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Burkhardt J, Zinsmeister D, Roth-Nebelsick A, Hüging H, Pariyar S. Ambient aerosols increase stomatal transpiration and conductance of hydroponic sunflowers by extending the hydraulic system to the leaf surface. Front Plant Sci 2023; 14:1275358. [PMID: 38098798 PMCID: PMC10720890 DOI: 10.3389/fpls.2023.1275358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Accepted: 11/06/2023] [Indexed: 12/17/2023]
Abstract
Introduction Many atmospheric aerosols are hygroscopic and play an important role in cloud formation. Similarly, aerosols become sites of micro-condensation when they deposit to the upper and lower surfaces of leaves. Deposited salts, in particular can trigger condensation at humidities considerably below atmospheric saturation, according to their hygroscopicity and the relative humidity within the leaf boundary layer. Salt induced water potential gradients and the resulting dynamics of concentrated salt solutions can be expected to affect plant water relations. Methods Hydroponic sunflowers were grown in filtered (FA) and unfiltered, ambient air (AA). Sap flow was measured for 18 days and several indicators of incipient drought stress were studied. Results At 2% difference in mean vapor pressure deficit (D), AA sunflowers had 49% higher mean transpiration rates, lower osmotic potential, higher proline concentrations, and different tracer transport patterns in the leaf compared to FA sunflowers. Aerosols increased plant conductance particularly at low D. Discussion The proposed mechanism is that thin aqueous films of salt solutions from deliquescent deposited aerosols enter into stomata and cause an extension of the hydraulic system. This hydraulic connection leads - parallel to stomatal water vapor transpiration - to wick-like stomatal loss of liquid water and to a higher impact of D on plant water loss. Due to ample water supply by hydroponic cultivation, AA plants thrived as well as FA plants, but under more challenging conditions, aerosol deposits may make plants more susceptible to drought stress.
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Affiliation(s)
- Juergen Burkhardt
- Institute of Crop Science and Resource Conservation, Plant Nutrition Group, University of Bonn, Bonn, Germany
| | - Daniel Zinsmeister
- Institute of Crop Science and Resource Conservation, Plant Nutrition Group, University of Bonn, Bonn, Germany
| | - Anita Roth-Nebelsick
- Department Palaeontology, State Museum of Natural History Stuttgart, Stuttgart, Germany
| | - Hubert Hüging
- Institute of Crop Science and Resource Conservation, Crop Science Group, University of Bonn, Bonn, Germany
| | - Shyam Pariyar
- Institute of Crop Science and Resource Conservation, Plant Nutrition Group, University of Bonn, Bonn, Germany
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Herrera JC, Calderan A, Gambetta GA, Peterlunger E, Forneck A, Sivilotti P, Cochard H, Hochberg U. Stomatal responses in grapevine become increasingly more tolerant to low water potentials throughout the growing season. Plant J 2022; 109:804-815. [PMID: 34797611 DOI: 10.1111/tpj.15591] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Revised: 11/08/2021] [Accepted: 11/15/2021] [Indexed: 05/27/2023]
Abstract
The leaf of a deciduous species completes its life cycle in a few months. During leaf maturation, osmolyte accumulation leads to a significant reduction of the turgor loss point (ΨTLP ), a known marker for stomatal closure. Here we exposed two grapevine cultivars to drought at three different times during the growing season to explore if the seasonal decrease in leaf ΨTLP influences the stomatal response to drought. The results showed a significant seasonal shift in the response of stomatal conductance to stem water potential (gs ~Ψstem ), demonstrating that grapevines become increasingly tolerant to low Ψstem as the season progresses in coordination with the decrease in ΨTLP . We also used the SurEau hydraulic model to demonstrate a direct link between osmotic adjustment and the plasticity of gs ~Ψstem . To understand the possible advantages of gs ~Ψstem plasticity, we incorporated a seasonally dynamic leaf osmotic potential into the model that simulated stomatal conductance under several water availabilities and climatic scenarios. The model demonstrated that a seasonally dynamic stomatal closure threshold results in trade-offs: it reduces the time to turgor loss under sustained long-term drought, but increases overall gas exchange particularly under seasonal shifts in temperature and stochastic water availability. A projected hotter future is expected to lower the increase in gas exchange that plants gain from the seasonal shift in gs ~Ψstem . These findings show that accounting for dynamic stomatal regulation is critical for understanding drought tolerance.
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Affiliation(s)
- Jose Carlos Herrera
- Institute of Viticulture and Pomology, Department of Crop Sciences, University of Natural Resources and Life Sciences, Vienna (BOKU), Tulln, Austria
| | - Alberto Calderan
- Department of Agricultural, Food, Environmental and Animal Sciences, University of Udine, Udine, Italy
- Department of Life Sciences, University of Trieste, Trieste, Italy
| | - Gregory A Gambetta
- EGFV, Bordeaux-Sciences Agro, INRAE, Université de Bordeaux, ISVV, Villenave d'Ornon, France
| | - Enrico Peterlunger
- Department of Agricultural, Food, Environmental and Animal Sciences, University of Udine, Udine, