Volatilome and flavor analyses based on e-nose combined with HS-GC-MS provide new insights into ploidy germplasm diversity in Platostoma palustre.

Platostoma palustre (Mesona chinensis Benth or Hsian-tsao, also known as "Xiancao" in China), is an edible and medicinal plant native to India, Myanmar, and Indo-China. It is the main ingredient in the popular desserts Hsian-tsao tea, herbal jelly, and sweet herbal jelly soup. P. palustre is found abundantly in nutrient-rich substances and possesses unique aroma compounds. Variations in the contents of volatile compounds among different germplasms significantly affect the quality and flavor of P. palustre, causing contradiction in demand. This study investigates the variation in the volatile compound profiles of distinct ploidy germplasms of P. palustre by utilising headspace gas chromatography-mass spectrometry (HS-GC-MS) and an electronic nose (e-nose). The results showed significant differences in the aroma characteristics of stem and leaf samples in diverse P. palustre germplasms. A total of sixty-seven volatile compounds have been identified and divided into ten classes. Six volatile compounds (caryophyllene, α-bisabolol, benzaldehyde, ß-selinene, ß-elemene and acetic acid) were screened as potential marker volatile compounds to discriminate stems and leaves of P. palustre. In this study, leaves of P. palustre showed one odor pattern and stems showed two odor patterns under the influence of α-bisabolol, acetic acid, and butyrolactone. In addition, a correlation analysis was conducted on the main volatile compounds identified by HS-GC-MS and e-nose. This analysis provided additional insight into the variations among samples resulting from diverse germplasms. The present study provides a valuable volatilome, and flavor, and quality evaluation for P. palustre, as well as new insights and scientific basis for the development and use of P. palustre germplasm resources.

Antioxidant and Cytotoxic Properties of Berberis vulgaris (L.) Stem Bark Dry Extract.

Berberis vulgaris (L.) has remarkable ethnopharmacological properties and is widely used in traditional medicine. The present study investigated B. vulgaris stem bark (Berberidis cortex) by extraction with 50% ethanol. The main secondary metabolites were quantified, resulting in a polyphenols content of 17.6780 ± 3.9320 mg Eq tannic acid/100 g extract, phenolic acids amount of 3.3886 ± 0.3481 mg Eq chlorogenic acid/100 g extract and 78.95 µg/g berberine. The dried hydro-ethanolic extract (BVE) was thoroughly analyzed using Ultra-High-Performance Liquid Chromatography coupled with High-Resolution Mass Spectrometry (UHPLC-HRMS/MS) and HPLC, and 40 bioactive phenolic constituents were identified. Then, the antioxidant potential of BVE was evaluated using three methods. Our results could explain the protective effects of Berberidis cortex EC50FRAP = 0.1398 mg/mL, IC50ABTS = 0.0442 mg/mL, IC50DPPH = 0.2610 mg/mL compared to ascorbic acid (IC50 = 0.0165 mg/mL). Next, the acute toxicity and teratogenicity of BVE and berberine-berberine sulfate hydrate (BS)-investigated on Daphnia sp. revealed significant BS toxicity after 24 h, while BVE revealed considerable toxicity after 48 h and induced embryonic developmental delays. Finally, the anticancer effects of BVE and BS were evaluated in different tumor cell lines after 24 and 48 h of treatments. The MTS assay evidenced dose- and time-dependent antiproliferative activity, which was higher for BS than BVE. The strongest diminution of tumor cell viability was recorded in the breast (MDA-MB-231), colon (LoVo) cancer, and OSCC (PE/CA-PJ49) cell lines after 48 h of exposure (IC50 < 100 µg/mL). However, no cytotoxicity was reported in the normal epithelial cells (HUVEC) and hepatocellular carcinoma (HT-29) cell lines. Extensive data analysis supports our results, showing a significant correlation between the BVE concentration, phenolic compounds content, antioxidant activity, exposure time, and the viability rate of various normal cells and cancer cell lines.

