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As climatic and geographical conditions change in the future, species’ habitats will also change. Phoebe zhennan is a national second-level key protected wild plant in China with extremely high economic value and landscape value. In order to better protect the resources of P. zhennan and achieve the goal of the sustainable development of P. zhennan resources, we predict potential suitable areas for P. zhennan under different scenarios in the future. We collect the current distribution data of P. zhennan, and in combination with nine climate factors and three geographical factors, use the MaxEnt ecological niche model and ArcGIS geographic information system software to predict and analyze potential suitable areas for P. zhennan in different climate scenarios in the future. The result shows that more accurate prediction results can be obtained by using China’s climatic and geographical data before clipping as environmental variables. The precipitation of the warmest quarter and the slope are the main influencing factors in the prediction of potential suitable areas for P. zhennan. The future potential suitable areas for P. zhennan are mainly distributed in the central–southern and southern regions of China, with a tendency to expand towards the Tibet Autonomous Region and the northeast. The suitable habitat area will increase significantly, and the highly suitable habitat area will be more concentrated. These research results can provide valuable references for the effective protection of existing P. zhennan populations, the cultivation of P. zhennan within suitable habitats in the future, the establishment of a P. zhennan reserve, and the promotion of the sustainable utilization of P. zhennan resources.

Nanmu (Phoebe zhennan) is an extremely valuable tree plant that is the main source of famous “golden-thread nanmu” wood. The potential metabolites and gene regulation mechanisms involved in golden thread formation are poorly understood, even though the color change from sapwood to heartwood has been investigated in several tree plants. Here, five radial tissues from sapwood to heartwood were compared via integrative metabolomic and transcriptomic analysis to reveal the secondary metabolites and molecular mechanisms involved in golden thread formation. During heartwood formation, gradual starch grain loss is accompanied by the cell lumen deposition of lipids and color-related extractives. Extractives of 20 phenylpropanoids accumulated in heartwood, including cinnamic acids and derivatives, coumarin acid derivatives, and flavonoids, which were identified as being closely related to the golden thread. Phenylpropanoids co-occurring with abundant accumulated metabolites of prenol lipids, fatty acyls, steroids, and steroid derivatives may greatly contribute to the characteristics of golden thread formation. Additionally, the expression of nine genes whose products catalyze phenylpropanoid and flavonoids biosynthesis was upregulated in the transition zone, then accumulated and used to color the heartwood. The expression levels of transcription factors (e.g., MYB, bHLH, and WRKY) that act as the major regulatory factors in the synthesis and deposition of phenylpropanoid and flavonoids responsible for golden thread formation were also higher than in sapwood. Our results not only explain golden thread formation in nanmu, but also broaden current knowledge of special wood color formation mechanisms. This work provides a framework for future research focused on improving wood color.

(Gold Phoebe) is a threatened tree species in China and a valuable and important source of wood and bioactive compounds used in medicine. Apart from anthropogenic disturbances, several biotic constraints currently restrict its growth and development. However, little attention has been given to building adaptive strategies for its conservation by examining its morphological and physio-biochemical responses to drought stress, and the role of fertilizers on these responses. A randomized experimental design was used to investigate the effects of two levels of irrigation (well-watered and drought-stressed) and phosphorous (P) fertilization treatment (with and without P) to assess the morphological and physio-biochemical responses of seedlings to drought stress. In addition, we evaluated whether P application could mitigate the negative impacts of drought on plant growth and metabolism. Drought stress had a significant negative effect on the growth and metabolic processes of . Despite this, reduced leaf area, limited stomatal conductance, reduced transpiration rate, increased water use efficiency, enhanced antioxidant enzymes activities, and osmolytes accumulation suggested that the species has good adaptive strategies for tolerating drought stress. Application of P had a significant positive effect on root biomass, signifying its improved water extracting capacity from the soil. Moreover, P fertilization significantly increased leaf relative water content, net photosynthetic rate, and maximal quantum efficiency of PSII under drought stress conditions. This may be attributable to several factors, such as enhanced root biomass, decreased malondialdehyde content, and the up-regulation of chloroplast pigments, osmolytes, and nitrogenous compounds. However, P application had only a slight or negligible effect on the growth and metabolism of well-watered plants. In conclusion, has a strong capability for drought resistance, while P application facilitates and improves drought tolerance mostly through physio-biochemical adjustments, regardless of water availability. It is imperative to explore the underlying metabolic mechanisms and effects of different levels of P fertilization on under drought conditions in order to design appropriate conservation and management strategies for this species, which is at risk of extinction.

