Tree physiology最新文献

{"title":"Photoperiod does not affect thermal acclimation of shoot-scale gas exchange but is important for shoot development in cuttings of Norway spruce (Picea abies (L.) H. Karst).","authors":"Astrid Fridell, Göran Wallin, Curt Almqvist, Lasse Tarvainen","doi":"10.1093/treephys/tpaf112","DOIUrl":"https://doi.org/10.1093/treephys/tpaf112","url":null,"abstract":"<p><p>The growth of boreal trees is expected to benefit from increasing global temperatures through enhanced photosynthetic rates and longer growing seasons. However, since photoperiod is independent of climate change, it may limit the expected growth benefits from a longer growing season and could thus constrain boreal trees' physiological responses to warming. We carried out a growth chamber experiment on two-year-old Norway spruce (Picea abies) cuttings from two latitudinal origins to investigate the interaction between day length (20/4 hours vs 14/10 hours light/dark) and enhanced temperatures (25/20 °C vs 15/10 °C day/night) on height growth, bud development and shoot-scale gas exchange. Height growth was greater under longer day length while bud development occurred faster both under longer day length and higher growth temperature. Growth temperature did not have a significant effect on the light-saturated photosynthetic rate but higher growth temperature resulted in lower dark respiration rate. Cuttings in the low growth temperature treatment exhibited higher apparent quantum yields indicating that lower growth temperature benefited net carbon uptake under low light availability, such as the conditions experienced by seedlings growing in the forest understory. Day length did not influence the thermal acclimation of shoot-scale gas exchange. The two populations from different origins did not differ in the measured parameters, except for a higher dark respiration rate in the high latitude cuttings. Overall, while day length did not affect the thermal acclimation of photosynthetic processes, it appears to constrain height growth and bud development, thereby reducing the potential performance benefit of a warming-induced lengthening of the growing season.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145092451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Boron reduces the damage of copper toxicity to Citrus sinensis cell wall structure and function via maintaining copper, calcium, magnesium, potassium, and phosphorus homeostasis in subcellular fractions.","authors":"Xu-Feng Chen, Wei-Lin Huang, Liang-Yuan Tong, Tian-Tian Xia, Ti Wu, Fei Lu, Jiuxin Guo, Zeng-Rong Huang, Lin-Tong Yang, Li-Song Chen","doi":"10.1093/treephys/tpaf114","DOIUrl":"https://doi.org/10.1093/treephys/tpaf114","url":null,"abstract":"<p><p>Commercial citrus are predominantly grown in acidic soils with low boron (B) and high copper (Cu) concentrations. There are limited data on how B-Cu treatments affect the concentrations and distributions of nutrients in leaf and root subcellular fractions. Citrus sinensis seedlings were exposed to 2.5 (B2.5) or 25 (B25) μM H3BO3 × 0.5 (Cu0.5) or 350 (Cu350) μM CuCl2 for 24 weeks. Thereafter, we assayed the concentrations of Cu, calcium, magnesium, potassium, and phosphorus in leaf and root cell wall (CW) fraction, organelle fraction, and soluble fraction, as well as the expression levels of genes related to their homeostasis. B25 reduced Cu350-induced damage of CW structure and function via alleviating Cu350-induced increment in the Cu concentration and decrements in the calcium, magnesium, potassium, and phosphorus concentrations, as well as Cu350-induced alterations of their distributions in root and leaf subcellular fractions, thereby promoting seedling growth. Also, leaves and roots of B2.5-treated seedlings displayed some adaptive responses to Cu350. Cu350 increased the distribution of Cu in CW fraction to prevent it from entering more sensitive targets; and the distributions of calcium, magnesium, and potassium in CW fraction to maintain CW structure and function. However, Cu350 decreased the distribution of phosphorus in CW fraction, but increased the release of phosphate from organic-phosphate compounds and the conversion of pyrophosphate into phosphate to maintain phosphate homeostasis. Therefore, the study provided novel evidence for B to alleviate Cu toxicity in citrus via maintaining the Cu, calcium, magnesium, potassium, and phosphorus homeostasis in subcellular fractions and a scientific basis for the rational application of calcium, magnesium, potassium, and phosphorus fertilizers in woody crops (citrus) to prevent Cu toxicity.