Heartwood Formation Research Articles

Rapid identification and on-site analysis by miniature mass spectrometry of chemical markers for fragrant rosewood authentication

Dalbergia odorifera T. Chen (Dalbergiae Odoriferae Lignum, DOL), renowned for its therapeutic applications in traditional Chinese medicine and its value in crafting luxury items, faces challenges due to the slow heartwood formation process and subsequent market adulteration. The proliferation of counterfeit products necessitates reliable methods for rapid, on-site authentication. This study aims to establish a rapid, green, and on-site method to identify the authenticity of DOL. A comprehensive analysis was conducted on 10 batches of DOL samples sourced from diverse locations, utilizing a miniature mass spectrometer (mini MS) equipped with a paper capillary spray (PCS) technique. Multivariate statistical approaches were employed to classify the samples and pinpoint chemical markers indicative of authenticity. Subsequent MS-guided separation and thin-layer chromatography (TLC) verified the markers' validity and assessed the greenness profile by Analytical Eco-scale (AES), Green Analytical Procedure Index (GAPI), and Analytical GREEnness (AGREE). A total of 10 batches of DOL samples detected by PCS-mini MS were classified into authentic and counterfeit, by unsupervised cluster analysis. Sativanone (m/z 301.1, VIP=6.0, p=0.000001) and 3′-O-methylviolanone (m/z 331.1, VIP=3.2, p=0.000382) were regarded as the chemical markers for the rapid identification of DOL. The results of the TLC method were consistent with this method, and the new method is greener. The application of mini MS for on-site authentication of DOL via specific chemical markers offers significant advantages, including operational simplicity, high efficiency, greenness, and accuracy. The deployment of this strategy promises to facilitate the effective regulation of DOL, ensuring authenticity and quality.

Positional differences in the micro- and ultra-structural variations of ray parenchyma cells during the transformation from sapwood to heartwood.

Ray parenchyma cells are involved in the initiation of heartwood formation. The position within a ray influences the timing of ray parenchyma cell differentiation and function; however, there is little information concerning the positional influence on the cellular changes of ray parenchyma cells from sapwood and heartwood. In this study, radial variations in morphology, size, and ultrastructure of ray parenchyma cells were studied by combined transmission electron microscopy and optical microscopy. Results showed that cellular traits of ray parenchyma cells in Populus tomentosa were all affected by both radial position in the secondary xylem and position within a ray. Specifically, radial variations in cellular traits were more evident in isolation cells, which were not adjacent to vessel elements. Both cell length and cell width/length ratio of isolation cells were bigger than contact cells, which contacted adjacent vessel elements via pits. Moreover, the secondary wall thickening and lignification of contact cells developed in the current-year xylem, much earlier than isolation cells. Secondary walls in contact cells were in a polylamellate structure with a protective layer on the inner side. No alteration in the ultrastructure of contact cells occurred in the sapwood-heartwood transition zone, except that most contact cells died. By contrast, in the transition zone, isolation cells still lived. A thin secondary wall began to deposit on the thick primary wall of isolation cells, with two isotropic layers on the inner side of the primary wall and secondary wall respectively being characteristic. Meanwhile, starch grains in isolation cells were depleted, and dark polyphenolic droplets lost their spherical shape and flowed together. Furthermore, the intercellular spaces of isolation cells became densified in the transition zone. Overall, cellular changes suggested that the positional information of ray parenchyma cells appeared to be an important factor in the transformation from sapwood to heartwood. Unlike contact cells, isolation cells were more elongated, specialized in radial transport, had a delayed formation of secondary walls, and were involved in the synthesis of heartwood substances. Our result promotes the elucidation of the involvement of xylem rays in heartwood formation.

Functional characterization of sesquiterpene synthase in Mongolian medicine Syringa oblata in heartwood formation

