{"title":"Drought inhibits thermomorphogenesis via salicylic acid-mediated suppression of ELF3 phase separation","authors":"Ruitian Song, Mande Xue, Huairen Zhang, Xiaoyi Li, Hui Li, Danhua Jiang","doi":"10.1111/tpj.70466","DOIUrl":"https://doi.org/10.1111/tpj.70466","url":null,"abstract":"<div>\u0000 \u0000 <p>Plants are constantly exposed to environmental changes and must respond carefully to ensure survival and growth. Under high temperatures, many plants exhibit a series of morphological and developmental adjustments, including increased hypocotyl and petiole elongation. These adaptations, collectively termed thermomorphogenesis, promote transpiration and water loss, thereby enhancing evaporative cooling. However, this phenomenon has primarily been described under well-watered conditions, whereas in nature, heat often coincides with other environmental challenges, such as drought. How thermomorphogenesis integrates with water shortage conditions, where excess water loss can be detrimental, remains unclear. Here, we demonstrate that restricting water availability and mimicking drought stress with mannitol or PEG inhibit thermomorphogenesis. Mechanistically, both mannitol and PEG treatments reduce high temperature-induced transcriptional activation of <i>PHYTOCHROME INTERACTING FACTOR 4</i> (<i>PIF4</i>), a central regulator of thermomorphogenesis. This suppression is contributed to by the enhanced production of plant phytohormone salicylic acid (SA), which disrupts phase separation and prevents the deactivation of EARLY FLOWERING 3 (ELF3), a repressor of <i>PIF4</i>, at high temperatures, thereby inhibiting <i>PIF4</i> activation. Our study highlights the trade-off between cooling at high temperatures and minimizing excessive water loss under water-limited conditions, providing insights into plant responses to complex environmental challenges.</p>\u0000 </div>","PeriodicalId":233,"journal":{"name":"The Plant Journal","volume":"123 5","pages":""},"PeriodicalIF":5.7,"publicationDate":"2025-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144999110","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiangbin Chen, Ying Li, Muhammad Redzuan Bin Jamil, Jolly Madathiparambil Saju, Rajani Sarojam, Nam-Hai Chua
{"title":"Salicylic acid reduces ELF3 phase separation and suppresses thermomorphogenic growth in Arabidopsis","authors":"Xiangbin Chen, Ying Li, Muhammad Redzuan Bin Jamil, Jolly Madathiparambil Saju, Rajani Sarojam, Nam-Hai Chua","doi":"10.1111/tpj.70335","DOIUrl":"https://doi.org/10.1111/tpj.70335","url":null,"abstract":"<div>\u0000 \u0000 <p>Salicylic acid (SA), a long-characterized defense hormone, is increasingly recognized for its roles in plant growth and development. However, its involvement in mediating plant growth responses to environmental cues remains less understood. Here, we show that SA negatively affects thermomorphogenic growth in <i>Arabidopsis thaliana</i>. SA levels decrease in Arabidopsis when exposed to warm temperatures (29°C). Seedlings treated with exogenous SA, as well as transgenic plants with elevated SA levels, exhibit significantly reduced thermoresponsive hypocotyl elongation compared with control seedlings. By contrast, SA-deficient mutant seedlings display enhanced elongation. SA significantly decreases warmth-induced expression of <i>PHYTOCHROME-INTERACTING FACTOR 4</i> (<i>PIF4</i>), a central regulator of thermomorphogenesis, and of downstream auxin biosynthesis and signaling genes. Furthermore, the inhibitory effects of SA on thermomorphogenic growth and warmth-induced <i>PIF4</i> expression are largely dependent on <i>EARLY FLOWERING 3</i> (<i>ELF3</i>). SA reduces liquid-liquid phase separation (LLPS) of ELF3 prion-like domain (ELF3-Prd) <i>in vitro</i>, although the underlying mechanism remains to be elucidated. Correspondingly, elevated SA levels in plants decrease ELF3 nuclear speckle formation and enhance ELF3 binding to the <i>PIF4</i> promoter at warm temperatures, whereas reduced SA levels in plants lead to the opposite effect. Collectively, our study uncovers a previously unrecognized role of SA in plant growth adaptation to the changing climate.</p>\u0000 </div>","PeriodicalId":233,"journal":{"name":"The Plant Journal","volume":"123 5","pages":""},"PeriodicalIF":5.7,"publicationDate":"2025-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144998813","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiaoche Wang, Zhiwen Yu, Xiang Li, Jiahao Lu, Ying Tang, Fengcheng Li, Hai Xu, Wenfu Chen, Quan Xu
