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Korean American Pioneer Aviators: The Willows Airmen is the untold story of the brave Korean men who took to the skies more than twenty years before the Tuskegee Airmen fought in World War II.The tale of the Willows Aviation School connects Korean, American, and Korean American aviation history.

Recreating everyday life in a mid-fourteenth century rural English village, the author focuses on the experiences of ordinary villagers as they lived and died during the Black Death (1345-50). Hatcher describes the day-to-day existence of people struggling with the tragic effects of the plague.

1. Climate warming is predicted to alter ecological boundaries in high-latitude ecosystems including the elevational or latitudinal extent of tall shrubs in Arctic and alpine tundra. Over 60 studies from 128 locations around the tundra biome have investigated shrub expansion in tundra ecosystems; however, only six studies test whether shrublines are actually advancing up hill-slopes or northward into tundra where tall shrubs are currently absent. 2. We test the hypothesis that willow shrublines have expanded to higher elevations in relation to climate across a 50 × 50 km area in the Kluane Region of the southwest Yukon Territory, Canada by surveying of 379 shrubs at 14 sites and sampling of 297 of the surveyed shrubs at 10 sites. We compared growth and recruitment to climate variables to test the climate sensitivity of shrub increase using annual radial growth analysis, age distributions and repeat field surveys to estimate the current rate of shrubline advance. 3. We found consistent and increasing rates of recruitment of alpine willows, with estimates of faster advancing shrublines on shallower hill-slopes. Mortality was extremely low across the elevation gradient. Aspect, elevation and species identity did not explain variation in recruitment patterns, suggesting a regional factor, such as climate, as the driver of the observed shrubline advance. 4. Annual radial growth of willows was best explained by variation in summer temperatures, and recruitment pulses by winter temperatures. Measured recruitment rates are ~20 ± 5 individuals per hectare per decade (M ± SE) and measured rates of increased shrub cover of ~5 ± 1% per decade (M ± SE) measured at the Pika Camp site between field surveys in 2009 and 2013. Our results suggest that shrubline will continue to advance over the next 50 years, if growing conditions remain suitable. However, if future conditions differ between summer and winter seasons, this could lead to contrasting trajectories for recruitment vs. growth, and influence the vegetation change observed on the landscape. 5. Synthesis. Our findings in the context of a review of the existing literature indicate that elevational and latitudinal shrublines, like treelines, are advancing in response to climate warming; however, the trajectories of change will depend on the climate drivers controlling recruitment vs. growth.

Salix species, including willow trees, are distributed in the temperate regions of Asian countries, including South Korea. Willow trees are used to treat pain and inflammatory diseases. Due to the medicinal properties of willow trees, pharmacological studies of other Salix spp. have gained attention; however, only a few studies have investigated the phytochemicals of these species. As part of our ongoing natural product research to identify bioactive phytochemicals and elucidate their chemical structures from natural resources, we investigated the marker compounds from indigenous Korean Salix species, namely, Salix triandra, S. chaenomeloides, S. gracilistyla, S. koriyanagi, S. koreensis, S. pseudolasiogyne, S. caprea, and S. rorida. The ethanolic extract of each Salix sp. was investigated using high-performance liquid chromatography combined with thin-layer chromatography and liquid chromatography–mass spectrometry-based analysis, and marker compounds of each Salix sp. were isolated. The chemical structures of the marker compounds (1–8), 3-(4-hydroxyphenyl)propyl β-D-glucopyranoside (1), 2-O-acetylsalicin (2), 1-O-p-coumaroyl glucoside (3), picein (4), isograndidentatin B (5), 2′-O-acetylsalicortin (6), dihydromyricetin (7), and salicin (8) were elucidated via nuclear magnetic resonance spectroscopy and high-resolution liquid chromatography–mass spectrometry using ultrahigh-performance liquid chromatography coupled with a G6545B Q-TOF MS system with a dual electrospray ionization source. The identified marker compounds 1–8 were examined for their antimicrobial effects against plant pathogenic fungi and bacteria. Dihydromyricetin (7) exhibited antibacterial activity against Staphylococcus aureus, inducing 32.4% inhibition at a final concentration of 125 μg/mL with an MIC[sub.50] value of 250 μg/mL. Overall, this study isolated the marker compounds of S. triandra, S. chaenomeloides, S. gracilistyla, S. koriyanagi, S. koreensis, S. pseudolasiogyne, S. caprea, and S. rorida and identified the anti-Staphylococcus aureus bacterial compound dihydromyricetin.