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145092429","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Phenological patterns and factors affecting the lifespan of fine roots in forests.","authors":"Jiawen Hou, M Luke McCormack, Gregoire T Freschet, Peter B Reich, Hans Lambers, Fuqiang Long, Tao Sun","doi":"10.1093/treephys/tpaf106","DOIUrl":"https://doi.org/10.1093/treephys/tpaf106","url":null,"abstract":"<p><p>The phenology and lifespan of fine roots influence plant resource acquisition and fine-root carbon fluxes into soil, yet the extent to which fine-root phenology and lifespan vary across species and plant functional types, as well as the underlying drivers of this variation, remain poorly understood. We observed fine-root lifespan, production and mortality dynamics in 11 temperate forest species for two consecutive years using minirhizotrons, and measured leaf lifespan. We tested the influence of environmental factors on fine-root dynamics and determined whether traits affecting lifespan differed among leaves and roots. Peak fine-root production mainly occurred in early summer followed by the peak of fine root mortality, occurring mainly in late summer. The median fine root lifespan (MRL) was negatively and positively associated with root nitrogen concentration and root diameter, respectively. In contrast, the best predictors of leaf lifespan (LL) were leaf tissue density and specific leaf area. MRL and LL were not related. Our results highlight that, although leaves and fine roots were partly influenced by the same trade-off between high metabolism and long lifespan, MRL is largely non-coordinated with LL, suggesting temporally decoupled ecological strategies above and belowground for maintaining functional resource-acquisition organs. Furthermore, species-specific patterns of root production suggest variable strategies among species to enhance resource acquisition. Such differences also imply variable influences of species on carbon dynamics in temperate forests.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145087574","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Targeting histone acetylation to enhance somatic embryogenesis in Quercus suber L.","authors":"Natalia E Paz, Elena Carneros, Beatriz Pintos, Pilar S Testillano","doi":"10.1093/treephys/tpaf111","DOIUrl":"https://doi.org/10.1093/treephys/tpaf111","url":null,"abstract":"<p><p>Somatic embryogenesis (SE) is an in vitro mass propagation system widely employed in plant breeding programs. However, its efficiency in many forest species remains limited due to their recalcitrance. SE relies on the induction of somatic cell reprogramming into embryogenic pathways, a process influenced by transcriptomic changes regulated, among other factors, by epigenetic modifications such as DNA methylation, histone methylation, and histone acetylation. Despite its relevance, epigenetic regulation of SE in forest species is not well understood. In this study, we analyzed histone H4 acetylation during SE in cork oak (Quercus suber) and evaluated the effects of suberoylanilide hydroxamic acid (SAHA), a histone deacetylase (HDAC) inhibitor, scarcely used in plants, on the process. Histone H4 acetylation levels progressively increased after SE induction, correlating with enhanced histone acetyl transferase (HAT) enzymatic activity. HAT gene QsHAM1-like was activated in developing somatic embryos, while HDAC genes QsHDA9, QsHDA19, QsHDA15 and QsHDA2 showed similar expression patterns among them, and opposite profiles to QsHAM1-like HAT gene, suggesting a coordinated interplay of HAT and HDAC activities in modulating global H4 acetylation during SE. SAHA treatment elevated histone H4 acetylation, promoted embryogenic mass proliferation, and induced the expression of QsSERK1-like, an early SE marker. While continuous SAHA exposure inhibited embryo differentiation, its removal restored embryo development, significantly increasing somatic embryo production. Inhibition of HAT activity by butyrolactone 3 (MB-3) decreased histone acetylation levels and reduced somatic embryo formation, providing further evidence that histone acetylation is essential for SE development. These findings highlight the critical role of histone acetylation in the SE of forest trees and propose transient treatments with epigenetic modulators like SAHA as a promising strategy to enhance somatic embryo production in recalcitrant forest species.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145024315","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Divergent leaf water strategies in three coexisting desert shrub species: from the perspective of hydraulic, stomatal, and economic traits.","authors":"Wenyue Zhao, Xibin Ji, Rui Chen, Zeyu Du, Bowen Jin, Hai Zhou, Liwen Zhao, Dongsheng Li","doi":"10.1093/treephys/tpaf110","DOIUrl":"https://doi.org/10.1093/treephys/tpaf110","url":null,"abstract":"<p><p>Leaves constitute a vital bottleneck in whole-plant water transport, and their water strategies are key determinants of plant competition and productivity. Nonetheless, our knowledge of leaf water strategies predominantly stems from single perspectives (i.e., hydraulic, stomatal, or economic traits), severely limiting our capacity to comprehensively predict plant vulnerability and sustainability, especially under drought-stress conditions. Here, we examined the leaf hydraulic, stomatal, and economic traits of three coexisting shrub species (i.e., Haloxylon ammodendron, Calligonum mongolicum, and Nitraria sphaerocarpa) in the Badain Jaran desert-oasis ecotone to comprehensively evaluate their water strategies and drought adaptation mechanisms. The results demonstrated that these three shrubs exhibited significant differences in leaf hydraulic vulnerability, osmoregulatory capacity, stomatal behavior, and economic traits. Nonetheless, these traits remain tightly related to guarantee their survival. Interestingly, two distinct interaction mechanisms between stomatal and hydraulic regulation were identified among the three shrubs with varying stomatal sensitivity. Specifically, N. sphaerocarpa and H. ammodendron employed relatively lower isohydric stomatal behavior, characterized by a synergistic decrease in vapor-phase water loss as liquid-phase water transport decreased during severe atmospheric drought. Conversely, C. mongolicum adopted higher isohydric stomatal behavior, rapidly reducing vapor-phase water loss during initial drought stress to compensate for its more vulnerable liquid-phase water transport system. Notably, all three shrubs presented risky leaf water strategies with negative hydraulic safety margins. Among them, the hydraulic dysfunction risk was lowest for C. mongolicum, followed by N. sphaerocarpa and H. ammodendron. Overall, our findings are anticipated to offer valuable insights for afforestation initiatives and ecological conservation efforts in desert-oasis ecotones that function as critical shelterbelts.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145006654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Acclimation of mango (Mangifera indica cv. Calypso) to canopy light gradients - scaling from leaf to canopy.","authors":"Alexander W Cheesman, Kali B Middleby, Ryan Orr, Liqi Han, Gerhard Rossouw, Lucas A Cernusak","doi":"10.1093/treephys/tpaf109","DOIUrl":"https://doi.org/10.1093/treephys/tpaf109","url":null,"abstract":"<p><p>Mango (Mangifera indica), a leading tropical fruit crop, is a prime candidate for intensification through modern orchard-management techniques, including canopy manipulation to improve light interception. This study investigated how leaf-level acclimation to light gradients within the canopy of a high-yield, dwarfing mango cultivar (Calypso™) could be used to examine integrated canopy-scale responses. We quantified foliar morphological, biochemical, and physiological traits across a range of canopy positions using this information to model canopy-scale productivity within digital-twin representations of mango under both conventional (i.e. open-vase) and espalier training canopy systems. Key findings demonstrated that leaves exposed to higher light exhibited increased leaf mass per unit area (LMA), nitrogen content, and photosynthetic capacity (Asat), but decreased chlorophyll-to-nitrogen ratios and photochemical reflectance indices, reflecting trade-offs between light capture and photoprotection. Phenolic content increased under high irradiance, indicating investment in photoprotective compounds at the expense of net carbon gain. Modelled leaf-level productivity increased with light availability, following a Michaelis-Menten saturating response, with diminishing returns under high light. Digital modelling of canopy light interception revealed that espalier-trellis training enhanced light distribution efficiency per unit leaf area but resulted in a 6.5% reduction in total canopy productivity due to a smaller total canopy leaf area. However, when normalized by total canopy leaf area, the espalier-trellis system showed a 3.6% productivity advantage over conventional canopies at the time of year modelled. These results highlight the role of canopy structure and light-use efficiency play in determining orchard productivity. Integrating spatially explicit mechanistic models with LiDAR-derived canopy data offers a promising pathway for designing high-density, resource-efficient mango orchards. Future work should expand modelling to account for dynamic canopy shape throughout the growing season and evaluate the interaction of modified canopy structures with environmental stressors, particularly under climate variability.