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Drought has been found to affect the size and color of precious heartwood of Dalbergia odorifera, but the mechanism remains unclear. For this purpose, we performed the measurement of heartwood size, color and flavonoid content and composition in a 15-year-old mixed plantation of D. odorifera and Santalum album that had been subjected to two levels of rainfall exclusion and control treatments for 7 years, and carbon isotope labeling and anatomical observation in 2-year-old potted D. odorifera seedlings exposed to two levels of drought and control treatments. The field experiment showed that drought had significant effects on heartwood size and color of D. odorifera. More starch was depleted in the transition zone (TZ) in drought than in control. Drought significantly decreased the values of color parameters and increased the contents of total flavonoids, glycitein, fisetin, chrysin and claussequinone, and total flavonoids, glycitein, fisetin, chrysin and claussequinone were significantly negatively correlated with L* and b*. The pot experiment showed that during longitudinal transport of nonstructural carbohydrate (NSC), the dilution factor of 13C abundance in the inner bark sap in severe drought (SD) was twice as much as that in control. The inner bark thickness and transverse area of sieve tubes in SD were significantly lower than those in control. Our findings further confirm that drought promotes the heartwood formation of D. odorifera, and discuss interspecific variations in the response of heartwood formation to drought. Drought enhances the exchange transport of NSC between phloem and xylem by reducing the transverse area of sieve tubes, thus causing more NSC to be transported into xylem, and drought also promotes the depletion of starch in the TZ to produce more heartwood. Drought darkens the heartwood color by increasing the contents of total flavonoids, glycitein, fisetin, chrysin and claussequinone in heartwood. To our knowledge, this is the first study addressing the physiological and biochemical mechanism of drought regulating heartwood formation., (© The Author(s) 2024. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permission@oup.com.)

Background: Grape (Vitis vinifera) crops encounter significant challenges in overcoming bud endodormancy in warm winter areas worldwide. Research on the mechanisms governing bud dormancy release has focused primarily on stress regulation; however, cell wall regulation of bud meristem regrowth mechanism during the dormancy release remains obscure., Results: In this study, transmission electron microscopy revealed significant changes in the grape bud cell wall following hydrogen cyanamide (HC) treatment, accompanied by an increase in β-1,3-glucanase activity. We then investigated the potential contribution of β-1,3-glucanases (GLUs) to the regulation of cell wall remodeling. Forty-eight VvGLUs distributed in clades α, β, and γ were identified and nominated based on the genome data of V. vinifera. Three γ-clade VvGLUs (VvGLU1, VvGLU16, and VvGLU32) were upregulated by dormancy-releasing stimuli, including HC, sodium azide (AZ), ethylene and hypoxia. Among these, VvGLU1 presented increased gene transcription and protein expression in response to HC and ethylene treatment. The VvGLU1 promoter positively responded to ethylene, and its activity could be activated by VvERF57. Using both immunogold labeling and GFP fusion protein analysis, we observed that VvGLU1 localized in the endoplasmic reticulum, accumulated in the vacuole, and was secreted into the cell wall during HC-triggered dormancy release., Conclusions: Based on these findings, we propose that ethylene-regulated VvGLU1 plays a pivotal role in cell wall remodeling, thereby facilitating the regrowth of the bud meristem., Competing Interests: Declarations. Ethics approval and consent to participate: Not applicable. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests., (© 2025. The Author(s).)

In recent years, some new "Qi-Nan" clones of Aquilaria sinensis with the characteristics of easy induction and high-quality agarwood have been obtained, through the cultivation and propagation of grafted seedlings. These clones are used for the intensive production of high-quality agarwood. The speed of resin formation and yield are crucial for the development of the agarwood industry. The differences in yield and chemical composition among different Qi-Nan clones and induction times are worth investigating. While the chemical composition differences between Qi-Nan and ordinary A. sinensis have been extensively studied, the effects of induction time coupled with different Qi-Nan clones on the chemical composition of Qi-Nan agarwood remain insufficiently explored. This study compared the changes in the chemical composition of four "Qi-Nan" clones of A. sinensis after 6, 12, and 24 months of induction through GC-QTOF-MS, the chemical composition and structure types of the four "Qi-Nan" clones were mainly 2-(2-phenylethyl)chromone derivatives (PECs) and Sesquiterpenoids (SESs), with the prolongation of induction time, the content of SESs increased, while the content of PECs decreased. Both the differences among clones and the induction time of "Qi-Nan" agarwood influence its chemical composition, which in turn affects the quality of the agarwood. Among these factors, induction time has a greater impact on the production of PECs in agarwood. The prolongation of induction significantly enhanced the yield of "Qi-Nan" agarwood and exhibited an inducing effect on the production of 2-(2-phenylethyl) chromone and 2-(2-4 phenylethyl)chromone. Compared with the agarwood obtained after 6 and 12 months of induction, the agarwood of "Qi-Nan" after 24 months of induction exhibited superior quality. The induction time for high-quality agarwood from the XGY clone was shorter (12 months) compared to the RH, YYZ, and AS clones (24 months). The study underscores that optimizing induction time and selecting suitable "Qi-Nan" clones can significantly enhance agarwood yield, quality, and production efficiency.

Fertilization can improve soil nutrition and increase the yield of Sapindus mukorossi , but the response of soil microbial communities to fertilization treatments and their correlation with soil nutrition and Sapindus mukorossi yield are unclear. In order to investigate the characteristics of soil physicochemical qualities and the bacterial community, we carried out a field experiment comparing various quantities of nitrogen (N), phosphorus (P), and potassium (K) fertilizers to the unfertilized control treatments and the yield of Sapindus mukorossi in raw material forests in response to different applications of fertilizers and to try to clarify the interrelation among the three. Results showed that (1) there are significant differences in the effects of different fertilization treatments on the soil properties of Sapindus mukorossi raw material forests. The increase in the application rates of nitrogen or phosphorus fertilizers significantly reduced the soil pH value. (2) Compared with control, the α-diversity of bacterial communities was significantly lower in N 3 P 2 K 2 and N 1 P 1 K 2 treatments. Among the dominant groups of soil bacteria at the phylum level, the relative abundance of Chloroflexi showed an increase and then a decrease trend with the increase in N application. The relative abundance of Firmicutes , Bacteroidota , and Fusobacteriota was positively correlated with the application of P and K fertilizers, while the relative abundance of Acidobacteriota and Verrucomicrobiota decreased with the increase in P and K fertilizers. (3) The N 2 P 2 K 2 treatment produced the highest sapindus yield (1464.58 kg/ha), which increased by 258.67% above the control. (4) Redundancy analysis (RDA) showed that the primary determinants of bacterial community structure were soil pH, total K, and effective P concentration. (5) Structural equation modeling (SEM) showed that soil nutrient content was the main direct factor driving the yield of Sapindus mukorossi , whereas the bacterial community attributes (e.g., diversity and structure) had minor effects on the yield. In summary, the rational use of formulated fertilization can change the bacterial community structure, improve the bacterial diversity, and increase the soil nutrient content, with the latter exerting a significant effect on the improvement of the yield of Sapindus mukorossi .

Phallus echinovolvatus is a well-known edible and medicinal fungus with significant economic value. However, the available whole-genome information is lacking for this species. The chromosome-scale reference genome (Monop) and two haploid genomes (Hap1 and Hap2) of P. echinovolvatus , each assembled into 11 pseudochromosomes, were constructed using Illumina, PacBio-HiFi long-read sequencing, and Hi-C technology. The Monop had a size of 36.54 Mb, with 10,251 predicted protein-coding genes and including 433 carbohydrate-active enzyme genes, 385 cytochrome P450 enzyme genes, and 42 gene clusters related to secondary metabolite synthesis. Phylogenetic and collinearity analysis revealed a close evolutionary relationship between P. echinovolvatus and Clathrus columnatus in the core Phallales clade. Hap1 and Hap2 had sizes of 35.46 Mb and 36.11 Mb, respectively. Collinear relationships were not observed for 15.38% of the genes in the two haplotypes. Hap1 had 256 unique genes, and Hap2 had 370 unique genes. Our analysis of the P. echinovolvatus genome provides insights into the genetic basis of the mechanisms underlying the metabolic effects of bioactive substances and will aid ongoing breeding efforts and studies of genetic mechanisms.