Polyploidy is common in the genus . However, little is known about the origin, parentage and genomic composition of polyploid species because of a lack of suitable molecular markers and analysis tools. We established a phylogenomic framework including species of all described sections of Eurasian shrub willows. We analyzed the genomic composition of seven polyploid willow species in comparison to putative diploid parental species to draw conclusions on their origin and the effects of backcrossing and post-origin evolution. We applied recently developed programs like SNAPP, HyDe, and SNiPloid to establish a bioinformatic pipeline for unravelling the complexity of polyploid genomes. RAD sequencing revealed 23,393 loci and 320,010 high quality SNPs for the analysis of relationships of 35 species of Eurasian shrub willows ( subg. ). Polyploid willow species appear to be predominantly of allopolyploid origin. More ancient allopolyploidization events were observed for two hexaploid and one octoploid species, while our data suggested a more recent allopolyploid origin for the included tetraploids and identified putative parental taxa. SNiPloid analyses disentangled the different genomic signatures resulting from hybrid origin, backcrossing, and secondary post-origin evolution in the polyploid species. Our RAD sequencing data demonstrate that willow genomes are shaped by ancient and recent reticulate evolution, polyploidization, and post-origin divergence of species.

Willows (Salix) are some of the most abundant shrubs in cold alpine and tundra biomes. In alpine regions, seed dispersal is not limiting upwards willow expansion, so the upslope shift of willow shrublines is assumed to be a response to climatic warming. Very little, however, is known about the recent spatiotemporal dynamics of alpine willow shrublines. The world's highest willow shrublines (ca 4900 m a.s.l.) are located on the Tibetan Plateau (TP) and provide a rare opportunity to test their sensitivity and responses to rapid warming and the associated increase in the demand for water in ecosystems. We used a new data set comprising 24 Salix shrubline plots along a 900‐km latitudinal gradient (30‒38°N) to reconstruct the rates of annual shrub recruitment and shifting shrubline positions since 1939. Shrub densification and shrubline advances were promoted by pronounced summer warming before 2010, contributing to widespread greening on the TP. These trends, however, reversed due to warming‐induced moisture limitation after 2010, which thus represented a tipping point of warming/drying trade‐offs. Climatic warming and drying are predicted to accelerate in the following decades, so alpine plant communities may be at an increasing risk of population decline or even range contraction.

An efficient in vitro propagation protocol has been established for a valuable medicinal plant, Salix tetrasperma using mature nodal explants. The investigation aimed to observe the influence of various combinations and concentrations of cytokinins (mT, BA, and Kn) and auxins (NAA, IAA, and IBA) on regeneration potential using the Murashige and Skoog (MS) medium. Among individual cytokinin treatments, 5.0 µM mT resulted highest response of 92% with maximum shoot number (11.6 ± 0.08) per explant and shoot length (4.5 ± 0.22 cm) after 12 weeks of culture. However, synergistic treatment of mT (5.0 µM) and NAA (0.5 µM) further improved proliferation with (21.3 ± 0.40) shoots per explant and (6.9 ± 0.13 cm) shoot length in 96% cultures after 12 weeks of incubation. Rooting from in vitro raised microshoots was achieved on ½ MS medium supplemented with various concentrations of low-dose auxins. The highest number of roots (10.4 ± 0.20) per shoot with mean root length (5.7 ± 0.11 cm) with maximum rooting frequency (97%) was observed in 0.5 µM IBA, after 4 weeks of culture. The rooted plantlets achieved a remarkable 86% survivability rate, when transferred to ex vitro conditions during acclimatization. Analysis of photosynthetic parameters and their characteristics during the acclimatization phase revealed a gradual decline in photosynthetic attributes during initial weeks; however, a significant improvement was noted as the growth proceeded. SEM analysis revealed the ultra-morphological structural differences between in vivo and in vitro derived leaves of S. tetrasperma . Moreover, DPPH assay observed differential antioxidant activity of in vitro raised plantlets throughout the acclimatization period. The GC-MS analysis from leaf extracts of donor plants and in vitro derived plantlets has revealed a broad spectrum of phytochemical compounds with significant pharmacological properties. No polymorphism in the banding pattern was found when the genetic fidelity of the regenerated plants was evaluated using SCoT primers, indicating the clonal stability of micropropagated plants. This study is the first to explore the use of mT in regeneration of S. tetrasperma , showing its more effectiveness than BA and Kn. Key message A reliable and more advanced in vitro protocol was established for Salix tetrasperma using cytokinin (mT), a novel aromatic cytokinin. This method led to significant improvement in multiple shoot formation and elongation, root development. Moreover, the assessment of transpiration rate (E), intercellular CO 2 concentrations (Ci), net photosynthetic rate (PN), stomatal conductance (gs), chlorophyll (Chl a/b), carotenoid content, phytochemical profile and total antioxidant activity during acclimatization ensures enhanced survivability of in vitro raised plants. Furthermore, the application of mT did not compromise the genetic fidelity of the regenerated plants.