Cytotoxic effects of aporphine alkaloids from the stems and leaves of Stephania dielsiana Y.C.Wu.

Phytochemical studies of the stems and leaves of Stephania dielsiana Y.C.Wu yielded two new aporphine alkaloids (1 and 5), along with six known alkaloids (2-4 and 6-8). Their structures were characterised based on analyses of spectroscopic data, including one- and two-dimensional nuclear magnetic resonance (NMR) spectroscopy and high-resolution electrospray ionisation mass spectrometry (HR-ESI-MS). The cytotoxic activities of the isolated compounds against a small panel of tumour cell lines were assessed by MTS assay. Interestingly, compound 2 exhibited particularly strong cytotoxic activities against HepG2, MCF7 and OVCAR8 cancer cell lines, with IC50 values of 3.20 ± 0.18, 3.10 ± 0.06 and 3.40 ± 0.007 µM, respectively. Furthermore, molecular docking simulations were carried out to explore the interactions and binding mechanisms of the most active compound (compound 2) with proteins. Our results contribute to understanding the secondary metabolites produced by S. dielsiana and provide a scientific rationale for further investigations of cytotoxicity of this valuable medicinal plant.

High-density genetic map construction and QTL mapping of a zigzag-shaped stem trait in tea plant (Camellia sinensis).

The highly unique zigzag-shaped stem phenotype in tea plants boasts significant ornamental value and is exceptionally rare. To investigate the genetic mechanism behind this trait, we developed BC1 artificial hybrid populations. Our genetic analysis revealed the zigzag-shaped trait as a qualitative trait. Utilizing whole-genome resequencing, we constructed a high-density genetic map from the BC1 population, incorporating 5,250 SNP markers across 15 linkage groups, covering 3,328.51 cM with an average marker interval distance of 0.68 cM. A quantitative trait locus (QTL) for the zigzag-shaped trait was identified on chromosome 4, within a 61.2 to 97.2 Mb range, accounting for a phenotypic variation explained (PVE) value of 13.62%. Within this QTL, six candidate genes were pinpointed. To better understand their roles, we analyzed gene expression in various tissues and individuals with erect and zigzag-shaped stems. The results implicated CsXTH (CSS0035625) and CsCIPK14 (CSS0044366) as potential key contributors to the zigzag-shaped stem formation. These discoveries lay a robust foundation for future functional genetic mapping and tea plant genetic enhancement.

Starch and sucrose metabolism plays an important role in the stem development in Medicago sativa.

The forage quality of alfalfa (Medicago sativa ) stems is greater than the leaves. Sucrose hydrolysis provides energy for stem development, with starch being enzymatically converted into sucrose to maintain energy homeostasis. To understand the physiological and molecular networks controlling stem development, morphological characteristics and transcriptome profiles in the stems of two alfalfa cultivars (Zhungeer and WL168) were investigated. Based on transcriptome data, we analysed starch and sugar contents, and enzyme activity related to starch-sugar interconversion. Zhungeer stems were shorter and sturdier than WL168, resulting in significantly higher mechanical strength. Transcriptome analysis showed that starch and sucrose metabolism were significant enriched in the differentially expressed genes of stems development in both cultivars. Genes encoding INV , bglX , HK , TPS and glgC downregulated with the development of stems, while the gene encoding was AMY upregulated. Weighted gene co-expression network analysis revealed that the gene encoding glgC was pivotal in determining the variations in starch and sucrose contents between the two cultivars. Soluble carbohydrate, sucrose, and starch content of WL168 were higher than Zhungeer. Enzyme activities related to sucrose synthesis and hydrolysis (INV, bglX, HK, TPS) showed a downward trend. The change trend of enzyme activity was consistent with gene expression. WL168 stems had higher carbohydrate content than Zhungeer, which accounted for more rapid growth and taller plants. WL168 formed hollow stems were formed during rapid growth, which may be related to the redistribution of carbohydrates in the pith tissue. These results indicated that starch and sucrose metabolism play important roles in the stem development in alfalfa.

