Tree physiology最新文献

{"title":"Auxin treatment reduces inflorescences number and delays bud development in the alternate bearing Citrus cultivar Murcott mandarin.","authors":"Dor Haim, Madhuri Pochamreddy, Adi Doron-Faigenboim, Itzahk Kamara, Giora Ben-Ari, Avi Sadka","doi":"10.1093/treephys/tpaf009","DOIUrl":"10.1093/treephys/tpaf009","url":null,"abstract":"<p><p>Specific cultivars of many commercial fruit trees undergo cycles of heavy fruit load (ON-crop) one year, followed by low fruit load (OFF-crop) the next (termed alternate bearing). Fruit load may affect flowering at various developmental stages, and its presence is suggested to generate a flowering-inhibitory signal. In a previous report, we showed that the presence of fruit induces polar auxin transport from the fruit into the stem, interfering with indole acetic acid release from the bud and thus elevating its levels in the bud meristem. To better understand the relationship between auxin homeostasis in the bud and flowering, indole acetic acid or 2,4-dichlorophenoxyacetic acid (2,4-D) was applied with the polar auxin transport blocker 2,3,5-triiodobenzoic acid to OFF-crop 'Murcott' mandarin (Citrus reticulata × Citrus sinensis) trees during the flowering-induction period. The treatment reduced inflorescence number and delayed bud development. Transcriptome analysis following the treatment revealed a reduction in the expression of a few flowering-control genes, including LEAFY and SQUAMOSA PROMOTER BINDING PROTEIN-LIKE. In addition, genes related to carbohydrate metabolism were reduced. We suggest that the elevation of auxin levels in the bud by heavy fruit load directly affects the expression of flowering-control, flower-development and developmental genes.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":"45 3","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143664638","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":"Auxin treatment reduces inflorescences number and delays bud development in the alternate bearing Citrus cultivar Murcott mandarin.","authors":"Dor Haim, Madhuri Pochamreddy, Adi Doron-Faigenboim, Itzahk Kamara, Giora Ben-Ari, Avi Sadka","doi":"10.1093/treephys/tpaf009","DOIUrl":"10.1093/treephys/tpaf009","url":null,"abstract":"<p><p>Specific cultivars of many commercial fruit trees undergo cycles of heavy fruit load (ON-crop) one year, followed by low fruit load (OFF-crop) the next (termed alternate bearing). Fruit load may affect flowering at various developmental stages, and its presence is suggested to generate a flowering-inhibitory signal. In a previous report, we showed that the presence of fruit induces polar auxin transport from the fruit into the stem, interfering with indole acetic acid release from the bud and thus elevating its levels in the bud meristem. To better understand the relationship between auxin homeostasis in the bud and flowering, indole acetic acid or 2,4-dichlorophenoxyacetic acid (2,4-D) was applied with the polar auxin transport blocker 2,3,5-triiodobenzoic acid to OFF-crop 'Murcott' mandarin (Citrus reticulata × Citrus sinensis) trees during the flowering-induction period. The treatment reduced inflorescence number and delayed bud development. Transcriptome analysis following the treatment revealed a reduction in the expression of a few flowering-control genes, including LEAFY and SQUAMOSA PROMOTER BINDING PROTEIN-LIKE. In addition, genes related to carbohydrate metabolism were reduced. We suggest that the elevation of auxin levels in the bud by heavy fruit load directly affects the expression of flowering-control, flower-development and developmental genes.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143012357","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":"Prospects for high-throughput estimates of photosynthetic parameters in tropical trees using the Dynamic Assimilation™ Technique.","authors":"Emmelia J Braun, Charles D Southwick, Maquelle N Garcia, Tyeen C Taylor, Kelvin Acebron, João Victor F C Rodrigues, Marciel J Ferreira, Raimundo C de Oliveira, Loren P Albert","doi":"10.1093/treephys/tpae153","DOIUrl":"10.1093/treephys/tpae153","url":null,"abstract":"<p><p>Amazônia is a species-rich region of immense importance to Earth's water and carbon cycling. Photosynthesis drives the global carbon cycle, so understanding photosynthetic differences across diverse landscapes is a key task of ecophysiology and ecosystem science. Unfortunately, due to physiological and logistical constraints, ground-based photosynthesis data in Amazônia remain scarce and the 'traditional' steady-state (SS) method of gas exchange is slow and inefficient. The Dynamic Assimilation™ Technique (DAT) promises a new way to perform A/Ci curves rapidly without requiring SS conditions. Thus far, this technique has only been validated in greenhouse or agricultural-field-grown species and has yet to be tested in forest trees of diverse physiology morphology and environmental adaptation. To test the utility of the DAT in a complex tropical forest ecosystem, we compared the DAT with the SS method in 13 Amazonian trees in situ. We found strong agreement between Vcmax from DAT curves and SS curves, while Jmax was underestimated in DAT curves. We conclude that the DAT provides a robust and rapid estimation of Vcmax. We also identified diverse and unexpected DAT curve shapes among some trees, including the presence of an 'overshoot' in assimilation beyond model-derived ribulose-1,5-bisphosphate (RuBP) regeneration limitations. The presence of overshoot may elucidate microclimate and species differences in RuBP regeneration rates and emphasizes the considerable importance of DAT curve protocol specifications, such as the effect of ramp rate and direction on Jmax and TPU. Overall, the DAT saved time relative to the SS method and proved to be an effective and rapid method for quantifying Vcmax in tropical trees.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":"45 3","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143664611","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":"Choosing the right signaling pathway: hormone responses to Phytophthora cinnamomi during compatible and incompatible interactions with chestnut (Castanea spp.).","authors":"Álvaro Camisón, Pedro Monteiro, F Javier Dorado, Paloma Sánchez-Bel, Frederico Leitão, Mónica Meijón, Gloria Pinto","doi":"10.1093/treephys/tpaf016","DOIUrl":"10.1093/treephys/tpaf016","url":null,"abstract":"<p><p>Ink disease caused by the hemibiotrophic root pathogen Phytophthora cinnamomi (Pc) is devastating for the European chestnut (Castanea sativa), unlike Asian chestnuts and interspecific hybrids, which are resistant to Pc. The role that hormone responses play for Pc resistance remains little understood, especially regarding the temporal regulation of hormone responses. We explored the relationship between changes in tree health and physiology and alterations in leaf and root phytohormones and primary and secondary metabolites during compatible and incompatible Castanea spp.-Pc interactions. Susceptible (S) C. sativa and resistant (R) C. sativa × C. crenata ramets were inoculated with Pc in roots and assessed for disease progression, leaf physiology and biochemistry at 1, 3, 5 and 8 days after inoculation (d.a.i.). In S chestnuts, Pc increasingly deteriorated the leaf physiological functioning by decreasing leaf CO2 assimilation, stomatal conductance, transpiration rate, chlorophylls content and the maximum quantum yield of the photosystem II over time, triggering aerial symptoms (leaf wilting and chlorosis) 8 d.a.i. Pc had little impact on the leaf physiological functioning of R chestnuts, which remained asymptomatic. In roots of S chestnuts, Pc transiently induced jasmonates signaling (5 d.a.i.) while impairing root carbohydrates metabolism over time. In leaves, a transient antioxidant burst (5 d.a.i.) followed by abscisic acid (ABA) accumulation (8 d.a.i.) was observed. R chestnuts responded to Pc by up-regulating root salicylic acid (SA) at early (1 d.a.i.) and late (8 d.a.i.) infection stages, in an antagonistic crosstalk with root ABA. Overall, the results pinpoint an important role of SA in mediating the resistant response of chestnuts to Pc, but also show that the specific hormone pathways induced by Pc are genotype dependent. The study also highlights that the dynamic nature of hormone responses over time must be considered when elucidating hormone-regulated responses to Pc.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":"45 3","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143664646","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":"Prospects for high-throughput estimates of photosynthetic parameters in tropical trees using the Dynamic Assimilation™ Technique.","authors":"Emmelia J Braun, Charles D Southwick, Maquelle N Garcia, Tyeen C Taylor, Kelvin Acebron, João Victor F C Rodrigues, Marciel J Ferreira, Raimundo C de Oliveira, Loren P Albert","doi":"10.1093/treephys/tpae153","DOIUrl":"10.1093/treephys/tpae153","url":null,"abstract":"<p><p>Amazônia is a species-rich region of immense importance to Earth's water and carbon cycling. Photosynthesis drives the global carbon cycle, so understanding photosynthetic differences across diverse landscapes is a key task of ecophysiology and ecosystem science. Unfortunately, due to physiological and logistical constraints, ground-based photosynthesis data in Amazônia remain scarce and the 'traditional' steady-state (SS) method of gas exchange is slow and inefficient. The Dynamic Assimilation™ Technique (DAT) promises a new way to perform A/Ci curves rapidly without requiring SS conditions. Thus far, this technique has only been validated in greenhouse or agricultural-field-grown species and has yet to be tested in forest trees of diverse physiology morphology and environmental adaptation. To test the utility of the DAT in a complex tropical forest ecosystem, we compared the DAT with the SS method in 13 Amazonian trees in situ. We found strong agreement between Vcmax from DAT curves and SS curves, while Jmax was underestimated in DAT curves. We conclude that the DAT provides a robust and rapid estimation of Vcmax. We also identified diverse and unexpected DAT curve shapes among some trees, including the presence of an 'overshoot' in assimilation beyond model-derived ribulose-1,5-bisphosphate (RuBP) regeneration limitations. The presence of overshoot may elucidate microclimate and species differences in RuBP regeneration rates and emphasizes the considerable importance of DAT curve protocol specifications, such as the effect of ramp rate and direction on Jmax and TPU. Overall, the DAT saved time relative to the SS method and proved to be an effective and rapid method for quantifying Vcmax in tropical trees.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142839584","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":"Enhancing Cd and Pb tolerance of Robinia pseudoacacia (black locust) by regulating antioxidant defense system, macroelement uptake and microstructure.","authors":"Xu-Feng Luo, Xuan-Tao Yi, De-Zheng Wang, Jiang-Yao Wang, Peng Zeng, Hang Zhou, Jiao-Feng Gu, Bo-Han Liao, Hao Li","doi":"10.1093/treephys/tpaf015","DOIUrl":"10.1093/treephys/tpaf015","url":null,"abstract":"<p><p>Woody plants have received considerable attention for the phytoremediation of heavy metal-contaminated soil. This study aimed to investigate the changes in antioxidant enzyme activity, macroelement uptake and microstructure of the woody plant Robinia pseudoacacia (black locust) for the phytoremediation of cadmium (Cd) and lead (Pb) co-contaminated soil based on dynamic sampling. The results show that black locust demonstrates strong tolerance in Cd and Pb co-contaminated soil. After 30-120 days of cultivation, the activities of superoxide dismutase, peroxidase and the macroelement (potassium [K] and calcium [Ca]) content in plant leaves significantly declined in response to Cd and Pb. However, after 160 d of cultivation, the antioxidant enzyme activities, chlorophyll, sulfhydryl and soluble protein contents, as well as Ca and magnesium content in plant leaves were returned to normal levels under the 40 mg kg-1 Cd and 1000 mg kg-1 Pb contaminated soil (CdPb3). Meanwhile, K content in plant leaves under the CdPb3 treatment was significantly (P < 0.05) increased by 68.9% compared with the control. Cadmium and Pb were primarily accumulated in black locust roots. Scanning electron microscope analysis indicated that the sieve tubes in the roots and stems of plant might block the transport of Cd and Pb. Transmission electron microscope analysis indicated that the number and volume of osmiophilic particles in plant leaves were increased and the cell walls were thickened in response to Cd and Pb stress. Path analysis further indicated that the growth of plant was related to macroelements uptake and physiological change (photosynthesis, antioxidant enzyme activity and chelation). Thus, black locust could effectively regulate the antioxidant defense system, macroelement absorption and microstructure to enhance plant tolerance to Cd and Pb stress. Moreover, black locust could maintain the normal urease, acid phosphatase and sucrase activities in the Cd and Pb co-contaminated soil. These findings suggest that black locust could be considered as a useful woody plant for the phytostabilization in Cd- and Pb-contaminated soil.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143075568","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":"Enhancing Cd and Pb tolerance of Robinia pseudoacacia (black locust) by regulating antioxidant defense system, macroelement uptake and microstructure.","authors":"Xu-Feng Luo, Xuan-Tao Yi, De-Zheng Wang, Jiang-Yao Wang, Peng Zeng, Hang Zhou, Jiao-Feng Gu, Bo-Han Liao, Hao Li","doi":"10.1093/treephys/tpaf015","DOIUrl":"10.1093/treephys/tpaf015","url":null,"abstract":"<p><p>Woody plants have received considerable attention for the phytoremediation of heavy metal-contaminated soil. This study aimed to investigate the changes in antioxidant enzyme activity, macroelement uptake and microstructure of the woody plant Robinia pseudoacacia (black locust) for the phytoremediation of cadmium (Cd) and lead (Pb) co-contaminated soil based on dynamic sampling. The results show that black locust demonstrates strong tolerance in Cd and Pb co-contaminated soil. After 30-120 days of cultivation, the activities of superoxide dismutase, peroxidase and the macroelement (potassium [K] and calcium [Ca]) content in plant leaves significantly declined in response to Cd and Pb. However, after 160 d of cultivation, the antioxidant enzyme activities, chlorophyll, sulfhydryl and soluble protein contents, as well as Ca and magnesium content in plant leaves were returned to normal levels under the 40 mg kg-1 Cd and 1000 mg kg-1 Pb contaminated soil (CdPb3). Meanwhile, K content in plant leaves under the CdPb3 treatment was significantly (P < 0.05) increased by 68.9% compared with the control. Cadmium and Pb were primarily accumulated in black locust roots. Scanning electron microscope analysis indicated that the sieve tubes in the roots and stems of plant might block the transport of Cd and Pb. Transmission electron microscope analysis indicated that the number and volume of osmiophilic particles in plant leaves were increased and the cell walls were thickened in response to Cd and Pb stress. Path analysis further indicated that the growth of plant was related to macroelements uptake and physiological change (photosynthesis, antioxidant enzyme activity and chelation). Thus, black locust could effectively regulate the antioxidant defense system, macroelement absorption and microstructure to enhance plant tolerance to Cd and Pb stress. Moreover, black locust could maintain the normal urease, acid phosphatase and sucrase activities in the Cd and Pb co-contaminated soil. These findings suggest that black locust could be considered as a useful woody plant for the phytostabilization in Cd- and Pb-contaminated soil.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":"45 3","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143664565","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":"Choosing the right signaling pathway: hormone responses to Phytophthora cinnamomi during compatible and incompatible interactions with chestnut (Castanea spp.).","authors":"Álvaro Camisón, Pedro Monteiro, F Javier Dorado, Paloma Sánchez-Bel, Frederico Leitão, Mónica Meijón, Gloria Pinto","doi":"10.1093/treephys/tpaf016","DOIUrl":"10.1093/treephys/tpaf016","url":null,"abstract":"<p><p>Ink disease caused by the hemibiotrophic root pathogen Phytophthora cinnamomi (Pc) is devastating for the European chestnut (Castanea sativa), unlike Asian chestnuts and interspecific hybrids, which are resistant to Pc. The role that hormone responses play for Pc resistance remains little understood, especially regarding the temporal regulation of hormone responses. We explored the relationship between changes in tree health and physiology and alterations in leaf and root phytohormones and primary and secondary metabolites during compatible and incompatible Castanea spp.-Pc interactions. Susceptible (S) C. sativa and resistant (R) C. sativa × C. crenata ramets were inoculated with Pc in roots and assessed for disease progression, leaf physiology and biochemistry at 1, 3, 5 and 8 days after inoculation (d.a.i.). In S chestnuts, Pc increasingly deteriorated the leaf physiological functioning by decreasing leaf CO2 assimilation, stomatal conductance, transpiration rate, chlorophylls content and the maximum quantum yield of the photosystem II over time, triggering aerial symptoms (leaf wilting and chlorosis) 8 d.a.i. Pc had little impact on the leaf physiological functioning of R chestnuts, which remained asymptomatic. In roots of S chestnuts, Pc transiently induced jasmonates signaling (5 d.a.i.) while impairing root carbohydrates metabolism over time. In leaves, a transient antioxidant burst (5 d.a.i.) followed by abscisic acid (ABA) accumulation (8 d.a.i.) was observed. R chestnuts responded to Pc by up-regulating root salicylic acid (SA) at early (1 d.a.i.) and late (8 d.a.i.) infection stages, in an antagonistic crosstalk with root ABA. Overall, the results pinpoint an important role of SA in mediating the resistant response of chestnuts to Pc, but also show that the specific hormone pathways induced by Pc are genotype dependent. The study also highlights that the dynamic nature of hormone responses over time must be considered when elucidating hormone-regulated responses to Pc.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143068214","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":"Variation of root resource acquisition and conservation strategies in a temperate forest is linked with plant growth forms.","authors":"Siyuan Wang, Louise H Comas, Peter B Reich, M Luke McCormack, Richard P Phillips, Jiacun Gu, Tao Sun","doi":"10.1093/treephys/tpaf027","DOIUrl":"https://doi.org/10.1093/treephys/tpaf027","url":null,"abstract":"<p><p>Exploring why species of different plant growth forms can coexist in the same forest is critical for understanding the long-term community stability, but poorly studied on this from root ecological strategies. The aim of this study was to explore the variation of root functional traits among different growth forms and their distribution patterns in root economics space to clarify how plant growth forms affect the root resource acquisition strategies of co-occurring species in a forest community. We sampled 115 co-occurring species with five growth forms (i.e., trees, shrubs, lianas, herbs, and ferns) from a mega-plot (>50 ha) in temperate forest and measured seven root functional traits, including root morphological, anatomical, and chemical traits, that are closely associated with root resource foraging and conservation strategies. We found that root specific length (SRL) and tissue density (RTD) showed wider variations than other traits among the five growth forms. Moreover, compared with clade and mycorrhizal type, variations of SRL and RTD were largely attributed to growth forms. Importantly, 115 co-occurring species were separately aggregated by growth forms along the trade-off dimension of SRL and RTD in root economics space, suggesting the diversity in root resource acquisition strategies at a local forest community is linked to plant growth forms. In particular, herbs were concentrated towards the side of high SRL and RN, by contrast, trees, shrubs, and ferns were positioned at the side of high RTD and C/N, and lianas were located towards the middle. Diverse root resource acquisition strategies in plant growth forms allow them to occupy specific belowground ecological niches, thereby relieving the competition for the common resource. These findings advance our understanding of the mechanism for maintaining community species coexistence from a below-ground perspective.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143558165","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":"Tree carbon allocation to root exudates: Implications for carbon budgets, soil sequestration, and drought response.","authors":"Melanie Brunn, Carsten W Mueller, Nikhil R Chari, Ina C Meier, Sophie Obersteiner, Richard P Phillips, Benton Taylor, Shersingh Joseph Tumber-Dávila, Sami Ullah, Tamir Klein","doi":"10.1093/treephys/tpaf026","DOIUrl":"https://doi.org/10.1093/treephys/tpaf026","url":null,"abstract":"<p><p>Root carbon (C) exudation plays a central role in nutrient acquisition, microbially-mediated organic matter decomposition, and many other critical ecosystem processes. While it is well-known that roots respond strongly to belowground resources, we have a limited quantitative understanding about C allocation to exudates and its fate in soil under changing water availability. This review synthesizes the importance of exudate C fluxes, summarizes studies quantifying mass-specific exudation rate (SER), total exudation rate (TER), and root exudate fraction (REF; the proportion of TER in a plant's C allocation), examines drought effects, and highlights key research priorities to advance the understanding of C allocation to exudates in forest ecosystems. On average, SER is often less than 1 mg C g dry root-1 day-1, TER is 3.8 Pg C year-1 and REF varies between 1-17% of net primary production. Spatiotemporal variations in exudation, including seasonal and daily patterns, and subsoil exudation remain critical knowledge gaps. We show that many studies report a 1.2- to 11-fold increase in SER and REF in response to drought. However, TER often remains unchanged, suggesting that absolute exudate C inputs to the soil may stay constant under drought conditions. Disentangling the individual impacts of soil and air drought as well as drought legacy impacts on ecosystem C dynamics are overlooked aspects. By estimating the differences in rhizosphere formation and exudation across various forest biomes, we find that exudate-affected soil volumes are highest in tropical forests and lowest in boreal forests. While current research emphasizes significant C allocation from the canopy to soil via exudates, understanding exudation dynamics and biome-specific responses to drought by using standardized protocols is essential. Expanding these insights is critical for comprehending the role of root exudates in soil organic matter formation, ecosystem resilience, and adaptation to climate change.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143558164","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}