Fast-growing species have been increasingly developed in recent years, and among them, those cultivated to obtain combustible woody biomass have shown rapid development. The purpose of this research study is to highlight the properties of the briquettes and pellets obtained from energetic willow compared to the briquettes and pellets obtained from oak biomass. Methodologies have been based on international standards and were used to find the physical, mechanical, and calorific properties of the two types of briquettes and pellets. The results did not highlight a significant difference between the two categories of briquettes and pellets obtained from the two hardwood species (energetic willow and oak). Characteristics such as the calorific value were 20.7 MJ/kg for native pellets and 21.43 MJ/kg for torrefied pellets of energetic willow, as well as the compressive strength of 1.02 N/mm[sup.2] , surpassed the same characteristics of briquettes and pellets obtained from oak biomass. Other characteristics of energetic willows, such as energetic density of 18.0 × 10[sup.3] MJ/m[sup.3] , splitting strength of 0.08 N/mm[sup.2] , shear strength of 0.86 N/mm[sup.2] , and abrasion of 1.92%, were favorably related to the oak biomass. The ecological analysis highlighted the high potential of the ecological willow in a period when the quantities of carbon dioxide released into the atmosphere by human activities are very high, and its sequestration by existing forests is insufficient. As a general conclusion of this research study, it can be stated that the two categories of briquettes and pellets obtained from the woody biomass of the energetic willow and oak species have similar characteristics, which can be used separately or together in ecological and sustainable combustion.

Background Melampsora spp. rusts are the greatest pathogen threat to shrub willow ( Salix spp.) bioenergy crops. Genetic resistance is key to limit the effects of these foliar diseases on host response and biomass yield, however, the genetic basis of host resistance has not been characterized. The addition of new genomic resources for Salix provides greater power to investigate the interaction between S. purpurea and M. americana , species commonly found in the Northeast US. Here, we utilize 3′ RNA-seq to investigate host-pathogen interactions following controlled inoculations of M. americana on resistant and susceptible F 2 S. purpurea genotypes identified in a recent QTL mapping study. Differential gene expression, network analysis, and eQTL mapping were used to contrast the response to inoculation and to identify associated candidate genes. Results Controlled inoculation in a replicated greenhouse study identified 19 and 105 differentially expressed genes between resistant and susceptible genotypes at 42 and 66 HPI, respectively. Defense response gene networks were activated in both resistant and susceptible genotypes and enriched for many of the same defense response genes, yet the hub genes of these common response modules showed greater mean expression among the resistant plants. Further, eight and six eQTL hotspots were identified at 42 and 66 HPI, respectively. The combined results of three analyses highlight 124 candidate genes in the host for further analysis while analysis of pathogen RNA showed differential expression of 22 genes, two of which are candidate pathogen effectors. Conclusions We identified two differentially expressed M. americana transcripts and 124  S. purpurea genes that are good candidates for future studies to confirm their role in conferring resistance.