Nanmu (Phoebe zhennan) has a unique fragrance and is a high-quality tree species for forest conservation. The types and contents of volatile compounds in different tissues of nanmu wood are different, and the study of its volatile metabolites can help us to understand the source of its fragrance and functions. In order to explore the metabolites related to the wood fragrance of nanmu and to find out the unique volatile substances in the heartwood, gas chromatography–mass spectrometry (GC-MS) was performed to analyze the non-targeted metabolomics in five radial tissues from the sapwood to the heartwood of nanmu. A total of 53 volatile metabolites belonging to 11 classes were detected in all tissues, including terpenes, aromatic hydrocarbons, organoheterocyclics, phenols, esters, organic acids, alcohols, alkaloids, alkane, indoles derivatives, and others. And most of the volatile metabolites were identified for the first time in nanmu wood. Among them, terpenes and aromatic hydrocarbons were the main volatile components. In addition, 22 differential metabolites were screened from HW and SW, HW, and TZ via metabolomic analysis. Among these DAMs, three volatile metabolites (cadinene, a sesquiterpenoid; p-cymene, a monoterpenoid; 1,3,5-triisopropylbenzene, an aromatic hydrocarbon) contributed heavily to the characteristic fragrance of the heartwood. Additionally, the expression of transcripts showed that the unigenes in the terpenoid biosynthesis pathway were especially up-regulated in the SW. Therefore, we speculated that fragrance-related metabolites were synthesized in SW and then deposited in heartwood during sapwood transformed to heartwood. The expression levels of transcription factors (e.g., WRKY, C2H2, NAC) acted as the major regulatory factors in the synthesis of terpenoid. The results lay the foundations for further studies on the formation mechanism of fragrance components in nanmu wood and also provide a reference for the further development and utilization of nanmu wood.

Phoebe zhennan S. K. Lee & F. N. Wei is a valuable endemic species in China, widely recognized for its high-quality timber and ornamental value. It has been classified as an endangered species under national protection, with its primary distribution areas including Guizhou, Sichuan, and Hunan. Investigating the genetic diversity (GD) of this species plays a crucial role in developing effective strategies for its conservation and sustainable utilization. Nevertheless, the progress in molecular marker development has been constrained by the scarcity of reported reference genomes for P. zhennan . In this study, the genomic gap of the endangered and precious tree species P. zhennan was filled. The simple sequence repeat (SSR) markers of the P. zhennan genome were analyzed using magnetic bead enrichment technology. A total of 794,128 SSR loci were identified. From a random selection of 108 primer pairs, 20 primer pairs with high polymorphism and excellent stability were screened and subsequently utilized to assess the GD of 24 Phoebe populations comprising 174 individuals primarily from Guizhou Province. The results demonstrated that the SSR loci were predominantly dinucleotide repeats (accounting for 54.31%), among which the AG/CT motif exhibited the highest frequency. The polymorphism information content (PIC) of the 20 SSR primer pairs ranged from 0.777 to 0.903, with an average value of 0.859, reflecting their substantial polymorphism. The Shannon information index of the Guizhou P. zhennan population ranged from 1.196 to 1.928, with an average value of 1.518. The Nei’s genetic diversity index (H) varied between 0.661 and 0.832, averaging 0.743. The SN population exhibited relatively high genetic diversity, whereas the MT population demonstrated relatively low genetic diversity. Further investigation revealed that the populations in Gulin, Sichuan; Zigong, Sichuan; Tongnan, Chongqing; and Baijia, Hunan possessed high and stable genetic diversity values. Genetic differentiation analysis indicated that the genetic variation within the Guizhou P. zhennan population primarily stemmed from intra-population variation. Additionally, frequent gene flow was observed among populations, with alleles being widely distributed across populations. Based on the phylogenetic tree, the species Phoebe bournei , Phoebe sheareri , and Phoebe chekiangensis , as well as the populations of P. zhennan from different regions, were clearly differentiated. The SSR molecular markers developed in this study confirmed at the molecular level that these species represent distinct evolutionary lineages. These findings provide valuable SSR molecular markers and a robust scientific foundation for breeding programs, species identification, and genetic diversity studies of germplasm resources within the genus Phoebe .