Climate of origin shapes variations in wood anatomical properties of 17 Picea species.

BACKGROUND: Variations in hydraulic conductivity may arise from species-specific differences in the anatomical structure and function of the xylem, reflecting a spectrum of plant strategies along a slow-fast resource economy continuum. Spruce (Picea spp.), a widely distributed and highly adaptable tree species, is crucial in preventing soil erosion and enabling climate regulation. However, a comprehensive understanding of the variability in anatomical traits of stems and their underlying drivers in the Picea genus is currently lacking especially in a common garden. RESULTS: We assessed 19 stem economic properties and hydraulic characteristics of 17 Picea species grown in a common garden in Tianshui, Gansu Province, China. Significant interspecific differences in growth and anatomical characteristics were observed among the species. Specifically, xylem hydraulic conductivity (Ks) and hydraulic diameter exhibited a significant negative correlation with the thickness to span ratio (TSR), cell wall ratio, and tracheid density and a significant positive correlation with fiber length, and size of the radial tracheid. PCA revealed that the first two axes accounted for 64.40% of the variance, with PC1 reflecting the trade-off between hydraulic efficiency and mechanical support and PC2 representing the trade-off between high embolism resistance and strong pit flexibility. Regression analysis and structural equation modelling further confirmed that tracheid size positively influenced Ks, whereas the traits DWT, D_r, and TSR have influenced Ks indirectly. All traits failed to show significant phylogenetic associations. Pearson's correlation analysis demonstrated strong correlations between most traits and longitude, with the notable influence of the mean temperature during the driest quarter, annual precipitation, precipitation during the wettest quarter, and aridity index. CONCLUSIONS: Our results showed that xylem anatomical traits demonstrated considerable variability across phylogenies, consistent with the pattern of parallel sympatric radiation evolution and global diversity in spruce. By integrating the anatomical structure of the stem xylem as well as environmental factors of origin and evolutionary relationships, our findings provide novel insights into the ecological adaptations of the Picea genus.

A dataset of 40'000 trees with section-wise measured stem diameter and branch volume from across Switzerland.

Estimating growing stock is one of the main objectives of forest inventories. It refers to the stem volume of individual trees which is typically derived by models as it cannot be easily measured directly. These models are thus based on measurable tree dimensions and their parameterization depends on the available empirical data. Historically, such data were collected by measurements of tree stem sizes, which is very time- and cost-intensive. Here, we present an exceptionally large dataset with section-wise stem measurements on 40'349 felled individual trees collected on plots of the Experimental Forest Management project. It is a revised and expanded version of previously unpublished data and contains the empirically derived coarse (diameter ≥7 cm) and fine branch volume of 27'297 and 18'980, respectively, individual trees. The data were collected between 1888 and 1974 across Switzerland covering a large topographic gradient and a diverse species range and can thus support estimations and verification of volume functions also outside Switzerland including the derivation of whole tree volume in a consistent manner.

Stem moisture content prediction model for Larix olgensis based on beta regression.

To investigate the longitudinal variation patterns of sapwood, heartwood, bark and stem moisture content along the trunk of artificial Larix olgensis, we constructed mixed effect models of moisture content based on beta regression by combining the effects of sampling plot and sample trees. We used two sampling schemes to calibrate the model, without limiting the relative height (Scheme Ⅰ) and with a limiting height of less than 2 m (Scheme II). The results showed that sapwood and stem moisture content increased gradually along the trunk, heartwood moisture content decreased slightly and then increased along the trunk, and bark moisture content increased along the trunk and then levelled off before increasing. Relative height, height to crown base, stand area at breast height per hectare, age, and stand dominant height were main factors driving moisture content of L. olgensis. Scheme Ⅰ showed the stable prediction accuracy when randomly sampling moisture content measurements from 2-3 discs to calibrate the model, with the mean absolute percentage error (MAPE) of up to 7.2% for stem moisture content (randomly selected 2 discs), and the MAPE of up to 7.4%, 10.5% and 10.5% for sapwood, heartwood and bark moisture content (randomly selected 3 discs), respectively. Scheme Ⅱ was appropriate when sampling moisture content measurements from discs of 1.3 and 2 m height and the MAPE of sapwood, heartwood, bark and stem moisture content reached 7.8%, 11.0%, 10.4% and 7.1%, respectively. The prediction accuracies of all mixed effect beta regression models were better than the base model. The two-level mixed effect beta regression models, considering both plot effect and tree effect, would be suitable for predicting moisture content of each part of L. olgensis well.