Heartwood, serving as the central constituent of the xylem, plays a crucial role in the growth, development, and resilience of trees. The process of heartwood formation constitutes a complex biological phenomenon influenced by various factors. A thorough examination of the mechanisms underpinning heartwood formation not only enhances our understanding of the growth and developmental paradigms regulating trees but also provides essential theoretical support and practical insights for the timber industry, forestry management, and ecological conservation. This paper offers an overview of the foundational processes involved in heartwood formation in plants. Furthermore, it presents a comprehensive review of the latest research advancements in this domain, covering five key aspects: metabolism, hormonal regulation, transcriptional regulation, cell biology, and environmental influences. This review serves as a valuable basis for future research endeavors in related academic fields.

Background: Calmodulin-binding transcription activator (CAMTA) proteins play significant roles in signal transduction, growth and development, as well as abiotic stress responses, in plants. Understanding their involvement in the low-temperature stress response of teak is vital for revealing cold resistance mechanisms., Results: Through bioinformatics analysis, the CAMTA gene family in teak was examined, and six CAMTA genes were identified in teak. The encoded proteins were predicted to be located in the nucleus and exhibited hydrophilic properties, with molecular weights ranging from 103.4 to 123.3 kDa and isoelectric points ranging from 5.49 to 7.55. On the basis of protein sequence homology, the CAMTA family could be divided into three subgroups. Domain and 3D structure analyses demonstrated that all the TgCAMTA proteins contained the typical CAMTA domain with the CaMBD binding domain, which was exposed on the surface. Expression analysis of different tissues revealed the expression of TgCAMTA genes in teak roots, stems, leaves, flowers, fruits, and branches. Furthermore, the promoter region contained various cis-acting elements related to light, hormone, and abiotic stress responses. After low-temperature stress treatment, different expression patterns of TgCAMTAs were observed in teak roots, stems, and leaves, with TgCAMTA1 showing the highest expression level in leaves compared with stems. Transgenic lines carrying the TgCAMTA1/3 promoter::GUS construct cold stress induction of TgCAMTA1/3 genes revealed the presence of multiple low-temperature responsive cis-acting elements in the TgCAMTA1/3 promoter region. Subcellular localization analysis indicated that these genes were functional predominantly in the nucleus. Compared with wild-type Arabidopsis, TgCAMTA1/3-overexpressing Arabidopsis presented increased tolerance to freezing stress, with increased expression of AtCOR genes. Moreover, under low-temperature conditions, TgCAMTA3-overexpressing Arabidopsis presented significantly elevated expression levels of genes related to the CBF signaling pathway, including AtCBF1/2/3., Conclusions: Our findings add significantly to the existing knowledge regarding cold stress tolerance and help elucidate cold response mechanisms in teak., Competing Interests: Declarations. Ethics approval and consent to participate: Not applicable. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Microorganisms, the major decomposers of plant residues, are crucial for soil nutrient cycling. Living grass mulching effectively alters microbial community structure and promotes nutrient cycling. However, its consistency with mulching ages and growth periods remains unclear. Therefore, this study aims to clarify the dynamic characteristics of microbial communities and enzyme activities across different mulching ages. In this study, high-throughput sequencing technology was used to investigate bacterial and fungal community evolution in three mulching treatments with Vicia villosa for 8 years (VV_8), 4 years (VV_4), and clean tillage in a citrus orchard. This study covered three growth periods (citrus-grass: spring sprouting to budding period [SSBP], fruit swelling to withering period [FSWP], and fruit maturity to seeding period [FMSP]). The results showed that VV_4 and VV_8 treatments increased bacterial and fungal alpha diversity as well as the activities of nitrogen (N), carbon (C), and phosphorus cycling enzymes. C-cycling enzyme activity was the primary key factor driving changes in microbial diversity across growth periods. Under leguminous green mulching, bacteria alpha diversity increased the most during FSWP, while fungi increased the most during FMSP. Additionally, the relative abundance of Ascomycota and Basidiomycota significantly increased during the FSWP and FMSP, reaching 63.65-73.80 % and 79.73-84.51 %, respectively. With increasing mulching ages, the structural stability and synergistic effects of microorganisms were correspondingly enhanced. Furthermore, available nutrients determined microbial community evolution, with N availability being a key factor influencing microbial diversity, especially fungal diversity. In conclusion, as mulching ages increase, improved nutrient availability gradually enhances microbial diversity, synergistic interactions, and nutrient cycling functions, with copiotrophic taxa occupying a key position in the microbial network. FSWP is a critical turning point for enhancing microbial activity and C-cycling function. This study offers theoretical support for developing microbial regulation strategies to improve soil quality in orchard management practices., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Patchy global data on belowground litter decomposition dynamics limit our capacity to discern the drivers of carbon preservation and storage across inland and coastal wetlands. We performed a global, multiyear study in over 180 wetlands across 28 countries and 8 macroclimates using standardized litter as measures of "recalcitrant" (rooibos tea) and "labile" (green tea) organic matter (OM) decomposition. Freshwater wetlands and tidal marshes had the highest tea mass remaining, indicating a greater potential for carbon preservation in these ecosystems. Recalcitrant OM decomposition increased with elevated temperatures throughout the decay period, e.g., increase from 10 to 20 °C corresponded to a 1.46-fold increase in the recalcitrant OM decay rate constant. The effect of elevated temperature on labile OM breakdown was ecosystem-dependent, with tidally influenced wetlands showing limited effects of temperature compared with freshwater wetlands. Based on climatic projections, by 2050 wetland decay constants will increase by 1.8% for labile and 3.1% for recalcitrant OM. Our study highlights the potential for reduction in belowground OM in coastal and inland wetlands under increased warming, but the extent and direction of this effect at a large scale is dependent on ecosystem and OM characteristics. Understanding local versus global drivers is necessary to resolve ecosystem influences on carbon preservation in wetlands.

In theory, there is a trade-off between hydraulic efficiency and safety. However, the strength and direction of this trade-off at the leaf level are not consistent across studies, and habitat climate may impact this trade-off. We compiled a leaf hydraulic efficiency and safety dataset for 362 species from 81 sites world-wide, with 280 paired observations of both traits, and tested whether climate was associated with departure from the proposed trade-off. The leaf hydraulic efficiency-safety trade-off was weak (R 2  = 0.144) at the global scale. Mean annual precipitation and solar radiation (SR) modified the trade-off. Species from dry and high SR habitats (e.g. desert and tropical savanna) were generally located above the trade-off line, indicating that these species tended to have higher leaf hydraulic safety and efficiency than species from wet habitats with low SR (e.g. subtropical monsoon forest and montane rainforest), which were located below the trade-off line. Leaves with high vein density, dry leaf mass per area, and osmotic regulation enhanced safety without compromising hydraulic efficiency. Variation in the hydraulic efficiency-safety trade-off at the leaf level likely facilitates plant survival in specific habitats and allows for a more nuanced view of leaf hydraulic adaption strategies at the global scale., (© 2024 The Author(s). New Phytologist © 2024 New Phytologist Foundation.)