Phoebe zhennan is a Chinese endemic and valuable timber species of Phoebe (Lauraceae). It is known for its fragrant, high‐value wood and is the primary source of the renowned “golden‐thread nanmu.” In this study, we present a chromosome‐level genome assembly of P. zhennan , consisting of 12 chromosomes (979.28 Mb; scaffold N50: 87.69 Mb) with an estimated 26,262 protein‐coding genes. Whole‐genome duplication (WGD) analysis revealed that P . zhennan has undergone two WGD events: an older one shared by Magnoliales and Laurales, and a younger one shared by Lauraceae and Calycanthaceae species. Phylogenetic analysis showed that magnoliids (together with Chloranthales) form a sister clade to monocots. We identified 197 members of the MYB gene family and further selected 44 MYB genes that may be associated with phenylpropanoid lignin biosynthesis, including 28 genes acting as positive regulatory transcription factors and 16 as negative regulators. Gene expression analysis indicated that PzMYB6 is highly expressed in the cambium, suggesting it may play a critical regulatory role in the lignin biosynthesis pathway of P. zhennan . Overall, this chromosome‐level reference genome provides new insights into the genome evolution of Phoebe and offers essential genetic resources for the rational utilization and conservation of this valuable timber species. 楠木是中国特有的珍贵木材树种, 以材质芬芳、经济价值高著称, 是名贵木材“金丝楠木”的主要来源。本研究首次报道了染色体级别的楠木基因组图谱, 其中包含12条染色体(979.28 Mb；Scaffold N50:87.69 Mb), 并预测出26,262个蛋白质编码基因。全基因组复制(WGD)分析表明, 楠木经历了两次WGD事件: 较古老事件为木兰目和樟目植物共享, 较近期事件为樟科和蜡梅科植物共享。系统发育分析显示, 木兰类植物(与金粟兰目共同)形成单子叶植物的姐妹支系。本研究鉴定了197个MYB基因家族成员, 并进一步筛选出44个可能与苯丙烷类木质素生物合成相关的MYB基因, 其中28个为正调控转录因子, 16个为负调控转录因子。基因表达分析显示, PzMYB6 在形成层中高表达, 提示该基因可能在楠木木质素生物合成途径中起关键调控作用。综上, 楠木染色体级别基因组图谱为樟科楠属植物的基因组进化提供了新见解, 也为该珍贵木材树种的合理利用和保护提供了重要的遗传资源。 Phoebe zhennan is a treasured and endangered timber species native to China, prized for its aromatic fragrance, durability, and striking wood grain. However, the lack of genetic resources has long impeded both its conservation and a deeper understanding of the biological basis for its superior wood properties. In this study, we successfully sequenced and assembled the complete genome of P. zhennan . Our analyses uncovered two ancient whole‐genome duplication events in its evolutionary history, which likely facilitated species diversification and the emergence of its distinctive traits. Phylogenetic reconstruction further resolved the phylogenetic position of magnoliids, revealing a closer relationship to monocots than to eudicots. Most importantly, we identified key genes involved in lignin biosynthesis—the primary structural component of wood. Among these, the transcription factor gene PzMYB6 stood out as a master regulator highly expressed in the trunk cambium, which coordinates the developmental processes that lead to the formation of its robust and highly valued timber. This high‐quality genome assembly serves as a crucial resource for informing conservation strategies, monitoring genetic diversity in wild populations, and advancing the breeding of superior cultivars for sustainable utilization. This study provides the first chromosome‐level genome of Phoebe zhennan , serving as an essential foundation for its genetic conservation and breeding programs. We identified key genes—particularly a master regulator, PzMYB6—that control lignin synthesis, the process that makes wood strong and durable. This discovery opens possibilities for molecular breeding to improve wood quality. The genomic data can be used to assess genetic diversity and wild population health, design effective nature reserves, and develop genetic markers to assist in selecting superior trees for reforestation and sustainable cultivation. 楠木是我国特有的珍稀濒危木材树种, 因其木质芬芳、纹理华美且耐腐性强而备受珍视。然而, 遗传资源的匮乏长期制约着楠木的保护工作, 也阻碍了对其优质木材特性生物学基础的深入解析。本研究成功完成了楠木全基因组的测序与组装, 首次获取了该物种的完整遗传图谱。分析发现, 楠木在演化过程中经历了两次全基因组复制事件, 这可能是推动其进化并形成独特性状的重要动力。系统发育分析进一步明确了木兰类植物的系统位置, 研究显示其与单子叶植物的亲缘关系较双子叶植物更近。尤为关键的是, 本研究鉴定出一系列参与木质素合成的关键基因。其中转录因子基因 PzMYB6 在楠木树干形成层中高度活跃, 如同一个“总控制开关”, 协调着优质木材的发育和形成过程。这份高质量的基因组图谱将为楠木制定精准保护策略, 监测野生种群遗传多样性及选育优良品种实现可持续利用提供重要的遗传资源。 本研究为珍贵濒危木材树种楠木提供了首个染色体级别的基因组图谱, 为其遗传资源保护和育种奠定了重要基础。 本研究鉴定了控制木质素合成的关键基因, 特别是主调控因子 PzMYB6 基因。这项发现为通过分子育种技术改良木材品质提供了可能。 楠木基因组数据可用于评估遗传多样性和野生种群生存状况, 规划设计高效的自然保护区, 并开发遗传标记以辅助选育用于造林和可持续栽培的优良树种。