Lilac (Syringa oblata) is a well-known horticultural plant, and its aromatic heartwood is widely utilized in Traditional Mongolian Medicine for treating angina. However, limited research on the dynamic changes and mechanisms of aromatic substance formation during heartwood development hinders the analysis and utilization of its medicinal components. In this study, volatile metabolome analysis revealed that sesquiterpenes are the primary metabolites responsible for the aroma in heartwood, with cadinane and eremophilane types being the most prevalent. Among the identified sesquiterpene synthases, SoSTPS1-5 exhibited significantly increased expression in heartwood formation and was selected for further investigation. Molecular docking simulations predicted multiple amino acid binding sites and confirmed its ability to catalyze the formation of eremophilane, copaene, cadinane, germacrane, and elemane-type sesquiterpenes from FPP (farnesyl pyrophosphate). Co-expression and promoter analysis suggested a transcriptional regulatory network primarily involving WRKY transcription factors. Additionally, aiotic and biotic stress inducers, such as Ag+, Fusarium oxysporum, and especially MeJA, were found to activate the expression of SoSTPS1-5 and promote sesquiterpene accumulation. This study provides insights into the basis of medicinal substance formation and the potential mechanisms of sesquiterpene accumulation in lilac heartwood, laying a foundation for future research on the biosynthesis and utilization of its medicinal components.

Identification of Transcription Factors of Santalene Synthase Gene Promoters and SaSSY Cis-Elements through Yeast One-Hybrid Screening in Santalum album L.

The main components of sandalwood heartwood essential oil are terpenoids, approximately 80% of which are α-santalol and β-santalol. In the synthesis of the main secondary metabolites of sandalwood heartwood, the key gene, santalene synthase (SaSSY), can produce α-santalene and β-santalene by catalyzed (E, E)-FPP. Furthermore, santalene is catalyzed by the cytochrome monooxygenase SaCYP736A167 to form sandalwood essential oil, which then produces a fragrance. However, the upstream regulatory mechanism of the key gene santalene synthase remains unclear. In this study, SaSSY (Sal3G10690) promoter transcription factors and SaSSY cis-elements were screened. The results showed that the titer of the sandalwood cDNA library was 1.75 × 107 CFU/mL, 80% of the inserted fragments identified by PCR were over 750 bp in length, and the positivity rate of the library was greater than 90%. The promoter region of the SaSSY gene was shown to have the structural basis for potential regulatory factor binding. After sequencing and bioinformatics analysis, we successfully obtained 51 positive clones and identified four potential SaSSY transcriptional regulators. Sal6G03620 was annotated as the transcription factor MYB36-like, and Sal8G07920 was annotated as the small heat shock protein HSP20 in sandalwood. Sal1G00910 was annotated as a hypothetical protein of sandalwood. Sal4G10880 was annotated as a homeobox-leucine zipper protein (ATHB-15) in sandalwood. In this study, a cDNA library of sandalwood was successfully constructed using a yeast one-hybrid technique, and the transcription factors that might interact with SaSSY gene promoters were screened. This study provides a foundation for exploring the molecular regulatory mechanism involved in the formation of sandalwood heartwood.

Morphological, Physiological, Biochemical and Metabolite Analyses of Parenchyma Cells Reveal Heartwood Formation Mechanism of Schima superba

A sapwood tree is a species in which the sapwood does not differ significantly from the heartwood and cannot be classified by shades of color. It is generally accepted that heartwood has a higher economic value than sapwood, but most of the studies related to heartwood formation have focused on heartwood trees, with less research on sapwood trees. In this paper, we take the sapwood tree Schima superba as the research object and analyze the physiological and biochemical changes in the process of heartwood formation by studying the anatomical structure of parenchyma cells, and then further explore the main categories of metabolites and compositional changes. The results showed that during heartwood formation, the parenchyma cells become inactive and the nucleus disappears, while at the same time, the storage substance starch is gradually degraded under the action of enzymes and transformed into secondary metabolites, which include terpenoids, phenols and alkaloids. The accumulation of white and colorless compounds in large quantities in the heartwood, which has some effect on the heartwood color, is an important reason why the heartwood in Schima superba shows normal formation but no difference in color from the sapwood. This study fills a gap in the mechanism of heartwood formation in sapwood trees.

Physiological, Biochemical, and Molecular Analyses Reveal Dark Heartwood Formation Mechanism in Acacia melanoxylon.