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145001117","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tracking subtle seasonal shifts in pigment composition with hyperspectral reflectance in a temperate evergreen forest.","authors":"Troy S Magney, Logan E G Brissette, Zoe Amie Pierrat, Barry Logan, Jaret Reblin, Sara Nelson, Jochen Stutz, Christian Frankenberg, David R Bowling, Christopher Y S Wong","doi":"10.1093/treephys/tpaf108","DOIUrl":"https://doi.org/10.1093/treephys/tpaf108","url":null,"abstract":"<p><p>Pigment dynamics in temperate evergreen forests remain poorly characterized, despite their year-round photosynthetic activity and importance for carbon cycling. Developing rapid, nondestructive methods to estimate pigment composition enables high-throughput assessment of plant acclimation states. In this study, we investigate the seasonality of eight chlorophyll and carotenoid pigments and hyperspectral reflectance data collected at both the needle (400-2400 nm) and canopy (420-850 nm) scales in Pinus palustris (longleaf pine) at the Ordway Swisher Biological Station in north-central Florida, USA. Needle spectra were obtained at three distinct times throughout the year, while tower-based spectra were collected continuously over a nine-month period. Seasonal trends in photoprotective pigments (e.g., lutein and xanthophylls) and photosynthetic pigments (e.g., chlorophylls) aligned closely with seasonal changes in photosynthetically active radiation and gross primary productivity. To track inter-tree and seasonal variability in pigment pools with hyperspectral reflectance data, we used correlation analyses and ridge regression models. Ridge regression models using the full hyperspectral range outperformed predictions using standard linear regression with specific wavelengths in a normalized difference index fashion. Ridge regression successfully predicted all pigment pools (R2 > 0.5) with comparable accuracy at both the needle and canopy scales. The models performed best for lutein, neoxanthin, antheraxanthin, and chlorophyll a and b - which had greater inter-tree and seasonal variation - and achieved moderate accuracy for violaxanthin, alpha-carotene, and beta-carotene. These results provide a foundation for scaling biochemical traits from ground-based sensors to airborne and satellite platforms, particularly in ecosystems with subtle changes in pigment dynamics.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145001108","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Determining the mechanisms that cause woody plants to moderate microclimate in grasslands.","authors":"L K Neumann, C A Davis, S D Fuhlendorf","doi":"10.1093/treephys/tpaf107","DOIUrl":"https://doi.org/10.1093/treephys/tpaf107","url":null,"abstract":"<p><p>Forests and grasslands experience shifts in woody plant cover creating a continuum of woody plants across space. Global change accelerates this, causing many ecosystems to experience the redistribution of woody plants. There is growing interest in understanding how these ecological changes influence ecosystem function including climate regulation. Research shows that woody plant expansion generally moderates microclimate but can impact regional macroclimate differently, while the loss of woody plants may lead to hotter regional macroclimates. However, the mechanisms in grasslands are largely speculative. Changes in shade, evapotranspiration, and wind associated with woody plants may drive changes in microclimate. Because changes in temperature can impact ecosystem function, it is critical that we understand the mechanisms that drive this to determine how the redistribution of woody plants impacts grassland ecosystems. Our objective was to determine the mechanisms that cause woody plants to moderate microclimate in grasslands by testing specific hypotheses that may drive how individual woody plants influence microclimate. We performed a 2 x 2 x 2 factorial experiment in a fallow field across 3 independent variables (shade, pan evaporation, and no wind) during the summer of 2023 and measured the microclimate. We analyzed the data using a linear-mixed modeling and model selection approach. We determined that the presence of shade alone best described microclimate temperature and vapor pressure deficit. During the daytime, shade moderated temperature, especially during high temperature extremes, and reduced vapor pressure deficit, while during the nighttime shade slightly increased temperature, but largely had little effect on vapor pressure deficit except during conditions with high vapor pressure deficit. Our findings show that ecosystems experiencing woody plant expansion could experience lower temperature and vapor pressure deficit, while ecosystems experiencing a loss in woody plant cover may experience higher temperature and vapor pressure deficit, which could impact ecosystem function.