{"title":"JMJ720 encodes an H3K9me2 demethylase that regulates grain size in rice","authors":"Xiaoche Wang, Zhiwen Yu, Xiang Li, Jiahao Lu, Ying Tang, Fengcheng Li, Hai Xu, Wenfu Chen, Quan Xu","doi":"10.1111/tpj.70462","DOIUrl":"https://doi.org/10.1111/tpj.70462","url":null,"abstract":"<div>\u0000 \u0000 <p>Grain size is a crucial determinant of rice yield, yet the molecular mechanisms controlling this trait remain only partially understood. Here, we identified the <i>JMJ720</i> locus as a key regulator of grain size through map-based cloning. The <i>jmj720</i> mutant was found to exhibit significantly larger grains when compared to the wild type (WT). <i>JMJ720</i> encodes a protein with a Jumonji C (JmjC) domain that serves as a histone H3K9me2 demethylase. In this study, we found that JMJ720 decreases the methylation level of H3K9me2 at the <i>OsNDB2</i> locus, which codes for a putative rotenone-insensitive type II NAD(P)H dehydrogenase, thereby promoting <i>OsNDB2</i> expression. Elevated expression of <i>OsNDB2</i> was associated with reduced grain size, whereas increased H3K9me2 methylation at the <i>OsNDB2</i> locus in the <i>jmj720</i> mutant led to the repression of its expression, resulting in larger grain size. These findings unveil a novel epigenetic mechanism by which a JmjC-domain protein regulates grain size and offer a potential strategy for breeding rice varieties with enhanced grain size and yield.</p>\u0000 </div>","PeriodicalId":233,"journal":{"name":"The Plant Journal","volume":"123 5","pages":""},"PeriodicalIF":5.7,"publicationDate":"2025-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145005604","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Association of the PWWP-domain protein HUA2 and the H3K36 methylation in flowering time control","authors":"Qingxuan Xie, Zepeng Li, Wei Zhao, Aiwu Dong, Ying Ruan, Wen-Hui Shen","doi":"10.1111/tpj.70461","DOIUrl":"https://doi.org/10.1111/tpj.70461","url":null,"abstract":"<div>\u0000 \u0000 <p>Trimethylation of histone H3 at lys36 (H3K36me3) promotes gene transcription and governs plant development and plant responses to environmental cues. Yet, how H3K36me3 is translated into specific downstream events remains largely uninvestigated. Here, we report that the Arabidopsis PWWP-domain protein HUA2 binds methyl-H3K36 in a PWWP motif-dependent manner. Mutations of the PWWP motif impeded <i>HUA2</i> function to successfully rescue the <i>hua2-7</i> mutant phenotype. Genetic interaction analysis revealed that <i>HUA2</i> is hypostatic to the H3K36-methyltransferase gene <i>SDG8</i>, albeit both <i>hua2-7</i> and <i>sdg8-1</i> mutants display early-flowering phenotypes under long-day, medium-day, or short-day photoperiod. The mutant early-flowering phenotypes were found primarily associated with the reductions of expression of the transcriptional repressor genes <i>FLC</i> and <i>MAF1</i>. Chromatin immunoprecipitation revealed that H3K36me3 levels at <i>FLC</i> and <i>MAF1</i> are <i>SDG8</i>-dependent but not <i>HUA2</i>-dependent. In contrast, histone acetylation (H3ac, H3K9ac) levels at <i>FLC</i> and <i>MAF1</i> were found reduced in <i>hua2-7</i> and the reductions were largely <i>SDG8</i>-dependent. Collectively, our results suggest that HUA2 functions as a H3K36me3 reader to promote H3ac/H3K9ac in the transcriptional activation of <i>FLC</i> and <i>MAF1</i> to prevent precocious plant flowering.</p>\u0000 </div>","PeriodicalId":233,"journal":{"name":"The Plant Journal","volume":"123 5","pages":""},"PeriodicalIF":5.7,"publicationDate":"2025-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145005605","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Cooperative contribution of multiple energy substrate pathways to floral thermogenesis in sacred lotus","authors":"Miao Yu, Ruohan Wang","doi":"10.1111/tpj.70460","DOIUrl":"https://doi.org/10.1111/tpj.70460","url":null,"abstract":"<div>\u0000 \u0000 <p>Floral thermogenesis in lotus (<i>Nelumbo nucifera</i>) is a highly energy-intensive process, requiring substantial metabolic reconfiguration and substrate input. However, the mechanisms coordinating energy substrate supply during this process remain unclear. Here, we integrated microscale proteomics, time-series transcriptomics, and