Adaptive strategies based on shrub leaf-stem anatomy and their environmental interpretations in the eastern Qaidam Basin.

BACKGROUND: Water stress seriously affects the survival of plants in natural ecosystems. Plant resistance to water stress relies on adaptive strategies, which are mainly based on plant anatomy with following relevant functions: (1) increase in water uptake and storage; (2) reduction of water loss; and (3) mechanical reinforcement of tissues. We measured 15 leaf-stem anatomical traits of five dominant shrub species from 12 community plots in the eastern Qaidam Basin to explore adaptive strategies based on plant leaf-stem anatomy at species and community levels. and their relationship with environmental stresses were tested. RESULTS: Results showed that the combination of leaf-stem anatomical traits formed three types of adaptive strategies with the drought tolerance of leaf and stem taken as two coordinate axes. Three types of water stress were caused by environmental factors in the eastern Qaidam Basin, and the established adaptive strategy triangle could be well explained by these environmental stresses. The interpretation of the strategic triangle was as follows: (1) exploitative plant strategy, in which leaf and stem adopt the hydraulic efficiency strategy and safety strategy, respectively. This strategy is mostly applied to plants in sandy desert (i.e., Nitraria tangutorum, and Artemisia sphaerocephala) which is mainly influenced by drought stress; (2) stable plant strategy, in which both leaf/assimilation branches and stem adopt hydraulic safety strategy. This strategy is mostly applied to plants in salty desert (i.e., Kalidium foliatum and Haloxylon ammodendron) which aridity has little effect on them; and (3) opportunistic plant strategy, in which leaf and stem adopt hydraulic safety strategy and water transport efficiency strategy. This strategy is mostly applied to plants in multiple habitats (i.e., Sympegma regelii) which is mainly affected by coldness stress. CONCLUSION: The proposed adaptive strategy system could provide a basis for elucidating the ecological adaptation mechanism of desert woody plants and the scientific management of natural vegetation in the Qinghai-Tibet Plateau.

Bulked Segregant RNA-Seq Reveals Different Gene Expression Patterns and Mutant Genes Associated with the Zigzag Pattern of Tea Plants (Camellia sinensis).

The unique zigzag-patterned tea plant is a rare germplasm resource. However, the molecular mechanism behind the formation of zigzag stems remains unclear. To address this, a BC1 genetic population of tea plants with zigzag stems was studied using histological observation and bulked segregant RNA-seq. The analysis revealed 1494 differentially expressed genes (DEGs) between the upright and zigzag stem groups. These DEGs may regulate the transduction and biosynthesis of plant hormones, and the effects on the phenylpropane biosynthesis pathways may cause the accumulation of lignin. Tissue sections further supported this finding, showing differences in cell wall thickness between upright and curved stems, potentially due to lignin accumulation. Additionally, 262 single-nucleotide polymorphisms (SNPs) across 38 genes were identified as key SNPs, and 5 genes related to zigzag stems were identified through homologous gene function annotation. Mutations in these genes may impact auxin distribution and content, resulting in the asymmetric development of vascular bundles in curved stems. In summary, we identified the key genes associated with the tortuous phenotype by using BSR-seq on a BC1 population to minimize genetic background noise.

In Vitro Inhibition of Colorectal Cancer Gene Targets by Withania somnifera L. Methanolic Extracts: A Focus on Specific Genome Regulation.