Acacia melanoxylon is highly valued for its commercial applications, with the heartwood exhibiting a range of colors from dark to light among its various clones. The underlying mechanisms contributing to this color variation, however, have not been fully elucidated. In an effort to understand the factors that influence the development of dark heartwood, a comparative analysis was conducted on the microstructure, substance composition, differential gene expression, and metabolite profiles in the sapwood (SW), transition zone (TZ), and heartwood (HW) of two distinct clones, SR14 and SR25. A microscopic examination revealed that heartwood color variations are associated with an increased substance content within the ray parenchyma cells. A substance analysis indicated that the levels of starches, sugars, and lignin were more abundant in SP compared to HW, while the concentrations of phenols, flavonoids, and terpenoids were found to be higher in HW than in SP. Notably, the dark heartwood of the SR25 clone exhibited greater quantities of phenols and flavonoids compared to the SR14 clone, suggesting that these compounds are pivotal to the color distinction of the heartwood. An integrated analysis of transcriptome and metabolomics data uncovered a significant accumulation of sinapyl alcohol, sinapoyl aldehyde, hesperetin, 2', 3, 4, 4', 6'-peptahydroxychalcone 4'-O-glucoside, homoeriodictyol, and (2S)-liquiritigenin in the heartwood of SR25, which correlates with the up-regulated expression of CCRs (evm.TU.Chr3.1751, evm.TU.Chr4.654_667, evm.TU.Chr4.675, evm.TU.Chr4.699, and evm.TU.Chr4.704), COMTs (evm.TU.Chr13.3082, evm.TU.Chr13.3086, and evm.TU.Chr7.1411), CADs (evm.TU.Chr10.2175, evm.TU.Chr1.3453, and evm.TU.Chr8.1600), and HCTs (evm.TU.Chr4.1122, evm.TU.Chr4.1123, evm.TU.Chr8.1758, and evm.TU.Chr9.2960) in the TZ of A. melanoxylon. Furthermore, a marked differential expression of transcription factors (TFs), including MYBs, AP2/ERFs, bHLHs, bZIPs, C2H2s, and WRKYs, were observed to be closely linked to the phenols and flavonoids metabolites, highlighting the potential role of multiple TFs in regulating the biosynthesis of these metabolites and, consequently, influencing the color variation in the heartwood. This study facilitates molecular breeding for the accumulation of metabolites influencing the heartwood color in A. melanoxylon, and offers new insights into the molecular mechanisms underlying heartwood formation in woody plants.

Genome-wide characterization of post-transcriptional processes related to wood formation in Dalbergia odorifera

BackgroundAlternative polyadenylation (APA), alternative splicing (AS), and long non-coding RNAs (lncRNAs) play regulatory roles in post-transcriptional processes in plants. However, little is known about their involvement in xylem development in Dalbergia odorifera, a valuable rosewood species with medicinal and commercial significance. We addressed this by conducting Isoform Sequencing (Iso-Seq) using PacBio’s SMRT technology and combined it with RNA-seq analysis (RNA sequencing on Illumina platform) after collecting xylem samples from the transition zone and the sapwood of D. odorifera.ResultsWe identified 14,938 full-length transcripts, including 9,830 novel isoforms, which has updated the D. odorifera genome annotation. Our analysis has revealed that 4,164 genes undergo APA, whereas 3,084 genes encounter AS. We have also annotated 118 lncRNAs. Furthermore, RNA-seq analysis identified 170 differential alternative splicing (DAS) events, 344 genes with differential APA site usage (DE-APA), and 6 differentially expressed lncRNAs in the transition zone when compared to the sapwood. AS, APA, and lncRNAs are differentially regulated during xylem development. Differentially expressed APA genes were enriched for terpenoid and flavonoid metabolism, indicating their role in the heartwood formation. Additionally, DE-APA genes were associated with cell wall biosynthesis and terpenoid metabolism, implying an APA’s role in wood formation. A DAS gene (involved in chalcone accumulation) with a significantly greater inclusion of the last exon in the transition zone than in the sapwood was identified. We also found that differentially expressed lncRNAs targeted the genes related to terpene synthesis.ConclusionsThis study enhances our understanding of the molecular regulatory mechanisms underlying wood formation in D. odorifera, and provides valuable genetic resources and insights for its molecular-assisted breeding.

Water, starch, and nuclear behavior in ray parenchyma during heartwood formation of Catalpa bungei ‘Jinsi’