mitochondrial feeding assays to elucidate the substrate provisioning strategies supporting thermogenesis in lotus receptacles. Proteomic analysis revealed a concerted upregulation of major energy metabolism pathways at the thermogenic initiation stage, accompanied by enhanced expression of energy dissipation-related proteins (alternative oxidase and uncoupling proteins), indicative of a metabolic shift favoring heat production over ATP synthesis. Our results highlight the cooperative contribution of multiple pyruvate sources to mitochondrial respiration. Both the mitochondrial pyruvate carrier (MPC)-mediated cytosolic pyruvate import and the NAD-dependent malic enzyme (NAD-ME)-derived intramitochondrial pyruvate flux were significantly elevated at the thermogenic stage. Notably, isotopic feeding experiments revealed that NAD-ME-derived pyruvate may contribute more substantially than MPC-derived pyruvate under thermogenic conditions, reflecting a highly flexible substrate utilization strategy. In addition, increased expression of alanine aminotransferase (AlaAT) and β-oxidation-related genes suggested that alanine transamination and fatty acid degradation may further expand the respiratory substrate pool. Collectively, this study uncovers a diverse and dynamic landscape of energy substrate supply that underpins heat production in thermogenic lotus tissues. These findings offer insights into how plants coordinate metabolic flexibility to meet the high energetic demands of floral thermogenesis.</p>\u0000 </div>","PeriodicalId":233,"journal":{"name":"The Plant Journal","volume":"123 5","pages":""},"PeriodicalIF":5.7,"publicationDate":"2025-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144998948","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Maryam Nasr Esfahani, Lisa Koch, Jörg Hofmann, Sophia Sonnewald, Uwe Sonnewald
{"title":"Organ-specific transcriptional and metabolic adaptations of potato plants to limited phosphate availability prior and after tuberization","authors":"Maryam Nasr Esfahani, Lisa Koch, Jörg Hofmann, Sophia Sonnewald, Uwe Sonnewald","doi":"10.1111/tpj.70445","DOIUrl":"https://doi.org/10.1111/tpj.70445","url":null,"abstract":"<p>While plants adapt to fluctuating phosphorus (P) availability in soils by enhancing phosphate acquisition or optimizing internal P-utilization, the spatiotemporal dynamics of these responses, particularly in crops, remain poorly understood. This study systematically investigated how and when potato organs respond to fluctuating P availability across different developmental stages using transcriptomic, metabolomic, and physiological analyses of leaves, roots, and tubers. Transcriptomic data revealed dynamic, organ- and stage-specific responses to P-deficiency, with the highest number of differentially expressed genes in leaves before tuberization and in roots during tuberization. P-deficiency led to a marked accumulation of proline in tubers and nitrogen-rich amino acids, particularly glutamine and asparagine, in roots and leaves. Carbohydrate metabolism exhibited severity- and time-dependent changes: severe P-deficiency triggered earlier, stronger, but transient carbohydrate accumulation, whereas medium P-deficiency led to a gradual and sustained increase in leaves and roots. Hexose phosphates and organic acids accumulated in roots under P-stress, especially severe P-stress, during early vegetative growth, followed by a marked reduction during tuberization. During tuber filling, severe P-deficiency reduced sucrose and starch in roots, decreased leaf starch but increased leaf sucrose, likely due to impaired translocation, and a decrease in tuber sucrose alongside increased starch due to reduced degradation. Under medium P-deficiency, sucrose and starch remained stable in leaves and tubers but declined in roots, reflecting a moderate shift in carbon allocation that maintained tuber development at the expense of root metabolism. These findings highlight the spatiotemporal regulation of metabolic and molecular responses to P-deficiency in potato and provide insights for improving nutrient use efficiency and stress resilience in crops.</p>","PeriodicalId":233,"journal":{"name":"The Plant Journal","volume":"123 5","pages":""},"PeriodicalIF":5.7,"publicationDate":"2025-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/tpj.70445","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144999040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Gabriel Rennato Hassinger-Lino, Luis Bolaños, José María García-Mina, Ángel María Zamarreño, Cristina Nieto, María Reguera