An approach that shows promise for quickening the evolution of innovative anticancer drugs is the assessment of natural biomass sources. Our study sought to assess the effect of W. somnifera L. (WS) methanolic root and stem extracts on the expression of five targeted genes (cyclooxygenase-2, caspase-9, 5-Lipoxygenase, B-cell lymphoma-extra-large, and B-cell lymphoma 2) in colon cancer cell lines (Caco-2 cell lines). Plant extracts were prepared for bioassay by dissolving them in dimethyl sulfoxide. Caco-2 cell lines were exposed to various concentrations of plant extracts, followed by RNA extraction for analysis. By explicitly relating phytoconstituents of WS to the dose-dependent overexpression of caspase-9 genes and the inhibition of cyclooxygenase-2, 5-Lipoxygenase, B-cell lymphoma-extra-large, and B-cell lymphoma 2 genes, our novel findings characterize WS as a promising natural inhibitor of colorectal cancer (CRC) growth. Nonetheless, we recommend additional in vitro research to verify the current findings. With significant clinical benefits hypothesized, we offer WS methanolic root and stem extracts as potential organic antagonists for colorectal carcinogenesis and suggest further in vivo and clinical investigations, following successful in vitro trials. We recommend more investigation into the specific phytoconstituents in WS that contribute to the regulatory mechanisms that inhibit the growth of colon cancer cells.

Positive contributions of the stem to the formation of white tea quality-related metabolites during withering.

Most teas, including white tea, are produced from tender shoots containing both leaf and stem. However, the effect of the stem on white tea quality remains unclear, especially during withering, an essential process. Therefore, this study investigated the withering-induced changes in the leaves and stems of Camellia sinensis cv. 'Fudingdabai' by multi-group analysis. During withering, the levels of catechin and theobromine (i.e., major flavor-related compounds) decreased slightly, mainly in the leaves. The abundance of some proteinaceous amino acids related to fresh taste increased in stems due to increased protein hydrolysis. In addition, changes in biosynthetic pathways caused a decrease in theanine (a major non-proteinaceous amino acid) and an increase in gamma-aminobutyric acid in stems. Terpenes, mainly in the stems, were partially affected by withering. Phenylacetaldehyde, a major contributor to white tea aroma, increased mainly in the stems. These findings reflect the positive contribution of the stem to white tea quality.

Identification and characterization of PAL genes involved in the regulation of stem development in Saccharum spontaneum L.

BACKGROUND: Saccharum spontaneum L. is a closely related species of sugarcane and has become an important genetic component of modern sugarcane cultivars. Stem development is one of the important factors for affecting the yield, while the molecular mechanism of stem development remains poorly understanding in S. spontaneum. Phenylalanine ammonia-lyase (PAL) is a vital component of both primary and secondary metabolism, contributing significantly to plant growth, development and stress defense. However, the current knowledge about PAL genes in S. spontaneum is still limited. Thus, identification and characterization of the PAL genes by transcriptome analysis will provide a theoretical basis for further investigation of the function of PAL gene in sugarcane. RESULTS: In this study, 42 of PAL genes were identified, including 26 SsPAL genes from S. spontaneum, 8 ShPAL genes from sugarcane cultivar R570, and 8 SbPAL genes from sorghum. Phylogenetic analysis showed that SsPAL genes were divided into three groups, potentially influenced by long-term natural selection. Notably, 20 SsPAL genes were existed on chromosomes 4 and 5, indicating that they are highly conserved in S. spontaneum. This conservation is likely a result of the prevalence of whole-genome replications within this gene family. The upstream sequence of PAL genes were found to contain conserved cis-acting elements such as G-box and SP1, GT1-motif and CAT-box, which collectively regulate the growth and development of S. spontaneum. Furthermore, quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis showed that SsPAL genes of stem had a significantly upregulated than that of leaves, suggesting that they may promote the stem growth and development, particularly in the + 6 stem (The sixth cane stalk from the top to down) during the growth stage. CONCLUSIONS: The results of this study revealed the molecular characteristics of SsPAL genes and indicated that they may play a vital role in stem growth and development of S. spontaneum. Altogether, our findings will promote the understanding of the molecular mechanism of S. spontaneum stem development, and also contribute to the sugarcane genetic improving.