Wood essential oil and wood products with special fragrances are high value-added forest products. Despite the availability of essential oil and volatile organic compounds (VOCs) from Phoebe zhennan wood, their variation and dependence on tree age have not been examined. After essential oil extraction and wood processing, the yields and compositions of essential oils and VOCs in wood from P. zhennan trees of different ages (10a, 30a, and 80a) were determined. The yield of essential oil from 30a wood was significantly greater than that from 10a and 80a wood. Liquid chromatography–mass spectrometry (LC−MS) and gas chromatography−mass spectrometry (GC−MS) revealed 672 and 41 volatile compounds, respectively, in the essential oil and wood, the majority of which exhibited large fluctuations in relative content and composition depending on tree age. Sesquiterpenoids, fatty acids and conjugates may greatly contribute to the main components of essential oil from wood. Almost all major sesquiterpenoid compounds, such as caryophyllene α-oxide, eudesmo, and cubebene, were identified in the essential oils from the 30a and 80a wood, and their relative contents were much greater than those in the 10a wood. The main components of the wood fragrance were sesquiterpenoids. The types and relative contents of sesquiterpenoids from wood increased with tree age. These results suggest that choosing wood from trees of a suitable age will significantly improve the efficiency of wood utilization.

Background Phoebe zhennan , commonly known as “golden-thread nanmu,” is one of the most valuable and protected tree species in China. An accurate understanding of the population genetic structure and its environmental factors is of significance for the protection and selection of new P. zhennan varieties. Results Sixteen nSSR and six cpSSR markers were used to determine the genetic diversity and population structure of P. zhennan and the effect of environmental factors on the genetic structure. The nSSR markers identified a total of 451 number of alleles (Na), while cpSSR markers detected 20 Na . A relative high level of genetic diversity was observed in the P. zhennan population evidenced by high Shannon’s information index ( I ) of 0.671 and 2.294 based on cpSSR and nSSR datasets. The low value of fixation index ( F ) observed from the nSSR dataset indicated low breeding within the population. The genetic differentiation was mainly detected within populations (only 28% and 13% of the variance being between populations according to the nSSR and cpSSR datasets). Among them, the HNSZX ( H  = 0.469) and SCSZZ ( I  = 1.943) populations exhibited the highest level of genetic diversity, while the HNXXT ( H  = 0.041) and SCLJS ( I  = 0.943) populations exhibited the lowest level of genetic diversity. The average genetic differentiation coefficient ( Fst ) and gene flow ( Nm ) were 0.022–0.128 and 1.698–11.373, respectively, which indicated a moderate level of genetic differentiation and a high level of gene flow. STRUCTURE, neighbor-joining clustering, and principal coordinate analysis divided 543 individuals into two or three categories based on the nSSR or cpSSR datasets. Four temperature, three precipitation, five chemical, five physical, and one soil texture variable showed significant effects on the genetic structure and distribution of P. zhennan populations. Compared to nSSR, the genetic differentiation among populations based on cpSSR datasets conformed to the geographic isolation model, suggesting that geographic and genetic distances should be considered for further genetic conservation and breeding utilization. The importance of in situ conservation units, such as populations with a high level of genetic diversity, more private alleles, and haplotypes (e.g., population SCGTS, SCYFS, and YNYJX), should be emphasized. Additionally, breeding, along with artificially assisted population regeneration and restoration, should also be carefully planned, taking into account climate and soil properties at the same time. Conclusions In conclusion, this study provided genetic background information for the genetic conservation, management, and utilization of P. zhennan .