Catalpa bungei ‘Jinsi’, a cultivar of C. bungei C. A. Mey., is valued for its heartwood with good overall mechanical properties, naturally durable and golden-yellow color. Little is known about heartwood formation in C. bungei ‘Jinsi’ trees. The behavior of starch, water, and nuclei was studied in the xylem tissue of C. bungei ‘Jinsi’ concerning aging in ray parenchyma cells. Blocks containing heartwood, golden zone, transition zone, and sapwood were collected from the stems of six C. bungei ‘Jinsi’ trees. The moisture content of the blocks was measured by oven drying. Changes in starch and nuclei in ray parenchyma were investigated in radial profiles from sapwood to heartwood blocks using microscopy and various staining techniques. The nuclear size and starch content gradually decreased to heartwood. While the horizontal distribution of moisture content of C. bungei ‘Jinsi’ was very varied, with the heartwood and golden zone being lower than sapwood but slightly higher than the transition zone. Starch grains were rare, but nuclei were still present in some ray parenchyma cells in the heartwood and golden zone. The nuclei showed irregular shape and elongation before disintegration. These results suggest that the most apparent change occurs in the transition zone, the critical location involved in forming C. bungei ‘Jinsi’ heartwood. Water and starch appear to be actively engaged in heartwood formation. The loss of function of ray parenchyma cells results from heartwood formation.

Effects of ethephon on heartwood formation and related physiological indices of Dalbergia odorifera T. Chen

IntroductionDalbergia odorifera T. Chen, known as fragrant rosewood, is a rare and endangered tree species. Studies have shown that plant growth regulators can effectively promote heartwood formation. This study aimed to investigate the effects of ethephon (ETH) on heartwood formation and the influence of ethephon and hydrogen peroxide (H2O2) on the physiological characteristics in D. odorifera.MethodsD. odorifera branches underwent treatment with 2.5% plant growth regulators, including ETH, jasmonic acid (JA), salicylic acid (SA), abscisic acid (ABA), H2O2, and inhibitors such as ascorbic acid (AsA) to inhibit H2O2 synthesis, and (S) -trans 2-amino-4 - (2-aminoethoxy) -3-butene (AVG) to inhibit ethylene synthesis. After a 14-day period, we conducted an analysis to evaluate the impact of these plant growth regulators on elongation distance, vessel occlusion percentage, and trans-nerol content. Additionally, the effects of ETH and H2O2 on endogenous plant hormones, H2O2 content, soluble protein content, and enzyme activity were investigated within 0-48 h of treatment.ResultsAfter treatment with ETH for 14 days, the extension distance of the heartwood material was 15 cm, while the trans-nerolol content was 15 times that of the ABA group. ETH and H2O2 promoted endogenous ethylene synthesis; Ethylene content peaked at 6 and 18 h. The peak ethylene content in the ETH group was 68.07%, 12.89%, and 20.87% higher than the initial value of the H2O2 group and ddH2O group, respectively, and 29.64% higher than that in the AVG group. The soluble protein content and activity of related enzymes were significantly increased following ETH treatment.DiscussionETH exhibited the most impact on heartwood formation while not hindering tree growth. This treatment effectively triggered the production of endogenous ethylene in plants and enhanced the activity of essential enzymes involved in heartwood formation. These findings serve as a valuable reference for future investigations into heartwood formation.

Analysis of Lipophilic Constituents Related to Heartwood Formation in Young Swietenia mahagoni (L.) Jacq Trees

Analysis of Lipophilic Constituents Related to Heartwood Formation in Young Swietenia mahagoni (L.) Jacq Trees

Cambial Age Influences PCD Gene Expression during Xylem Development and Heartwood Formation

Heartwood formation is an important ontogenetic stage in Scots pine (Pinus sylvestris L.). The amount of heartwood determines the proportion of functionally active sapwood in the total trunk biomass as well as the quality of wood. The key criterion for heartwood formation is the death of xylem ray parenchyma cells. Previously, models that described the patterns of heartwood formation, depending on the cambial age, were derived from Scots pine trees of different ages. The cambial age is the number of annual xylem layers at the core sampling site at a certain trunk height. We studied the features of the occurrence of programmed cell death (PCD) processes during the xylem differentiation and heartwood formation of 80-year-old Scots pine trees, depending on the cambial age, under the lingonberry pine forest conditions in the transition area of the northern taiga subzone and tundra. We have shown that the distance from the cambial zone to the heartwood boundary does not change significantly with stem height. As the cambial age increases, the lifespan of the formed xylem ray parenchyma cells increases and the activity of PCD genes decreases during the formation of both (1) xylem (in the outer layers of sapwood) and (2) heartwood (in the inner layers of sapwood and transition zone). We hypothesized that the decisive factor in the PCD initiation during heartwood formation is the distance of the xylem ray parenchyma cells from the cambial zone. The younger cambium forms wider annual increments, and therefore the xylem ray parenchyma cells in these parts of the trunk reach the distance from the cambial zone earlier, which is necessary for PCD initiation.