Isotope Distribution Analysis in H218O Pulse-Labeled Trees Frozen with Liquid Nitrogen.

Tracer injection has long been recognized as a valuable tool for delineating tree hydraulics and assessing water transport pathways. Recently, isotope tracers have emerged as innovative instruments for investigating tree hydraulics, providing new insights into tree water dynamics. Nevertheless, there is a critical need for further research to comprehensively grasp water movement and distribution within trees. A previously introduced technique for analyzing the isotopic ratio of water in wet tissues, offering millimeter-scale resolution for visualizing tracer movement, faces challenges due to its underdeveloped sample preparation techniques. In this study, we introduced an H2 18O tracer into S. gracilistyla samples, exclusively comprising indeterminate roots, stems, and leaves, cultivated through hydroponics and grown within the current year. Our objective was to assess the axial distribution of the tracer in the xylem. Additionally, we devised a novel method for preparing frozen wet tissue samples, enhancing the repeatability and success rate of experiments. The results demonstrated that all frozen wet tissue samples exhibited an average water loss rate of less than 0.6%. Isotopic analysis of these samples unveiled a consistent decline in tracer concentration with increasing height in all Salix specimens, with three out of five samples revealing a significant isotope gradient. Our findings affirm the efficacy and practicality of combining isotopic labeling with freezing, stabilization, and preparation techniques. Looking ahead, our isotopic labeling and analysis methods are poised to transcend woody plants, finding extensive applications in plant physiology and ecohydrology.

Microbial communities of Schisandra sphenanthera Rehd. et Wils. and the correlations between microbial community and the active secondary metabolites.

Background: Schisandra sphenanthera Rehd. et Wils. is a plant used in traditional Chinese medicine (TCM). However, great differences exist in the content of active secondary metabolites in various parts of S. sphenanthera. Do microorganisms critically influence the accumulation of active components in different parts of S. sphenanthera? Methods: In this study, 16S/ITS amplicon sequencing analysis was applied to unravel microbial communities in rhizospheric soil and different parts of wild S. sphenanthera. At the same time, the active secondary metabolites in different parts were detected, and the correlation between the secondary metabolites and microorganisms was analyzed. Results: The major components identified in the essential oils were sesquiterpene and oxygenated sesquiterpenes. The contents of essential oil components in fruit were much higher than that in stem and leaf, and the dominant essential oil components were different in these parts. The dominant components of the three parts were γ-muurolene, δ-cadinol, and trans farnesol (stem); α-cadinol and neoisolongifolene-8-ol (leaf); isosapathulenol, α-santalol, cedrenol, and longiverbenone (fruit). The microbial amplicon sequences were taxonomically grouped into eight (bacteria) and seven (fungi) different phyla. Community diversity and composition analyses showed that different parts of S. sphenanthera had similar and unique microbial communities, and functional prediction analysis showed that the main functions of microorganisms were related to metabolism. Moreover, the accumulation of secondary metabolites in S. sphenanthera was closely related to the microbial community composition, especially bacteria. In endophytic bacteria, Staphylococcus and Hypomicrobium had negative effects on five secondary metabolites, among which γ-muurolene and trans farnesol were the dominant components in the stem. That is, the dominant components in stems were greatly affected by microorganisms. Our results provided a new opportunity to further understand the effects of microorganisms on the active secondary metabolites and provided a basis for further research on the sustainable utilization of S. sphenanthera.

In vitro Antibacterial Activity of Ethanolic Tanao Si Kan Dang RD1 (Cannabis sativa L.) Extracts Against Human Antibiotic-Resistant Bacteria.