An inductive combination of plant growth regulators, inorganic salts, and fungi is essential for the formation of aromatic components in the xylem of Aquilaria sinensis . However, the dynamics of xylem physiology and the relationships between physiological properties and aromatic components after artificial induction remain unclear. In this study, the changes in physiological properties of A . sinensis xylem during induction were determined and analyzed under four induction treatments and a control group. The defense hormone contents of jasmonic acid, salicylic acid, aminocyclopropane-1-carboxylic acid, and abscisic acid obtained from the four induction treatments increased significantly. However, the concentrations of gibberellin and indoleacetic acid were decreased compared to the control group. An initially upward and then downward trend was observed in the main antioxidant enzyme activities. Additionally, malonaldehyde content decreased obviously, while proline content tended to increase and then decrease as induction continued. The total and soluble sugar content was evidently reduced after treatment, and the soluble sugar content recovered more rapidly with time. Thirty-three aromatic components were identified in all treatments, and the primary aromatic components were terpenes, aromatics and chromones, the relative contents of which varied among treatments. These results provide new insights for optimization and innovation of agarwood induction techniques by exploring the formation of aromatics in the xylem of A. sinensis and its physiological responses following induction with exogenous substances (ethephon, NaCl, CaCl 2 and fungal mixed solution)., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Pang, Li, Zhang, Tian, Deng, Zhang, Liu, Yang and Zhou.)

Glyphosate pollution and greenhouse gas emissions are major problem in achieving sustainable soil management. It is necessary to develop effective strategies to simultaneously reduce herbicide residues and nitrous oxide (N 2 O) emissions in soil. This study aimed to: (1) quantitative analyze the effects of nitrogen (N) cycle inhibitors (nitrification inhibitors 3,4 dimethylpyrazole phosphate (DMPP) and dicyandiamide (DCD) and urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT)) on glyphosate degradation and reduction of N 2 O under different soil moistures; (2) identify the functional microbes and genes associated with glyphosate degradation and N 2 O emissions; and (3) decipher the main mechanisms of N cycle inhibitors affecting glyphosate degradation at different soil water contents. Compared to the control, the application of DMPP, DCD and NBPT reduced glyphosate residues in soil by 33.0 %, 60.3 % and 35.7 %, respectively, under 90 % water holding capacity (WHC). The application of DCD stimulated Acidobacteria and the phnX gene to degrade soil glyphosate. Further, soil glyphosate residues were significantly and negatively related to soil N 2 O emissions at both 60 % and 90 % WHC. Compared to the control, NBPT application decreased cumulative N 2 O emissions by 91.4 % at 90 % WHC by decreasing soil nitrate N (NO 3 -N) and inhibiting amoC and narG genes at 90 %. The application of N cycle inhibitors could be a potential strategy to simultaneously reduce glyphosate residues and soil N - O emissions. Our study could provide technical support to reduce the risks of herbicide exposure and reduce greenhouse gas emissions.2 O emissions. Our study could provide technical support to reduce the risks of herbicide exposure and reduce greenhouse gas emissions., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper, (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Eucalyptus urophylla S.T. Blake, an important economic tree species, is widely cultivated as a raw material source for pulpwood, veneer plywood, and sawlog timber in southern China. As a tree in multiple environments, tree-breeding programs can assess genotype by environment (G × E) interactions and identify the suitable genotype for a specific environment. G × E interactions related to growth traits and soil factors have not been adequately studied for clones of Eucalyptus urophylla and its hybrids. To examine this important question, trials containing 20 clones of E. urophylla and its hybrids were established at three sites in southern China: Shankou (SK), Tiantang (TT), and Xiniujiao (XNJ). These sites each have different soil conditions but similar geographical and climatic conditions. With the data across nearly eight years, average phenotypic trends and broad sense repeatability (H 2 ) were modeled, G×E interactions between clones and diverse soil environments were estimated, genetic gains of clones were calculated, and the adaptabilities of E. urophylla clones in different soil environments were compared. Average survival trends for clones tended to show a moderate decrease while growth traits tended to show sharp increases with age. At the same age, sites were ordered for average survival and growth traits as TT>SK>XNJ while H 2 values for growth traits by site followed the basic order TT>SK>XNJ. The H 2 values for growth traits at SK tended to increase at first, platform, and then smooth with age. The H 2 values for growth traits at TT were high and stable across ages, and those at XNJ tended to undulate largely at a relatively low level across ages. Genetic correlations for growth traits between any pair of sites tended to increase at first and then decrease. A genetic correlation was strong between SK and TT, intermediate between SK and XNJ, and weak between TT and XNJ. It was concluded that: (1) clones tended to be adapted better to an environment with acidic and loamy soil with a clay content of about 45.6%, the soil depth from the surface to parent material about 1.5 m, and the previous vegetation of Eucalypts . (2) The G×E interactions between clones and sites are weaker if the environmental conditions between the sites are similar, and which are stronger if the environmental conditions between the sites are different. (3) The optimum selection age for clones ranged from 1.5 to 3.5 years old, while the optimum selection growth trait is individual tree volume., Competing Interests: The authors declare there are no competing interests., (©2024 Li et al.)

Plant somatic embryogenesis (SE) is an efficient regeneration system for propagation. It involves the regulation of a complex molecular regulatory network encompassing endogenous hormone synthesis, metabolism, and signal transduction processes, induced through exogenous plant growth regulators. Previous studies have focused primarily on traditional propagation methods for Tectona grandis , but there is limited knowledge on SE and its hormonal regulatory mechanisms. In our study, different SE stages, including the nonembryogenic callus (NEC), embryogenic callus (EC), and globular and heart-shaped embryo (E-SEs) stages, were induced in teak cotyledons incubated on MS medium supplemented with 0.1 mg/L thidiazuron (TDZ). Morphological and histological observations indicated that EC primarily originates from the development of embryogenic cell clusters. During SE induction, the levels of six classes of endogenous hormones, IAA, CTK, ETH, ABA, SA, and JA, changed significantly. Transcriptome analysis revealed that endogenous hormones participate in SE induction in teak through various biological processes, such as biosynthesis, metabolism, and signal transduction pathways. We found that IAA biosynthesis primarily occurs through the IAM pathway during these three stages. The ETH receptor kinase gene SERF1 exhibited the highest expression levels in E-SEs. The ABA-, SA-, and JA-related signal transduction genes ABI3 , NPR1 , and JAZ exhibited no differential expression during different stages. Moreover, key encoding genes of SE regulators, including WUS , WOX and SERK , were differentially expressed during SE. In conclusion, this study offers insights into the roles of endogenous hormones and their interactions during SE induction., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Zhou, Yang, Pan, Wang, Han, Qin, Li and Huang.)

Changes in rainfall patterns are important environmental factors affecting plant growth, especially when larger precipitation events and prolonged drought periods occur in subtropical regions. There are many studies on how drought reduces plant biomass through drought-sensitive functional traits, but how excess water affects plant growth and ecophysiology is still poorly understood. Therefore, a greenhouse experiment was conducted on Schima superba (Theaceae), a dominant tree species in subtropical forests and commonly used in forestry, in a closed chamber under control (25% soil water content (SWC) as in local forests), drought stress (D, 15% SWC) and moisture stress (W, 35% SWC). Plant growth and ecophysiological traits related to morphology, leaf gas exchange, water potential and structural traits were measured. Compared to control, S. suberba under dry conditions significantly decreased its aboveground biomass, photosynthetic rate (A), leaf water potential and nitrogen use efficiency, but increased intrinsic water use efficiency, root to shoot ratio and specific root length. S. superba under wet conditions also significantly decreased its total biomass, aboveground biomass and specific root length, while W had no effect on A and leaf water potential. Our results indicate that S. superba shows a decrease in carbon gain under drought stress, but less response under wet conditions. This emphasizes the need to consider the strength and frequency of rainfall pattern changes in future studies because rainfall may either alleviate or intensify the effects of drought stress depending on the moisture level, thus suitable water conditions is important for better management of this tree species in subtropical China., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Phyllosphere microorganisms execute important ecological functions including supporting host plant growth, enhancing host resistance to abiotic stresses, and promoting plant diversity. How leaf developmental stages affect plant-microbiome interactions and phyllosphere microbial community assembly and diversity is poorly understood. In this study, we utilized amplicon sequencing of 16S rRNA and ITS genes to investigate the composition and diversity of microbial communities across different leaf developmental stages of rubber trees. Our findings reveal that endophytic microbial communities, particularly bacterial communities, are more influenced by leaf senescence than by epiphytic communities. The high abundance of metabolism genes in the endosphere of yellow leaves contributes to the degradation and nutrient relocation processes. Nutrient loss leads to a higher abundance of α-Proteobacteria (r-selected microorganisms) in the yellow leaf endosphere, thereby promoting stochastic community assembly. As leaves age, the proportion of microorganisms entering the inner layer of leaves increases, consequently enhancing the diversity of microorganisms in the inner layer of leaves. These results offer insights into the mechanisms governing community assembly and diversity of leaf bacteria and fungi, thereby advancing our understanding of the evolving functions of microbial communities during leaf senescence in general, and for an important tropical crop species in particular., (© 2024. The Author(s).)