{"title":"Boron Toxicity Modulates Hypocotyl Growth Through Brassinosteroid and Thermomorphogenic-Like Mechanisms.","authors":"Gabriel Rennato Hassinger-Lino, Luis Bolaños, José María García-Mina, Ángel María Zamarreño, Cristina Nieto, María Reguera","doi":"10.1111/pce.70173","DOIUrl":"https://doi.org/10.1111/pce.70173","url":null,"abstract":"<p><p>Boron toxicity (BT) is a significant environmental stressor that negatively affects plant development, yet its molecular mechanisms remain poorly understood. Interestingly, certain toxic concentrations of boron trigger hypocotyl elongation, suggesting a complex hormonal response. In this study, we focus on the role of brassinosteroids (BRs) in mediating this atypical growth. Our findings demonstrate that BT stimulates BR biosynthesis while simultaneously suppressing its inactivation, resulting in sustained BR activity throughout seedling development. Furthermore, we provide evidence that BT disrupts the normal BR negative feedback regulation, potentially converting it into a positive feedback mechanism that amplifies the elongation response. We also show that this response shares mechanistic similarities with thermomorphogenesis, particularly in its reliance on COP1, PIF4, and BR signalling pathways. Loss-of-function mutants of COP1 and PIF4 exhibited reduced hypocotyl elongation, underscoring their essential roles in this process. Although further research is needed to fully clarify the molecular details, our work reveals a previously unrecognised connection between BT responses and thermomorphogenic growth. We also propose a working model to better understand how BR signalling contributes to plant adaptation under BT stress conditions.</p>","PeriodicalId":222,"journal":{"name":"Plant, Cell & Environment","volume":" ","pages":""},"PeriodicalIF":6.3,"publicationDate":"2025-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144999297","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Prakitchai Chotewutmontri, Rosalind Williams-Carrier, Susan Belcher, Alice Barkan
{"title":"Effects of light on chloroplast translation in Marchantia polymorpha are similar to those in angiosperms and are not influenced by light-independent chlorophyll synthesis","authors":"Prakitchai Chotewutmontri, Rosalind Williams-Carrier, Susan Belcher, Alice Barkan","doi":"10.1111/tpj.70458","DOIUrl":"https://doi.org/10.1111/tpj.70458","url":null,"abstract":"<p>Translation of the chloroplast <i>psbA</i> mRNA in angiosperms is activated by photodamage of its gene product, the D1 subunit of photosystem II (PSII), providing nascent D1 for PSII repair. The involvement of chlorophyll in the regulatory mechanism has been suggested due to the regulatory roles of proteins proposed to mediate chlorophyll/D1 transactions and the fact that chlorophyll is synthesized only in the light in angiosperms. We used ribosome profiling and RNA-seq to address whether the effects of light on chloroplast translation are conserved in the liverwort Marchantia (<i>Marchantia polymorpha</i>), which synthesizes chlorophyll in both the dark and the light. As in angiosperms, ribosome occupancy on <i>psbA</i> mRNA decreased rapidly upon shifting plants to the dark and was rapidly restored upon a transfer back to the light, whereas ribosome occupancy on other chloroplast mRNAs changed very little. The results were similar in a <i>Marchantia</i> mutant unable to synthesize chlorophyll in the dark. Those results, in conjunction with pulse-labeling data, suggest that light elicits a plastome-wide activation of translation elongation and a specific increase in <i>psbA</i> translation initiation in <i>Marchantia</i>, as in angiosperms. These findings show that light regulates chloroplast translation similarly in vascular and non-vascular plants, and that constitutive chlorophyll synthesis does not affect light-regulated <i>psbA</i> translation initiation. Additionally, the translational outputs of chloroplast genes are similar in <i>Marchantia</i> and angiosperms but result from differing contributions of mRNA abundance and translational efficiencies. This adds to the evidence that chloroplast mRNA abundance and translational efficiencies co-evolve under selection to maintain protein outputs.</p>","PeriodicalId":233,"journal":{"name":"The Plant Journal","volume":"123 5","pages":""},"PeriodicalIF":5.7,"publicationDate":"2025-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/tpj.70458","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144999013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rebecca Leuschen-Kohl, Robyn Roberts, Danielle M Stevens, Ning Zhang, Silas Buchanan, Brooke Pilkey, Gitta Coaker, Anjali S Iyer-Pascuzzi