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145001123","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Adjustment in leaf water relations and the maintenance of mangrove seedling growth under increasing salinity.","authors":"Vanessa Negrão-Rodrigues, Mauro Brum, Karoline Chaves da Silva, Grazielle Sales Teodoro","doi":"10.1093/treephys/tpaf091","DOIUrl":"10.1093/treephys/tpaf091","url":null,"abstract":"<p><p>Mangroves are ecosystems of high ecological and economic importance, particularly due to their capacity to store high amounts of carbon and stabilize soil. However, climate change and rising sea levels are intensifying salinity levels, challenging the survival of plant mangrove species, especially seedlings. Here, we evaluated the effects of different salinity concentrations on the growth and leaf water relations of Avicennia germinans (L.) L. and Rhizophora racemosa G.Mey. seedlings. Specifically, we tested whether A. germinans, due to its broader distribution, higher salinity tolerance and salt-excreting ability, would exhibit more pronounced adjustments and greater resilience to saline stress compared with R. racemosa. To this end, we conducted a greenhouse experiment, exposing 212 11-month-old seedlings (106 of each species) previously grown in freshwater to five salinity treatments over 3 months. These seedlings were analyzed for growth, embolism resistance, leaf water potential, osmotic parameters and gas exchange. Our results showed that A. germinans exhibited greater osmotic adjustment and stomatal regulation, enabling it to maintain leaf hydration and reduce the risk of embolism under high salinity. Conversely, R. racemosa adopted a more conservative strategy, with lower osmotic adjustment and stomatal regulation capacity but a higher hydraulic safety margin. Thus, we demonstrated that these species employ distinct strategies to cope with salinity, reflecting specific adaptations to their ecological distributions and salinity tolerance. These findings contribute to understanding the adaptive responses of mangrove seedlings to varying salinity conditions, with implications for the conservation of these ecosystems under predicted climate change scenarios.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144733388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Non-structural carbohydrates constrain xylem formation of Picea crassifolia under drought year in the Qilian Mountains of Northwest China.","authors":"Quanyan Tian, Zhibin He, Shengchun Xiao, Bao Yang, Xiaomei Peng, Xiangyan Feng, Pengfei Lin, Xi Zhu, Jingjing Liu, Eugene A Vaganov, Vladimir V Shishov, Liliana V Belokopytova","doi":"10.1093/treephys/tpaf101","DOIUrl":"10.1093/treephys/tpaf101","url":null,"abstract":"<p><p>Tree xylem formation is highly dependent on non-structural carbohydrates content and microenvironments. However, it is still less well understood how the key variables regulate cambial activity and xylem formation under different environmental conditions, or the specific contribution of each variable to the number of cells in different stages of xylogenesis. Here, we monitored the xylogenesis and xylem non-structural carbohydrates dynamics of Picea crassifolia during the growing seasons of 2021 and 2022 along an altitude gradient in the Qilian Mountains. We found that the date of maximum cell production rate was about a week later in 2021 than in 2022, and that was later at 2950 and 3200 m than at 2700 m. High altitude sites developed significantly more cambial cells, driving substantially higher cell production rates. Notably, non-structural carbohydrates remained stable early in the growing season before accumulating to peak levels in 2021, whereas 2022 showed a pronounced decrease followed by recovery. The altitude-independent contrast reveals seasonal non-structural carbohydrates dynamics, as the 2022 decline connects stored carbohydrates to sustained xylem formation under drought stress. Linear mixed-effects models showed that, in 2021, cambium cells were predominantly influenced by soil water content and tree individuality, enlargement cells primarily by air temperature (AT), wall-thickening cells by both air and soil temperatures, and the rates of cell production were most significantly affected by AT, soil temperature, and tree individuality. However, in 2022, the cambium cells enlargement cells, and cell production rates were constrained by starch and soluble sugars, while the wall-thickening cells were limited primarily by soluble sugars. Our findings demonstrate that drought triggers a physiological transition from environmental to non-structural carbohydrates mediated control of xylogenesis, highlighting the critical role of carbon reserves for tree resilience in arid regions.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12482912/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144970570","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}