Depending on the texture of soil, different physicochemical and microbiological parameters are characterized, and these characteristics are influenced by crop cultivation. Stevia , a popular zero-calorie sweetener crop, is widely cultivated around the world on various soil textures. Sandy loam and clay soil show great differences in physicochemical and biological parameters and are often used for Stevia cultivation. To understand the effects of Stevia cultivation on soil physicochemical and biological features, we investigated the changes of physicochemical and microbiological parameters in sandy loam and clay soil following Stevia cultivation. This study was carried out through different physiological and biochemical assays and microbiomic analysis. The results indicated that the sandy loam soil had significantly lower pH and higher nutrient content in the rhizosphere and bulk soils after the Stevia cultivation. The sandy loam soil maintained higher bacterial diversity and richness than the clay soil after Stevia harvest. Beneficial bacteria such as Dongia, SWB02 , Chryseolinea , Bryobacter and Devosia were enriched in the sandy loam soil; however, bacteria such as RB41 , Haliangium and Ramlibacter , which are unfavorable for nutrient accumulation, predominated in clay soil. Redundancy analysis indicated that the variation in the composition of bacterial community was mainly driven by soil pH, organic matter, total nitrogen, available phosphorus, and microbial biomass phosphorus. This study provides a deeper understanding of physicochemical and microbiological changes in different soil textures after Stevia cultivation and guidance on fertilizer management for Stevia rotational cultivation., Competing Interests: The authors declare there are no competing interests., (©2024 Xu et al.)

SQUAMOSA promoter-binding protein-like ( SPL ) gene family, a group of plant-specific transcription factors, played crucial roles in regulating plant growth, development, signal transduction, and stress response. This study focuses on the SPL gene family in the fast-growing Eucalyptus grandis , employing bioinformatics approaches to identify and analyze the gene physiochemical characteristics, conserved domains, structural composition, chromosomal distribution, phylogenetic relationships, cis-acting elements, and their expression patterns in various tissues and stress treatments. Twenty-three SPL genes were identified in E. grandis , which uneven distributed across seven chromosomes and classified into five groups. Prediction of cis-acting elements revealed that these genes might be related to light, hormone, and stress responses. Furthermore, EgSPL9 and EgSPL23 , mainly expressed in the stem apex and lateral branches, seem to be involved in hormone stress resistance. Our study provides insights into the potential functions of the EgSPL genes in plant growth, stress response, and hormone transduction, offering valuable perspectives for subsequent research into their biological roles., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2024 Lijun An et al.)

The plastid is an essential organelle for its role in photosynthesis and energy production and its genomic information is always employed as important evolutionary markers to explore the relationship among species. Agarwood ( Aquilaria ), prized for its aromatic blend, finds extensive use in various cultures as incense and perfume. Despite its high economic importance, the phylogenetic status among Aquilaria based on plastomes remains ambiguous due to the lack of available plastomic resources. To bridge this knowledge gap, 22 Aquilaria plastomes were newly sequenced, similar variation patterns in this genus were determined, including a shared 16 bp extension of the rps19 gene and seven highly variable regions. The analysis highlighted the highest prevalence of the A/T motif among simple sequence repeats in these plastomes. Further phylogenetic analysis revealed Aquilaria 's phylogenetic implications with an expanded dataset. This comprehensive plastomic resource not only enhances our understanding of Aquilaria evolution but also presents potential molecular markers for DNA barcoding., Competing Interests: The authors declare that they have no conflict of interest.

Understanding the correlation between topography, species biomass and species life stage would allow forest managers to better foster carbon storage in forests. Using census data from a 60-ha plot in south China, we first quantified aboveground biomass (AGB) and how much it varied among different topographies. Next, the specific contribution of 42 dominant species to total aboveground biomass was analyzed for each of the different topographies. We also explored whether these species-topography associations changed, in terms of species' AGB distribution, during each of the three life stages (sapling, juvenile, adult) for these 42 species. Our results showed that the average AGB was 368.79 Mg ha -1 and that it varied noticeably among the four topographies (Low valley, Slope, High valley and Ridge, which were classified by using fuzzy C-mean clustering based on elevation, convexity, and slope). AGB was significantly lower in the two valleys than in the two other topographies. Of the 42 species, 88.1% showed topographic preferences, and 78.6% appeared to exhibit topographic preferences that changed with life stage. Our work highlights the importance of topography and life stage in species biomass distribution and suggests that different combinations of species and life stages, based on species topographic preferences across life stages, may be better suited in different tropical rainforest topographies to maximize carbon storage overall., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Wang, Xu, Li and Li.)

The process of formation of aromatic components for agarwood in Aquilaria sinensis is closely related to endophytic fungi and the result of complex multiple long-term joint interactions with them. However, the interactions between the aromatic components and endophytic fungi remain unclear during the formation of agarwood. In this study, precise mixed solution of hormones, inorganic salts, and fungi was used to induce its formation in A. sinensis , and sample blocks of wood were collected at different times after inoculation. This study showed that the aromatic compounds found in the three treatments of A. sinensis were primarily chromones (31.70-33.65%), terpenes (16.68-27.10%), alkanes (15.99-23.83%), and aromatics (3.13-5.07%). Chromones and terpenes were the primary components that characterized the aroma. The different sampling times had a more pronounced impact on the richness and diversity of endophytic fungal communities in the A. sinensis xylem than the induction treatments. The species annotation of the operational taxonomic units (OTUs) demonstrated that the endophytic fungi were primarily composed of 18 dominant families and 20 dominant genera. A linear regression analysis of the network topology properties with induction time showed that the interactions among the fungal species continued to strengthen, and the network structure tended to become more complex. The terpenes significantly negatively correlated with the Pielou evenness index ( p  < 0.05), while the chromones significantly positively correlated with the OTUs and Shannon indices., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Pang, Zhao, Zhang, Tian, Wu, Deng, Zhang, Li, Liu, Yang, Huang and Zhou.)

Ectomycorrhizal fungi employ different strategies for mycelial growth and host colonization under varying nutrient conditions. However, key genes associated with mycorrhizal interaction should be influenced solely by the inoculation treatment and not by nutrient variations. To utilize subtle nutrient differences and rapidly screen for key genes related to the interaction between Suillus luteus and Pinus massoniana , we performed an inoculation experiment using culture bottles containing high- and low-nutrient media. Interestingly, S. luteus LS88 promoted the growth of P. massoniana seedlings without mature ectomycorrhiza, and the impact of LS88 inoculation on P. massoniana roots was greater than that of nutrient changes. In this study, the resequenced genome of the LS88 strain was utilized for transcriptome analysis of the strain. The analysis indicated that a unique gene encoding glutathione S-transferase (GST) in LS88 is likely involved in colonizing P. massoniana roots. In this study, the GST gene expression was independent of nutrient levels. It was probably induced by P. massoniana and could be used as a marker for S. luteus colonization degree.