{"title":"Tomato Roots Exhibit Development-Specific Responses to Bacterial-Derived Peptides.","authors":"Rebecca Leuschen-Kohl, Robyn Roberts, Danielle M Stevens, Ning Zhang, Silas Buchanan, Brooke Pilkey, Gitta Coaker, Anjali S Iyer-Pascuzzi","doi":"10.1111/pce.70164","DOIUrl":"10.1111/pce.70164","url":null,"abstract":"<p><p>To combat soilborne pathogens, roots activate pattern-triggered immunity (PTI) through pattern-recognition receptors (PRRs) that recognise microbe-associated molecular patterns (MAMPs). Root PTI pathways can differ from their above-ground counterparts and have been well-characterised in the model plant Arabidopsis thaliana but are not well-defined in crops. Gene repurposing coupled with differences in root tissues and root architecture in tomato species (Solanum lycopersicum and S. pimpinellifolium) led us to hypothesise that signalling pathways of Solanaceous-specific PRRs diverge from canonical pathways. The objective of this study was to characterise PTI signalling pathways and responses (ROS, MAPK, gene expression, and growth inhibition) in roots of wild and domesticated tomatoes downstream of three immune receptors: the well-conserved SlFLS2 and the Solanaeceous-specific FLS3 and CORE. We find that Solanum root PTI responses are concentrated in early differentiating root regions compared to late differentiating regions or whole roots, and that FLS3 and CORE signalling pathways are overlapping but distinct from each other and from FLS2. Although the early differentiating root region had strong PTI responses across Solanum cultivars and species, different genetic backgrounds varied in their response dynamics. Our results underscore the complexity of PTI signalling across species and highlight the developmental-stage specificity of tomato root immunity.</p>","PeriodicalId":222,"journal":{"name":"Plant, Cell & Environment","volume":" ","pages":""},"PeriodicalIF":6.3,"publicationDate":"2025-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144999375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Boaz Hilman, Emily F Solly, Frank Hagedorn, Iris Kuhlman, David Herrera-Ramírez, Susan Trumbore
{"title":"<sup>14</sup>C-Age of Carbon Used to Grow Fine Roots Reflects Tree Carbon Status.","authors":"Boaz Hilman, Emily F Solly, Frank Hagedorn, Iris Kuhlman, David Herrera-Ramírez, Susan Trumbore","doi":"10.1111/pce.70154","DOIUrl":"https://doi.org/10.1111/pce.70154","url":null,"abstract":"<p><p>The time elapsed between carbon fixation into nonstructural carbohydrates (NSC) and their use to grow tree structural tissues can be estimated by <sup>14</sup>C ages. Reported <sup>14</sup>C-ages indicate that NSC used to grow root tissues (growth NSC) can vary from < 1 year to decades. To understand the controls of this variability, we compared <sup>14</sup>C-ages of leaf, branch, and root tissues from two conifers (Larix decidua, Pinus mugo) in a control valley site and an alpine treeline ecotone where low temperatures restrict tree growth. Our results of increasing respiration rate and NSC concentration with ecotone elevation suggest an excess of C assimilation over growth and an increase in fresh NSC supply. Greater flow of fresh NSC through needles and branches could explain their young growth NSC (< 2 years). A smaller inflow of fresh NSC into roots could explain older growth NSC ages, which increased from 2 to 10 years from the valley to the bottom of the ecotone, and then declined to 6 years at the ecotone top. Rather than species differences that were small, environmental conditions over years appear to be the primary driver of C allocation dynamics, which are reflected in the <sup>14</sup>C-ages of fine roots.</p>","PeriodicalId":222,"journal":{"name":"Plant, Cell & Environment","volume":" ","pages":""},"PeriodicalIF":6.3,"publicationDate":"2025-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144999343","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}