<b>Background and Objective:</b> A new strain of cannabis, <i>Cannabis sativa</i> L. Tanao Si Kan Dang RD1, has been approved and registered by the Rajamangala University of Technology Isan, Thailand. The <i>C. sativa</i> is acknowledged for its medicinal properties which demonstrated various therapeutic properties, such as anti-cancer and antibacterial activities. This study aimed to investigate the antibacterial activity of ethanolic extracts from the stems and leaves of the Tanao Si Kan Dang RD1 strain against seven antibiotic-resistant bacteria. <b>Materials and Methods:</b> The primary antibacterial activity of ethanolic Tanao Si Kan Dang RD1 extracts were determined using the disc diffusion method, while the minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) were determined using the broth microdilution method. <b>Results:</b> The largest inhibition zone, measuring 12 mm, was observed in leaf extracts against <i>Pseudomonas aeruginosa</i> 101. The lowest MIC, at 0.78 mg/mL, was obtained from stem extracts against <i>Stenotrophomonas maltophilia</i>. The lowest MBCs, at 12.5 mg/mL, were observed in leaf extracts against <i>Enterococcus faecalis</i>, <i>Acinetobacter baumannii</i>, multidrug-resistant <i>Klebsiella</i> <i>pneumoniae</i>, <i>Stenotrophomonas maltophilia</i> and <i>Pseudomonas aeruginosa</i> 101 and stem extracts against <i>Acinetobacter baumannii</i>, multidrug-resistant <i>Klebsiella pneumoniae</i>, <i>Stenotrophomonas maltophilia</i> and <i>Pseudomonas aeruginosa</i> 101. <b>Conclusion:</b> This study presents a novel finding regarding the antibacterial activity of ethanolic extracts from the leaves and stems of Tanao Si Kan Dang RD1 against antibiotic-resistant bacteria. The potential application of these cannabis plant extracts in the development of antibiotics capable of combating antibiotic-resistant pathogenic bacteria represents a promising strategy to address a significant global health concern.

Effects of Selenium on the Lignin Deposition Pattern and Stem Mechanical Properties of Alfalfa (Medicago sativa L.).

Lignin provides structural support to plants; however, it reduces their utilization rate. According to our previous studies, selenium (Se) reduces lignin accumulation in alfalfa, but the specific mechanism involved remains unclear. Therefore, at the seedling stage, four root irrigation treatments using 2.5, 50, and 5 µmol/L sodium selenite (S-RI), selenomethionine (SS-RI), Se nanoparticles (SSS-RI), and deionized water (CK-RI) were performed. At the branching stage, four treatments of foliar spraying with the three Se fertilizers described above at a concentration of 0.5 mmol/L (S-FS, SS-FS, and SSS-FS) and deionized water (CK-FS) were administered. The results revealed that all Se treatments chiefly reduced the level of deposition of syringyl (S) lignin in the first internode of alfalfa stems. SS-FS and SSS-FS treatments mainly reduced the deposition of S and guaiacyl (G) lignins in the sixth internode of alfalfa stems, respectively, while S-FS treatment only slightly reduced the deposition of G lignin. S, SS, and SSS-RI treatments reduced the level of deposition of S and G lignins in the sixth internode of alfalfa stems. Se application increased plant height, stem diameter, epidermis (cortex) thickness, primary xylem vessel number (diameter), and pith diameter of alfalfa but decreased primary xylem area and pith parenchyma cell wall thickness of the first internode, and SS(SSS)-FS treatment reduced the mechanical strength of alfalfa stems. Therefore, Se application could decrease lignin accumulation by regulating the organizational structure parameters of alfalfa stems and the deposition pattern of the lignin monomers.

Gelselegine-gelsedine type bisindoles as well as the units from Gelsemium elegans with promoting proliferation of oral mucosa fibroblast cells.