Invasive species and their hybrids with native species threaten biodiversity. However, there are few reports on the drought stress adaptability of invasive species Sphagneticola trilobata (L.) Pruski and its hybrid with native species S. calendulacea . In this study, relative water content (RWC), abscisic acid (ABA), reactive oxygen species, antioxidant capacity, and photosynthetic capacity were measured in the hybrid and its parents under drought stress (13% PEG-6000). Under drought stress, the ABA content and RWC in S. trilobata were the highest. RWC decreased by 28% in S. trilobata , 41% in S. calendulacea , and 33% in the hybrid. Activities of the antioxidant enzymes in S. trilobata were the highest, and the accumulation of malondialdehyde (MDA) was the lowest (4.3 μg g -1 ), while it was the highest in S. calendulacea (6.9 μg g -1 ). The maximum photochemical efficiency (F v /F m ) of S. calendulacea was the lowest (0.71), and it was the highest in S. trilobata (7.5) at 8 h under drought stress. The results suggest that the drought resistance of the hybrid was weaker than that of S. trilobata but stronger than that of S. calendulacea . Therefore, the survival of S. calendulacea may be threatened by both the invasive species S. trilobata and the hybrid.

The TRICHOME BIREFRINGENCE-LIKE ( TBL ) gene encodes a class of proteins related to xylan acetylation, which has been shown to play an important role in plant response to environmental stresses. This gene family has been meticulously investigated in Arabidopsis thaliana , whereas there have been no related reports in Eucalyptus grandis . In this study, we identified 49 TBL genes in E. grandis . A conserved amino acid motif was identified, which plays an important role in the execution of the function of TBL gene family members. The expression of TBL genes was generally upregulated in jasmonic acid-treated experiments, whereas it has been found that jasmonic acid activates the expression of genes involved in the defense functions of the plant body, suggesting that TBL genes play an important function in the response of the plant to stress. The principle of the action of TBL genes is supported by the finding that the xylan acetylation process increases the rigidity of the cell wall of the plant body and thus improves the plant's resistance to stress. The results of this study provide new information about the TBL gene family in E. grandis and will help in the study of the evolution, inheritance, and function of TBL genes in E. grandis , while confirming their functions., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The reviewer WH declared a past co-authorship with the author HL to the handling editor., (Copyright © 2024 Tang, Ling, Li and Fan.)

The seeds of Camellia oleifera produce high amount of oil, which can be broadly used in the fields of food, industry, and medicine. However, the molecular regulation mechanisms of seed development and oil accumulation in C. oleifera are unclear. In this study, evolutionary and expression analyses of the MADS-box gene family were performed across the C. oleifera genome for the first time. A total of 86 MADS-box genes ( ColMADS ) were identified, including 60 M-type and 26 MIKC members. More gene duplication events occurred in M-type subfamily (6) than that in MIKC subfamily (2), and SEP-like genes were lost from the MIKC C clade. Furthermore, 8, 15, and 17 differentially expressed ColMADS genes (DEGs) were detected between three developmental stages of seed (S1/S2, S2/S3, and S1/S3), respectively. Among these DEGs, the STK-like ColMADS12 and TT16-like ColMADS17 were highly expressed during the seed formation (S1 and S2), agreeing with their predicted functions to positively regulate the seed organogenesis and oil accumulation. While ColMADS57 and ColMADS07 showed increasing expression level with the seed maturation (S2 and S3), conforming to their potential roles in promoting the seed ripening. In all, these results revealed a critical role of MADS-box genes in the C. oleifera seed development and oil accumulation, which will contribute to the future molecular breeding of C. oleifera ., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2024 Xianzhi Zhang et al.)

Xylan, one of the most important structures and polysaccharides, plays critical roles in plant development, growth, and defense responses to pathogens. Glucuronic acid substitution of xylan (GUX) functions in xylan sidechain decoration, which is involved in a wide range of physiological processes in plants. However, the specifics of GUXs in trees remain unclear. In this study, the characterization and evolution of the GUX family genes in E. grandis , a fast-growing forest tree belonging to the Myrtaceae family, were performed. A total of 23 EgGUXs were identified from the E. grandis genome, of which all members contained motif 2, 3, 5, and 7. All GUX genes were phylogeneticly clustered into five distinct groups. Among them, EgGUX01~EgGUX05 genes were clustered into group III and IV, which were more closely related to the AtGUX1 , AtGUX2 , and AtGUX4 members of Arabidopsis thaliana known to possess glucuronyltransferase activity, while most other members were clustered into group I. The light-responsive elements, hormone-responsive elements, growth and development-responsive elements, and stress-responsive elements were found in the promoter cis-acting elements, suggesting the expression of GUX might also be regulated by abiotic factors. RNA-Seq data confirmed that EgGUX02 , EgGUX03, and EgGUX10 are highly expressed in xylem, and EgGUX09 , EgGUX10, and EgGUX14 were obviously responses to abiotic stresses. The results of this paper will provide a comprehensive determination of the functions of the EgGUX family members, which will further contribute to understanding E. grandis xylan formation.

Herbivorous insects alter biogeochemical cycling within forests, but the magnitude of these impacts, their global variation, and drivers of this variation remain poorly understood. To address this knowledge gap and help improve biogeochemical models, we established a global network of 74 plots within 40 mature, undisturbed broadleaved forests. We analyzed freshly senesced and green leaves for carbon, nitrogen, phosphorus and silica concentrations, foliar production and herbivory, and stand-level nutrient fluxes. We show more nutrient release by insect herbivores at non-outbreak levels in tropical forests than temperate and boreal forests, that these fluxes increase strongly with mean annual temperature, and that they exceed atmospheric deposition inputs in some localities. Thus, background levels of insect herbivory are sufficiently large to both alter ecosystem element cycling and influence terrestrial carbon cycling. Further, climate can affect interactions between natural populations of plants and herbivores with important consequences for global biogeochemical cycles across broadleaved forests., (© 2024. The Author(s).)

Eucalyptus grandis is an important planted hardwood tree worldwide with fast growth and good wood performance. The nitrate transporter (NRT) gene family is a major core involved in nitrogen (N) absorption and utilization in plants, but the comprehensive characterization of NRT genes in E. grandis remains mostly elusive. In this study, a total of 75 EgNRT genes were identified from the genome of E. grandis that were distributed unevenly across ten chromosomes, except Chr9. A phylogenetic analysis showed that the EgNRT proteins could be divided into three classes, namely NRT1, NRT2 and NRT3, which contained 69, 4 and 2 members, respectively. The cis -regulatory elements in the promoter regions of EgNRT genes were mainly involved in phytohormone and stress response. The transcriptome analysis indicated that the differentially expressed genes of leaf and root in E. grandis under different N supply conditions were mainly involved in the metabolic process and plant hormone signal transduction. In addition, the transcriptome-based and RT-qPCR analysis revealed that the expression of 13 EgNRT genes, especially EgNRT1.3 , EgNRT1.38 , EgNRT1.39 and EgNRT1.52 , was significantly upregulated in the root under low-N-supply treatment, suggesting that those genes might play a critical role in root response to nitrate deficiency. Taken together, these results would provide valuable information for characterizing the roles of EgNRTs and facilitate the clarification of the molecular mechanism underlying EgNRT -mediated N absorption and distribution in E. grandis .

