. The SpPDRs exhibited variations in exon-intron distribution patterns and gene lengths across different branches. Cis-acting elements linked to stress response, drought induction, low temperature, and defense response were discovered in the promoters of PDRs. Significant variations in the transcription levels of various PDR genes were observed across different tissues under heavy metal stress, with distinct heavy metals regulating different PDR members. In roots, PDR4 and PDR21 exhibited high expression levels. Meanwhile, PDR7 and PDR17 showed similar transcription patterns across all analyzed tissues. Furthermore, there was a significant and positive correlation between PDR5 and PDR16, whereas a significant and negative correlation was detected between PDR3 and PDR9, suggesting that the response of PDR members to heavy metals is complex and multifaceted. These findings will establish a vital basis for comprehending the biological functionalities of PDR genes, specifically their involvement in the regulation of willow’s tolerance to heavy metals.

Inter- and intraspecific diversity of Salix bark phenolic profiles – A resource for the pharmaceutical industry

Due to their content of phenolic compounds, willow bark preparations are used as an herbal remedy. The large diversity of phenolic secondary metabolites in Salix still provides a resource for the identification of bioactive compounds in particular species, including species not yet in focus from a phytopharmaceutical perspective. The present study describes the bark phenolic profile of 13 Salix species analyzed by HPLC-MS: Salix alba, Salix babylonica, Salix daphnoides, Salix fragilis, Salix hastata, Salix myrsinifolia, Salix pentandra, Salix purpurea, Salix repens (including subspecies S. repens ssp. arenaria and S. repens ssp. repens), Salix rosmarinifolia, Salix sachalinensis, Salix triandra and Salix viminalis. The analyzed profiles comprised the chemical groups of salicylates, flavonoids, procyanidins, phenolic acid derivatives, and some unclassified phenolics. Particular compounds were detected in species where they have not been previously reported. Apart from interspecific diversity, qualitative variability within species was observed as certain components were detected only in some of the analyzed genotypes. The knowledge on specific phenolic profiles of species and genotypes is the basis for the selection of suitable willow bark material with certain desired bioactive properties. Furthermore, the high inter- and intraspecific variability points out the necessity for product standardization of willow bark raw material.

Phytochemical and Antioxidant Characterization of Extracts from Unexplored Medicinal Plants Salix schwerinii and Salix kochiana

For a long time, species of the genus Salix have been widely utilized and studied as medicinal plants; however, the biological activity and phytochemical composition of Salix schwerinii (SS) and S. kochiana (SK) have not been studied at all. This study investigated the antioxidant properties of SS and SK extracts and detected phytochemical compounds in the extracts. The results showed that the antioxidant activities (IC50) of SS extract, SK extract, and ascorbic acid (reference) were as follows, respectively: 169.8, 79.8, and 71.2 μg mL−1 for ABTS cation radical scavenging and 38.4, 26.2, and 9.3 μg mL−1 for DPPH free radical scavenging. The results imply that SK has a high potential as a natural antioxidant. The phytochemical compositions of extracts (mg g−1) were analyzed as follows: SS extracts, 217.7 phenolics (1.54 catechin, 0.86 syringic acid, 0.46 luteolin, and others) and 5.06 salicin; SK extracts, 71.0 phenolics (0.54 catechin, 0.28 myricetin, 0.12 salicylic acid, and others) and 2.11 salicin. Compared to previous studies, the present findings go further to highlight that SS deserves attention as a novel source of salicin. The present study highlights the need for further studies on the aspects of medicinal functions of the extracts, bioprocess design for efficient phytochemical extraction, and applications of bioactive substances.

Palaearctic willow-catkin sawflies: a revision of the amentorum species group of Euura (Hymenoptera, Tenthredinidae)

The Euura amentorum species group is Holarctic, and in Europe it is most species-rich in the North. Their larvae develop entirely within the female catkins of Salix species: some species bore in the central stalk, whereas others live outside this and feed mainly on the developing seeds. Eight Palaearctic species are treated here as valid, and a key to these is provided. Males of five species are known. Two new species are described from northern Europe: Euura pohjola sp. n. and E. ursaminor sp. n. First records of E. itelmena (Malaise, 1931) from the West Palaearctic are presented. We propose seven new synonymies: Pontopristia montana Lindqvist, 1961 (junior secondary homonym in Euura) with Euura freyja (Liston, Taeger & Blank, 2009); Pontopristia brevilabris Malaise, 1921, Amauronematus fennicus Lindqvist, 1944, Pontopristia boreoalpina Lindqvist, 1961, Pontopristia punctulata Lindqvist, 1961, and Amauronematus pyrenaeus Lacourt, 1995 with Euura microphyes (Förster, 1854); and Pteronidea holmgreni Lindqvist, 1968 with Nematus umbratus Thomson, 1871. Lectotypes are designated for: Amauronematus fennicus Lindqvist, 1944, Nematus amentorum Förster, 1854, Nematus suavis Ruthe, 1859, Pontopristia brevilabris Malaise, 1921, Pontopristia itelmena Malaise, 1931, Pontopristia kamtchatica Malaise, 1931, Pontopristia lapponica Malaise, 1921, Pontopristia latiserra Malaise, 1921, Pontopristia romani Malaise, 1921, and Pristiphora amentorum var. nigripleuris Enslin, 1916. Many new host plant associations are recorded.

Phytochemical Screening of Ultrasonic Extracts of Salix Species and Molecular Docking Study of Salix-Derived Bioactive Compounds Targeting Pro-Inflammatory Cytokines.

Willow bark (Salix spp., Salicaceae) is a traditional analgesic and antirheumatic herbal medicine. The aim of this study was to evaluate and compare the phytochemical and antioxidant profiles of leaf and bark extracts of six species of the genus Salix obtained by ultrasound-assisted extraction (UAE) and to examine the inhibitory potential of target bioactive compounds against two inflammatory mediators, tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6), through in silico molecular docking. The total phenolic and flavonoid content of the extracts was estimated using spectrophotometric methods and the antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH•) and hydroxyl radical (•OH) scavenging assays. Chemical profiling of extracts was carried out using high-performance liquid chromatography coupled with a diode array detector (HPLC-DAD). Principal component analysis (PCA) was performed to differentiate the sample extracts based on their phytochemical profiles and amounts of target bioactive compounds. Chemical composition varied among the analyzed willow species and also among the plant organs of the same species. The major bioactive compounds of the extracts were salicin, chlorogenic acid, rutin and epicatechin. The extracts exhibited significant DPPH● and ●OH scavenging activities. Results of molecular docking revealed that chlorogenic acid had the highest binding affinity toward TNF-α and IL-6. UAE extracts represent valuable sources of antioxidant and anti-inflammatory compounds.