Age of heartwood initiation in trunks of young Pinus sylvestris L. trees in the taiga zone

Summary This work is part of a project investigating the heartwood formation process in Scots pine. Despite the economic and ecological importance of pine heartwood (HW), the process of its formation in many respects remains poorly understood. Scientists believe that HW formation in Scots pine begins at 9–20 years, however, systematic studies of HW initiation age in this species have not previously been conducted. Samples were collected from 105 P. sylvestris trees aged 10 to 25 years, growing in the middle and northern taiga subzones, as well as on the border of the northern taiga subzone with the tundra. Samples were taken at the trunk base according to a single technique and processed using two biochemical (peroxidase activity, pinosylvin presence) and two anatomical markers (presence of extractives on the tracheid pit membranes, nuclei disappearance) characterizing different events during HW formation. Biochemical markers showed an overestimation in the number of HW annual rings compared with HW determination based on anatomical criteria by 1–3 years, on average. Attempts to detect peroxidase activity showed a negative result in the inner sapwood annual ring, while detectable pinosylvin accumulation occurred in the transition zone (TZ). We have detected for the first time true HW (without living cells) in Scots pine samples with a cambial age (CA) of 15–17 years. The number of growth rings in TZ and HW in young trees depended on growth conditions. These results are important for understanding the mechanisms of HW formation and developing realistic models of this process, including changing climate conditions.

Changes in the physiological activity of parenchyma cells in Dalbergia odorifera xylem and its relationship with heartwood formation

BackgroundThe formation of a tree’s heartwood gives the wood properties such as natural decay resistance and aesthetic color, and often directly determines the value of wood products. Regulating the quantity and quality of heartwood is of great importance to the use of wood. However, the mechanism of heartwood formation has been poorly understood.ResultsUsing Dalbergia odorifera as the study species, the number of starch grains, the morphology of the nuclei, the changes in the content of water and secondary metabolites were observed continuously in the radial direction of the xylem. The results show that from the outer toward inner sapwood, the starch grains are abundant, the length to diameter ratio of the nuclei is decreasing, and the morphology changes from elongated elliptical and then to round. In the outer transition zone, the starch grains begin to decrease abruptly and the nuclei shrink at a slower rate, with a radial width of approximately 2 mm. In the inner transition zone, the heartwood color begins to appear, the starch grains disappear and a few nuclei with reduced fluorescence are present, with a radial width of approximately 1 mm. Heartwood formation after complete disappearance of the nuclei. The moisture content of the heartwood is higher than that of the sapwood, and the inner transition zone is where the content rises. The secondary metabolites of the heartwood begin to accumulate in large quantities in the inner transition zone.ConclusionBased on the physiological changes of parenchyma cells in the xylem, the radial width of the transition zone of Dalbergia odorifera is clearly defined as approximately 3 mm. Both the water and secondary metabolite abrupt changes occur at the final stage of programmed cell death, and neither is a direct cause of programmed cell death in parenchyma cells.

Savinin Triggers Programmed Cell Death of Ray Parenchyma Cells in Heartwood Formation of Taiwania cryptomerioides Hayata.

The purpose of this study was to investigate the relationship between lignan biosynthesis and programmed cell death (PCD) of ray parenchyma cells during the heartwood formation of Taiwania (Taiwania cryptomerioides Hayata). Since the PCD of ray parenchyma cells and the synthesis of lignans are the two main processes involved in the formation of heartwood, both of which need to be completed through gene regulation. Based on the results of genomics and bioinformatics analysis, that the PCD of tracheids are induced by genotoxic, and the PCD of ray parenchyma cells is induced by biological factors, such as fungi, bacteria, and viruses, which could induce oxidative stress. According to the results of time-of-flight secondary ion mass spectrometry (ToF-SIMS) analysis, lignans are produced in ray parenchyma cells, and the accumulation of savinin and its downstream lignans might be the cause of PCD in ray parenchyma cells. An in vitro experiment further confirmed that the accumulation of savinin could cause protoplasts of Taiwania's xylem to produce taiwanin A, which is the marker of heartwood formation in Taiwania. Resulting in an increase in reactive oxygen species (ROS) content, which could induce oxidative stress in ray parenchyma cells and potentially lead to PCD. Based on these findings, we conclude that accumulation of savinin could be induced PCD of ray parenchyma cells in heartwood formation in Taiwania.

Function of the R2R3-MYB Transcription Factors in Dalbergia odorifera and Their Relationship with Heartwood Formation.