Four new species of Russulasubsect.Cyanoxanthinae, viz. Russulaatrochermesina Y.L. Chen & J.F. Liang, R.lavandula Y.L. Chen, B. Chen & J.F. Liang, R.lilaceofusca Y.L. Chen & J.F. Liang and R.perviridis Y.L. Chen, B. Chen & J.F. Liang, from China are proposed, based on morphological and molecular evidence. Russulaatrochermesina can be distinguished by its violet pileus with tuberculate-striate margin, distant lamellae that stain greyish-yellow when bruised, basidiospores ornamented by isolated warts, wide hymenial cystidia on lamellae edges, cystidia content negative reaction in sulphovanillin and branched subterminal cells in pileipellis. Russulalavandula has a purplish-white to violet red pileus with a yellow centre, frequently present lamellulae and furcations, stipe often with pale yellow near the base, isolated basidiospores ornamentation and unbranched cuticular hyphal terminations, while R.lilaceofusca is characterised by its lilac brown to dark brown pileus, crowded lamellae with lamellulae and furcations, stipe often turning reddish-yellow when bruised, subreticulate basidiospores ornamentation and clavate hymenial cystidia often with capitate appendage whose contents that change to reddish-black in sulphovanillin. Russulaperviridis is characterised by its large basidiomata, smooth pileus surface, frequently present lamellulae and furcations, stipe with yellow-brown tinge, globose to broadly ellipsoid basidiospores with subreticulate ornamentation, long hymenial cystidia that turn greyish-black in sulphovanillin and symbiotic with Quercussemecarpifolia . Phylogenetic analyses, based on multi-gene ITS+LSU+mtSSU+ rpb2 , indicate that R.atrochermesina , R.lavandula , R.lilaceofusca and R.perviridis are closely related to R.pallidirosea and R.purpureorosea , R.banwatchanensis , R.lakhanpalii and R.nigrovirens , respectively., Competing Interests: The authors have declared that no competing interests exist., (Yanliu Chen, Bin Chen, Ruoxi Liang, Shengkun Wang, Mengya An, Jinhua Zhang, Jingying Liang, Yaxin Wang, Xuelian Gao, Junfeng Liang.)

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 × 10 7 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.

Hybridization is common between invasive and native species and may produce more adaptive hybrids. The hybrid ( Sphagneticola × guangdongensis ) of Sphagneticola trilobata (an invasive species) and S. calendulacea (a native species) was found in South China. In this study, S. trilobata , S. calendulacea , and Sphagneticola × guangdongensis were used as research materials to explore their adaptability to flooding stress. Under flooding stress, the ethylene content and the expression of key enzyme genes related to ethylene synthesis in Sphagneticola × guangdongensis and S. calendulacea were significantly higher than those in S. trilobata . A large number of adventitious roots and aerenchyma were generated in Sphagneticola × guangdongensis and S. calendulacea . The contents of reactive oxygen species and malondialdehyde in Sphagneticola × guangdongensis and S. calendulacea were lower than those in S. trilobata , and the leaves of S. trilobata were the most severely damaged under flooding stress. The results indicate that hybridization catalyzed the tolerance of Sphagneticola × guangdongensis to flooding stress, and the responses of Sphagneticola × guangdongensis to flooding stress were more similar to that of its native parent. This suggests that hybridization with native relatives is an important way for invasive species to overcome environmental pressure and achieve invasion.

Background: The GRAS gene family is a class of plant-specific transcription factors with important roles in many biological processes, such as signal transduction, disease resistance and stress tolerance, plant growth and development. So far, no information available describes the functions of the GRAS genes in Eucalyptus grandis., Results: A total of 82 GRAS genes were identified with amino acid lengths ranging from 267 to 817 aa, and most EgrGRAS genes had one exon. Members of the GRAS gene family of Eucalyptus grandis are divided into 9 subfamilies with different protein structures, while members of the same subfamily have similar gene structures and conserved motifs. Moreover, these EgrGRAS genes expanded primarily due to segmental duplication. In addition, cis-acting element analysis showed that this family of genes was involved involved in the signal transduction of various plant hormones, growth and development, and stress response. The qRT-PCR data indicated that 18 EgrGRAS genes significantly responded to hormonal and abiotic stresses. Among them, the expression of EgrGRAS13, EgrGRAS68 and EgrGRAS55 genes was significantly up-regulated during the treatment period, and it was hypothesised that members of the EgrGRAS family play an important role in stress tolerance., Conclusions: In this study, the phylogenetic relationship, conserved domains, cis-elements and expression patterns of GRAS gene family of Eucalyptus grandis were analyzed, which filled the gap in the identification of GRAS gene family of Eucalyptus grandis and laid the foundation for analyzing the function of EgrGRAS gene in hormone and stress response., (© 2024. The Author(s).)

The 2-(2-phenethyl)chromones (PECs) are the signature constituents responsible for the fragrance and pharmacological properties of agarwood. O-Methyltransferases (OMTs) are necessary for the biosynthesis of methylated PECs, but there is little known about OMTs in Aquilaria sinensis. In this study, we identified 29 OMT genes from the A. sinensis genome. Expression analysis showed they were differentially expressed in different tissues and responded to drill wounding. Comprehensive analysis of the gene expression and methylated PEC content revealed that AsOMT2, AsOMT8, AsOMT11, AsOMT16, and AsOMT28 could potentially be involved in methylated PECs biosynthesis. In vitro enzyme assays and functional analysis in Nicotiana benthamiana demonstrated that AsOMT11 and AsOMT16 could methylate 6-hydroxy-2-(2-phenylethyl)chromone to form 6-methoxy-2-(2-phenylethyl)chromone. A transient overexpression experiment in the variety 'Qi-Nan' revealed that AsOMT11 and AsOMT16 could significantly promote the accumulation of three major methylated PECs. Our results provide candidate genes for the mass production of methylated PECs using synthetic biology., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

The invasion of Mikania micrantha by climbing and covering trees has rapidly caused the death of many shrubs and trees, seriously endangering forest biodiversity. In this study, M. micrantha seedlings were planted together with local tree species (Cryptocarya concinna) to simulate the process of M. micrantha climbing under the forest. We found that the upper part of the M. micrantha stem lost its support after climbing to the top of the tree, grew in a turning and creeping manner, and then grew branches rapidly to cover the tree canopy. Then, we simulated the branching process through turning treatment. We found that a large number of branches had been formed near the turning part of the M. micrantha stem (TP). Compared with the upper part of the main stem (UP), the contents of plant hormones (auxin, cytokinin, gibberellin), soluble sugars (sucrose, glucose, fructose) and trehalose-6-phosphate (T6P) were significantly accumulated at TP. Further combining the transcriptome data of different parts of the main stem under erect or turning treatment, a hypothetical regulation model to illustrate how M. micrantha can quickly cover trees was proposed based on the regulation of sugars and hormones on plant branching; that is, the lack of support after ascending the top of the tree led to turning growth of the main stem, and the enhancement of sugars and T6P levels in the TP may first drive the release of nearby dormant buds. Plant hormone accumulation may regulate the entrance of buds into sustained growth and maintain the elongation of branches together with sugars to successfully covering trees., (© 2024. The Author(s).)

Host specialization plays a critical role in the ecology and evolution of plant-microbe symbiosis. Theory predicts that host specialization is associated with microbial genome streamlining and is influenced by the abundance of host species, both of which can vary across latitudes, leading to a latitudinal gradient in host specificity. Here, we quantified the host specificity and composition of plant-bacteria symbioses on leaves across 329 tree species spanning a latitudinal gradient. Our analysis revealed a predominance of host-specialized leaf bacteria. The degree of host specificity was negatively correlated with bacterial genome size and the local abundance of host plants. Additionally, we found an increased host specificity at lower latitudes, aligning with the high prevalence of small bacterial genomes and rare host species in the tropics. These findings underscore the importance of genome streamlining and host abundance in the evolution of host specificity in plant-associated bacteria along the latitudinal gradient., (© 2024 The Author(s). Ecology Letters published by John Wiley & Sons Ltd.)