Two undescribed bisindole alkaloids, gelseginedine A (1) and its rearranged gelseginedine B (2), and seven unreported gelselegine-type oxindole alkaloids (3-9) were isolated from the stems and leaves of Gelsemium elegans, together with five known alkaloids (10-14). Compounds 1 and 2 represented the first examples of gelselegine-gelsedine type alkaloids which bridged two units by a double bond. Their structures with absolute configurations were elucidated by means of HRESIMS, NMR and calculational chemistry. The performed bioassay revealed that 14 could promote the proliferation of human oral mucosa fibroblast cells.

Different responses of oxygen and hydrogen isotopes in leaf and tree-ring organic matter to lethal soil drought.

The oxygen and hydrogen isotopic composition (δ18O, δ2H) of plant tissues are key tools for the reconstruction of hydrological and plant physiological processes and may therefore be used to disentangle the reasons for tree mortality. However, how both elements respond to soil drought conditions before death has rarely been investigated. To test this, we performed a greenhouse study and determined predisposing fertilization and lethal soil drought effects on δ18O and δ2H values of organic matter in leaves and tree rings of living and dead saplings of five European tree species. For mechanistic insights, we additionally measured isotopic (i.e. δ18O and δ2H values of leaf and twig water), physiological (i.e. leaf water potential and gas-exchange) and metabolic traits (i.e. leaf and stem non-structural carbohydrate concentration, carbon-to-nitrogen ratios). Across all species, lethal soil drought generally caused a homogenous 2H-enrichment in leaf and tree-ring organic matter, but a low and heterogenous δ18O response in the same tissues. Unlike δ18O values, δ2H values of tree-ring organic matter were correlated with those of leaf and twig water and with plant physiological traits across treatments and species. The 2H-enrichment in plant organic matter also went along with a decrease in stem starch concentrations under soil drought compared with well-watered conditions. In contrast, the predisposing fertilization had generally no significant effect on any tested isotopic, physiological and metabolic traits. We propose that the 2H-enrichment in the dead trees is related to (i) the plant water isotopic composition, (ii) metabolic processes shaping leaf non-structural carbohydrates, (iii) the use of carbon reserves for growth and (iv) species-specific physiological adjustments. The homogenous stress imprint on δ2H but not on δ18O suggests that the former could be used as a proxy to reconstruct soil droughts and underlying processes of tree mortality.

Dry and wet periods determine stem and soil greenhouse gas fluxes in a northern drained peatland forest.

Greenhouse gas (GHG) fluxes from peatland soils are relatively well studied, whereas tree stem fluxes have received far less attention. Simultaneous year-long measurements of soil and tree stem GHG fluxes in northern peatland forests are scarce, as previous studies have primarily focused on the growing season. We determined the seasonal dynamics of tree stem and soil CH4, N2O and CO2 fluxes in a hemiboreal drained peatland forest. Gas samples for flux calculations were manually collected from chambers at different heights on Downy Birch (Betula pubescens) and Norway Spruce (Picea abies) trees (November 2020-December 2021) and analysed using gas chromatography. Environmental parameters were measured simultaneously with fluxes and xylem sap flow was recorded during the growing season. Birch stems played a greater role in the annual GHG dynamics than spruce stems. Birch stems were net annual CH4, N2O and CO2 sources, while spruce stems constituted a CH4 and CO2 source but a N2O sink. Soil was a net CO2 and N2O source, but a sink of CH4. Temporal dynamics of stem CH4 and N2O fluxes were driven by isolated emissions' peaks that contributed significantly to net annual fluxes. Stem CO2 efflux followed a seasonal trend coinciding with tree growth phenology. Stem CH4 dynamics were significantly affected by the changes between wetter and drier periods, while N2O was more influenced by short-term changes in soil hydrologic conditions. We showed that CH4 emitted from tree stems during the wetter period can offset nearly half of the soil sink capacity. We presented for the first time the relationship between tree stem GHG fluxes and sap flow in a peatland forest. The net CH4 flux was likely an aggregate of soil-derived and stem-produced CH4. A dominating soil source was more evident for stem N2O fluxes.