R2R3-MYB transcription factors (TFs) form one of the most important TF families involved in regulating various physiological functions in plants. The heartwood of Dalbergia odorifera is a kind of high-grade mahogany and valuable herbal medicine with wide application. However, the role of R2R3-MYB genes in the growth and development of D. odorifera, especially their relevance to heartwood formation, has not been revealed. A total of 126 R2R3-MYBs were screened from the D. odorifera genome and named DodMYB1-126 based on their location on 10 chromosomes. The collinearity results showed that purification selection was the main driving force for the evolution of the R2R3-MYB TFs family, and whole genome/fragment replication event was the main form for expanding the R2R3-MYB family, generating a divergence of gene structure and function. Comparative phylogenetic analysis classified the R2R3-MYB TFs into 33 subfamilies. S3-7,10,12-13,21 and N4-7 were extensively involved in the metabolic process; S9,13,16-19,24-25 and N1-3,8 were associated with the growth and development of D. odorifera. Based on the differential transcriptional expression levels of R2R3-MYBs in different tissues, DodMYB32, DodMYB55, and DodMYB89 were tentatively screened for involvement in the regulatory process of heartwood. Further studies have shown that the DodMYB89, localized in the nucleus, has transcriptional activation activity and is involved in regulating the biosynthesis of the secondary metabolites of heartwood by activating the promoters of the structural genes DodI2'H and DodCOMT. This study aimed to comprehensively analyze the functions of the R2R3-MYB TFs and screen for candidate genes that might be involved in heartwood formation of D. odorifera.

Earlier onset and slower heartwood investment in faster-growing trees of African tropical species.

Heartwood plays an important role in maintaining the structural integrity of trees. Although its formation has long been thought to be driven solely by internal ageing processes, more recent hypotheses suggest that heartwood formation acts as a regulator of the tree water balance by modulating the quantity of sapwood. Testing both hypotheses would shed light on the potential ecophysiological nature of heartwood formation, a very common process in trees. We measured quantities of heartwood and sapwood, xylem conduits and the width and number of growth rings on 406 stems of Pericopsis elata with ages ranging from 2 to 237 years. A subset of 17 trees with similar ages but varying growth rate were sampled in a shaded (slower-growth) site and a sun-exposed (faster-growth) site. We used regression analysis and structural equation modelling to investigate the dynamics and drivers of heartwood formation. We found a positive effect of growth rate on the probability of heartwood occurrence, suggesting an earlier heartwood onset in faster-growing stems. After this onset age, heartwood area increased with stem diameter and age. Despite the similar heartwood production per unit stem diameter increment, shaded trees produced heartwood faster than sun-exposed trees. Tree age and hydraulics showed similar direct effects on heartwood and sapwood area of sun-exposed trees, suggesting their mutual role in driving the heartwood dynamics of sun-exposed trees. However, for shaded trees, only tree hydraulics showed a direct effect, suggesting its prominent role over age in driving the heartwood dynamics in limited growing conditions. The positive relationship between growth rate and maximum stomatal conductance supported this conclusion. Heartwood area increases as the tree ages, but at a slower rate in trees where water demand is balanced by a sufficient water supply. Our findings suggest that heartwood formation is not only a structural process but also functional.

Differences in Some Physical and Chemical Properties of Beechwood with False Heartwood, Mature Wood and Sapwood

The article presents the differences in some physical and chemical properties of wood with false heartwood, mature wood, and sapwood of Fagus sylvatica L.: density of wood in the dry state, color in the color space CIE L*a*b* on the tangential surface and the planed surface at w = 10 ± 0.5%, as well as moisture and acidity of wet wood. As part of chemical analyses, the relative proportion of cellulose, hemicelluloses, lignin, and extractive substances in individual zones of beechwood in trunks with false heartwood was determined. From the carried out analyses, it follows that the biggest difference between the wood of false heartwood, mature wood, and sapwood is the color of the wood. The red-brown color of the wood with false heartwood in the color space CIE L*a*b* is described by the following coordinate values: L* = 64.9 ± 4.9; a* = 12.9 ± 1.4; b* = 19.6 ± 1.7. The most significant differences between the values of the color space are on the lightness coordinate, where the light ochre-white of mature wood shows a decrease of ∆L* = −14.0 compared with the color of false heartwood, and the white—pale grey color of sapwood shows a decrease of ∆L* = −17.5. The density of dry beechwood with false heartwood is higher by ∆ρ0 = 4.7% than the density of mature wood, and the density of sapwood is ∆ρ0 = 12.3% lower than the density of wood with false heartwood. The exact opposite applies to the acidity of wet beechwood. The results of wet wood acidity measurements also point to certain differences. While the acidity of the wet wood of false heartwood is pH = 5.32 ± 0.13, the acidity of the sapwood is 5.1% lower. The higher acidity of beech heartwood is attributed to the presence of organic acids in polyphenols during heartwood formation. From the comparison of the representation of cellulose, hemicellulose, lignin, and extractive substances, it follows that the relative content of lignin and hemicelluloses is higher in false heartwood than in mature wood and sapwood. On the contrary, the content of holocellulose and cellulose is highest in sapwood. The presented divisions in the physical and chemical properties of beechwood with false heartwood do not limit the use of beechwood in industrial applications, except for a change in color; the definition of color boundaries in the color space CIE L*a*b* creates space for sorting beechwood according to color and can be used to increase the color variety of compositions of construction-carpentry products.