Background: Phoebe zhennan and Phoebe chekiangensis are valuable evergreen trees recognized for their unique aromas and ecological significance, yet the organ-related distribution and functional implications of aroma-active volatiles remain insufficiently characterized. Methods: In this study, we applied an integrated GC-MS-based volatile metabolomics approach combined with a relative odor activity value (rOAV) analysis to comprehensively profile and compare the volatile metabolite landscape in the seeds and leaves of both species. Results: In total, 1666 volatile compounds were putatively identified, of which 540 were inferred as key aroma-active contributors based on the rOAV analysis. A multivariate statistical analysis revealed clear tissue-related separation: the seeds were enriched in sweet, floral, and fruity volatiles, whereas the leaves contained higher levels of green leaf volatiles and terpenoids associated with ecological defense. KEGG pathway enrichment indicated that terpenoid backbone and phenylpropanoid biosynthesis pathways played major roles in shaping these divergent profiles. A Venn diagram analysis further uncovered core and unique volatiles underlying species and tissue specificity. Conclusions: These insights provide an integrated reference for understanding tissue-divergent volatile profiles in Phoebe species and offer a basis for fragrance-oriented selection, ecological trait evaluation, and the sustainable utilization of organ-related metabolic characteristics in breeding and conservation programs.

To assess the impacts of ozone (O ) on carbon metabolism of subtropical broadleaved tree species, seedlings of and were exposed to elevated O levels in open-top chambers (OTCs) from June to November 2014. Three treatments were conducted in nine total OTCs, including charcoal-filter air (CF) as a control treatment, low O treatment 'O3-1' (∼100 nl l ), and high O treatment 'O3-2' (∼150 nl l ). Our findings demonstrated that elevated O levels significantly decreased the net photosynthesis rates ( ) and leaf, root, and total biomass of both species, while it did not significantly affect the root/shoot ratio in and . O3-1 treatments significantly increased water soluble carbohydrates (WSC) in leaves of both tree species, while only increased the total non-structural carbohydrates (TNC) and starch in leaves of ; effects on were equivalent in comparison to the control treatment (CF). Likewise, there was no effect of treatment on the polysaccharide content of both tree species. The contents of polysaccharide, starch contents in fine roots of both species, and TNC in fine roots of increased significantly in O3-1 compared to CF. O3-2 treatment significantly decreased starch and TNC in the fine roots of , and significantly decreased polysaccharide, starch, WSC, and TNC in the fine roots of . Elevated O had no effects on leaf polysaccharide in both species, but O3-1 significantly increased polysaccharide in the fine roots of both species, and O3-1 significantly increased WSC in the leaves while decreased that in the fine roots of both species. These results suggested that elevated O levels have significant impacts on the carbon metabolism of both tree species in our study, with differential responses between tree species and among leaves and roots.