To compare the bioactive compounds in agarwood induced by different methods in Aquilaria sinensis(Lour.) Gilg trees, a two dimensional thin layer chromatograph(2D-TLC) combined with effect directive analysis(EDA) was developed. Three antioxidants were found by 2D-TLC-DPPH and further identified as 2-(2-phenylethyl) chromones(PECs) with LC-MS/MS. The 3 antioxidants decreased along agarwood formation and their compositions in drilling induced agarwood differed with those in microbe culture induced agarwood. Further study showed NaCl treatment promoted antioxidants accumulation in agarwood induced by drilling or hot drilling. Hot drilling combined with salty stimulation was most efficient in some chemicals accumulation, which were identified as PECs with antioxidant, tyrosinase or β-glucosidase inhibiting activities by 2D-TLC-EDA-LC-MS/MS. This study provided a 2D-TLC-EDA-LC-MS/MS method for bioactive compounds screen and qualification of agarwood. Based on this method, non-conventional methods were found to accelerate the accumulation of some bioactive PECs in A. sinensis trees., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

A comprehensive understanding of the molecular mechanisms underlying microbial catabolism of dibutyl phthalate (DBP) is still lacking. Here, we newly isolated a bacterial strain identified as Pseudomonas aeruginosa PS1 with high efficiency of DBP degradation. The degradation ratios of DBP at 100-1000 mg/L by this strain reached 80-99 % within 72 h without a lag phase. A rare DBP-degradation pathway containing two monobutyl phthalate-catabolism steps was proposed based on intermediates identified by HPLC-TOF-MS/MS. In combination with genomic and transcriptomic analyses, we identified 66 key genes involved in DBP biodegradation and revealed the genetic basis for a new complete catabolic pathway from DBP to Succinyl-CoA or Acetyl-CoA in the genus Pseudomonas for the first time. Notably, we found that a series of homologous genes in Pht and Pca clusters were simultaneously activated under DBP exposure and some key intermediate degradation related gene clusters including Pht, Pca, Xyl, Ben, and Cat exhibited a favorable coexisting pattern, which contributed the high-efficient DBP degradation ability and strong adaptability to this strain. Overall, these results broaden the knowledge of the catabolic diversity of DBP in microorganisms and enhance our understanding of the molecular mechanism underlying DBP biodegradation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reports in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Phosphorus (P), a critical macronutrient for plant growth and reproduction, is primarily acquired and translocated in the form of inorganic phosphate (Pi) by roots. Pi deficiency is widespread in many natural ecosystems, including forest plantations, due to its slow movement and easy fixation in soils. Plants have evolved complex and delicate regulation mechanisms on molecular and physiological levels to cope with Pi deficiency. Over the past two decades, extensive research has been performed to decipher the underlying molecular mechanisms that regulate the Pi starvation responses (PSR) in plants. This review highlights the prospects of Pi uptake, transport, and signaling in woody plants based on the backbone of model and crop plants. In addition, this review also highlights the interactions between phosphorus and other mineral nutrients such as Nitrogen (N) and Iron (Fe). Finally, this review discusses the challenges and potential future directions of Pi research in woody plants, including characterizing the woody-specific regulatory mechanisms of Pi signaling and evaluating the regulatory roles of Pi on woody-specific traits such as wood formation and ultimately generating high Phosphorus Use Efficiency (PUE) woody plants., Competing Interests: The authors declare that they have no conflict of interest.

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&#95;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.

Acacia melanoxylon is well known as a valuable commercial tree species owing to its high-quality heartwood (HW) products. However, the metabolism and regulatory mechanism of heartwood during wood development remain largely unclear. In this study, both microscopic observation and content determination proved that total amount of starches decreased and phenolics and flavonoids increased gradually from sapwood (SW) to HW. We also obtained the metabolite profiles of 10 metabolites related to phenolics and flavonoids during HW formation by metabolomics. Additionally, we collected a comprehensive overview of genes associated with the biosynthesis of sugars, terpenoids, phenolics, and flavonoids using RNA-seq. A total of ninety-one genes related to HW formation were identified. The transcripts related to plant hormones, programmed cell death (PCD), and dehydration were increased in transition zone (TZ) than in SW. The results of RT-PCR showed that the relative expression level of genes and transcription factors was also high in the TZ, regardless of the horizontal or vertical direction of the trunk. Therefore, the HW formation took place in the TZ for A. melanoxylon from molecular level, and potentially connected to plant hormones, PCD, and cell dehydration. Besides, the increased expression of sugar and terpenoid biosynthesis-related genes in TZ further confirmed the close connection between terpenoid biosynthesis and carbohydrate metabolites of A. melanoxylon. Furthermore, the integrated analysis of metabolism data and RNA-seq data showed the key transcription factors (TFs) regulating flavonoids and phenolics accumulation in HW, including negative correlation TFs (WRKY, MYB) and positive correlation TFs (AP2, bZIP, CBF, PB1, and TCP). And, the genes and metabolites from phenylpropanoid and flavonoid metabolism and biosynthesis were up-regulated and largely accumulated in TZ and HW, respectively. The findings of this research provide a basis for comprehending the buildup of metabolites and the molecular regulatory processes of HW formation in A. melanoxylon., (© 2024. The Author(s).)

Introduction: Tropical forests are characterized by intricate mosaics of species-rich and structurally complex forest communities. Evaluating the functional vulnerability of distinct community patches is of significant importance in establishing conservation priorities within tropical forests. However, previous assessments of functional vulnerability in tropical forests have often focused solely on isolated factors or individual disturbance events, with limited consideration for a broad spectrum of disturbances and the responses of diverse species., Methods: We assessed the functional vulnerability of woody plant communities in a 60-ha dynamic plot within a tropical montane rainforest by conducting in silico simulations of a wide range disturbances. These simulations combined plant functional traits and community properties, including the distribution of functional redundancy across the entire trait space, the distribution of abundance across species, and the relationship between species trait distinctiveness and species abundance. We also investigated the spatial distribution patterns of functional vulnerability and their scale effects, and employed a spatial autoregressive model to examine the relationships between both biotic and abiotic factors and functional vulnerability at different scales., Results: The functional vulnerability of tropical montane rainforest woody plant communities was generally high (the functional vulnerability of observed communities was very close to that of the most vulnerable virtual community, with a value of 72.41% on average at the 20m×20m quadrat scale), and they exhibited significant spatial heterogeneity. Functional vulnerability decreased with increasing spatial scale and the influence of both biotic and abiotic factors on functional vulnerability was regulated by spatial scale, with soil properties playing a dominant role., Discussion: Our study provides new specific insights into the comprehensive assessment of functional vulnerability in the tropical rainforest. We highlighted that functional vulnerabilities of woody plant communities and their sensitivity to environmental factors varied significantly within and across spatial scales in the tropical rainforest landscape. Preserving and maintaining the functionality of tropical ecosystems should take into consideration the variations in functional vulnerability among different plant communities and their sensitivity to environmental factors., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Sun, Yao, Xu, Zhou and Zang.)