Fossil evidence of tylosis formation in Late Devonian plants.

Tyloses are swellings of parenchyma cells into adjacent water-conducting cells that develop in vascular plants as part of heartwood formation or specifically in response to embolism and pathogen infection. Here we document tyloses in Late Devonian (approximately 360 Myr ago) Callixylon wood. This discovery suggests that some of the earliest woody trees were already capable of protecting their vascular system by occluding individual conducting cells.

Cross-sectioning to the core of conifers: pith anatomy of living Araucariaceae and Podocarpaceae, with comparisons to fossil pith

Summary Pith in woody species fulfills essential roles, from functioning as the first vascular tissue in shoots, to serving as starch storage and facilitating heartwood formation. While the spongy cells of pith may die and be reabsorbed at maturity by some species, the pith persists throughout the lifespan of conifer trees. Pith features and functions of extant conifers have been documented in contemporary studies, and pith anatomy has been described for extinct progymnosperms and coniferous ancestors through fossils. However, up to now, few studies have described the wood anatomy of pith in living conifers and covered only 24 species in four families. Here we describe the pith of 7 genera and 16 species from the previously unstudied conifer families of Araucariaceae and Podocarpaceae, based on stained and unstained cross-sections. Comparisons between pith sections of the same tree in successive years yielded insights into maturation of the conifer pith. Conservative pith characteristics were identified among genera and families. Araucariaceae pith is dissimilar on a familial level, but the genus Araucaria is unified by pith shape and heterocellularity. In contrast, all Podocarpaceae piths develop secondary cracks, and most species have irregularly shaped piths. Beyond our study of similarities and differences of pith in Araucariaceae and Podocarpaceae, a look at pith patterns in the paleobotanical record and further examples in living conifers could increase the understanding of conserved characteristics and pith evolution.

Repellent properties against four Ascomycota species and Reticulitermes flavipes of acetonic extractives from Cedrus atlantica sapwood to inner heartwood fractions

Cedrus atlantica is a tree species present in the south of France which, in the context of climate change, could become a conservation priority in the coming years. This tree species is also of considerable ecological and socio-economic interest in the Mediterranean Basin area, where it is mainly recognized for its durable timber, and also for the potentially interesting chemical properties of its essential oil. Studies of its heartwood formation and the properties of its extractives are therefore of interest, although very few have been conducted so far. The radial distribution of water/acetone extractives within the Atlas cedar tree (bark, sapwood, transition wood, outer heartwood and inner heartwood) selected for this study was screened at different tree height levels. High-performance liquid chromatography (HPLC) analyses were performed, especially to characterize flavonoid compounds in these extractive fractions. The radial variation of the extractive composition obtained highlights the phenomenon of heartwood formation. Assumptions were put forward as to the metabolic pathways involved in the heartwood formation process of cedar wood, based in particular on the occurrence and radial evolution of (-)-catechin, (+)-taxifolin and flavan compounds. The fungicidal and termite-repellent activities of the extracts were then tested. The water/acetone extractives from the Cedrus atlantica individual studied showed strong termite repellent activity and moderate antifungal activity against crop and fruit pathogens. Even though the sampling in this study was limited to a single tree, the results point to a potential for commercial use of Atlas cedar extractives as wood preservatives and/or as biocontrol products against pathogens of woody agricultural crops. Additional tests and chemical analyses will be carried out to confirm these interesting preliminary results.