Soil microbial necromass carbon is an important component of the soil organic carbon (SOC) pool which helps to improve soil fertility and texture. However, the spatial pattern and variation mechanisms of fungal- and bacterial-derived necromass carbon at local scales in tropical rainforests are uncertain. This study showed that microbial necromass carbon and its proportion in SOC in tropical montane rainforest exhibited large spatial variation and significant autocorrelation, with significant high-high and low-low clustering patterns. Microbial necromass carbon accounted for approximately one-third of SOC, and the fungal-derived microbial necromass carbon and its proportion in SOC were, on average, approximately five times greater than those of bacterial-derived necromass. Structural equation models indicated that soil properties (SOC, total nitrogen, total phosphorus) and topographic features (elevation, convexity, and aspect) had significant positive effects on microbial necromass carbon concentrations, but negative effects on its proportions in SOC (especially the carbon:nitrogen ratio). Plant biomass also had significant negative effects on the proportion of microbial necromass carbon in SOC, but was not correlated with its concentration. The different spatial variation mechanisms of microbial necromass carbon and their proportions in SOC are possibly related to a slower accumulation rate of microbial necromass carbon than of plant-derived organic carbon. Geographic spatial correlations can significantly improve the microbial necromass carbon model fit, and low sampling resolution may lead to large uncertainties in estimating soil carbon dynamics at specific sites. Our work will be valuable for understanding microbial necromass carbon variation in tropical forests and soil carbon prediction model construction with microbial participation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Eucalyptus is a widely planted hardwood tree species due to its fast growth, superior wood properties and adaptability. However, the post-transcriptional regulatory mechanisms controlling tissue development and stress responses in Eucalyptus remain poorly understood. In this study, we performed a comprehensive analysis of the gene expression profile and the alternative splicing (AS) landscape of E. grandis using strand-specific RNA-Seq, which encompassed 201 libraries including different organs, developmental stages, and environmental stresses. We identified 10 416 genes (33.49%) that underwent AS, and numerous differentially expressed and/or differential AS genes involved in critical biological processes, such as primary-to-secondary growth transition of stems, adventitious root formation, aging and responses to phosphorus- or boron-deficiency. Co-expression analysis of AS events and gene expression patterns highlighted the potential upstream regulatory role of AS events in multiple processes. Additionally, we highlighted the lignin biosynthetic pathway to showcase the potential regulatory functions of AS events in the KNAT3 and IRL3 genes within this pathway. Our high-quality expression atlas and AS landscape serve as valuable resources for unravelling the genetic control of woody plant development, long-term adaptation, and understanding transcriptional diversity in Eucalyptus. Researchers can conveniently access these resources through the interactive ePlant browser (https://bar.utoronto.ca/eplant&#95;eucalyptus)., (© 2024 John Wiley & Sons Ltd.)

Recently, some new Qi-Nan clones of Aquilaria sinensis (Lour.) Spreng which intensively produces high-quality agarwood have been identified and propagated through grafting techniques. Previous studies have primarily focused on ordinary A. sinensis and the differences in composition when compared to Qi-Nan and ordinary A. sinensis . There are few studies on the formation mechanism of Qi-Nan agarwood and the dynamic changes in components and endophytic fungi during the induction process. In this paper, the characteristics, chemical composition, and changes in endophytic fungi of Qi-Nan agarwood induced after 1 year, 2 years, and 3 years were studied, and Qi-Nan white wood was used as the control. The results showed that the yield of Qi-Nan agarwood continued to increase with the induction time over a period of 3 years, while the content of alcohol extract from Qi-Nan agarwood reached its peak at two years. During the formation of agarwood, starch and soluble sugars in xylem rays and interxylary phloem are consumed and reduced. Most of the oily substances in agarwood were filled in xylem ray cells and interxylary phloem, and a small amount was filled in xylem vessels. The main components of Qi-Nan agarwood are also chromones and sesquiterpenes. With an increasing induction time, the content of sesquiterpenes increased, while the content of chromones decreased. The most abundant chromones in Qi-Nan agarwood were 2-(2-Phenethyl) chromone, 2-[2-(3-Methoxy-4-hydroxyphenyl) ethyl] chromone, and2-[2-(4-Methoxyphenyl) ethyl] chromone. Significant differences were observed in the species of the endophytic fungi found in Qi-Nan agarwood at different induction times. A total of 4 phyla, 73 orders, and 448 genera were found in Qi-Nan agarwood dominated by Ascomycota and Basidiomycota . Different induction times had a significant effect on the diversity of the endophytic fungal community in Qi-Nan. After the induction of agarwood formation, the diversity of Qi-Nan endophytic fungi decreased. Correlation analysis showed that there was a significant positive correlation between endophytic fungi and the yield, alcohol extract content, sesquiterpene content, and chromone content of Qi-Nan agarwood, which indicated that endophytic fungi play a role in promoting the formation of Qi-Nan agarwood. Qi-Nan agarwood produced at different induction times exhibited strong antioxidant capacity. DPPH free radical scavenging activity and reactive oxygen species clearance activity were significantly positively correlated with the content of sesquiterpenes and chromones in Qi-Nan agarwood., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Li, Fang, Cui, Hong, Liu, Li, Hu and Xu.)

The transcription factor is an essential factor for regulating the responses of plants to external stimuli. The WRKY protein is a superfamily of plant transcription factors involved in response to various stresses (e.g., cold, heat, salt, drought, ions, pathogens, and insects). During angiosperm evolution, the number and function of WRKY transcription factors constantly change. After suffering from long-term environmental battering, plants of different evolutionary statuses ultimately retained different numbers of WRKY family members. The WRKY family of proteins is generally divided into three large categories of angiosperms, owing to their conserved domain and three-dimensional structures. The WRKY transcription factors mediate plant adaptation to various environments via participating in various biological pathways, such as ROS (reactive oxygen species) and hormone signaling pathways, further regulating plant enzyme systems, stomatal closure, and leaf shrinkage physiological responses. This article analyzed the evolution of the WRKY family in angiosperms and its functions in responding to various external environments, especially the function and evolution in Magnoliaceae plants. It helps to gain a deeper understanding of the evolution and functional diversity of the WRKY family and provides theoretical and experimental references for studying the molecular mechanisms of environmental stress.

Acacia melanoxylon is a fast-growing macrophanerophyte with strong adaptability whose leaf enables heteromorphic development. Light is one of the essential environmental factors that induces the development of the heteroblastic leaf of A. melanoxylon , but its mechanism is unclear. In this study, the seedlings of A. melanoxylon clones were treated with weak light (shading net with 40% of regular light transmittance) and normal light (control) conditions for 90 d and a follow-up observation. The results show that the seedlings' growth and biomass accumulation were inhibited under weak light. After 60 days of treatment, phyllodes were raised under the control condition while the remaining compound was raised under weak light. The balance of root, stem, and leaf biomass changed to 15:11:74 under weak light, while it was 40:15:45 under control conditions. After comparing the anatomical structures of the compound leaves and phyllode, they were shown to have their own strategies for staying hydrated, while phyllodes were more able to control water loss and adapt to intense light. The compound leaves exhibited elevated levels of K, Cu, Ca, and Mg, increased antioxidant enzyme activity and proline content, and higher concentrations of chlorophyll a, carotenoids, ABA, CTK, and GA. However, they displayed a relatively limited photosynthetic capacity. Phyllodes exhibited higher levels of Fe, cellulose, lignin, IAA content, and high photosynthetic capacity with a higher maximum net photosynthetic rate, light compensation point, dark respiration rate, and water use efficiency. The comparative analysis of compound leaves and phyllodes provides a basis for understanding the diverse survival strategies that heteroblastic plants employ to adapt to environmental changes.

Suillus bovinus is a wild edible ectomycorrhizal fungus with important economic and ecological value, which often forms an ectomycorrhiza with pine trees. We know little about the mechanisms associated with the metabolism and symbiosis of S. bovinus and its effects on the nutritional value. In this study, the whole-genome sequencing of S. bovinus was performed using Illumina, HiFi, and Hi-C technologies, and the sequencing data were subjected to genome assembly, gene prediction, and functional annotation to obtain a high-quality chromosome-level genome of S. bovinus . The final assembly of the S. bovinus genome includes 12 chromosomes, with a total length of 43.03 Mb, a GC content of 46.58%, and a contig N50 size of 3.78 Mb. A total of 11,199 coding protein sequences were predicted from genome annotation. The S. bovinus genome contains a large number of small secreted proteins (SSPs) and genes that encode enzymes related to carbohydrates, as well as genes related to terpenoids, auxin, and lipochitooligosaccharides. These genes may contribute to symbiotic processes. The whole-genome sequencing and genetic information provide a theoretical basis for a deeper understanding of the mechanism of the mycorrhizal symbiosis of S. bovinus and can serve as a reference for comparative genomics of ectomycorrhizal fungi.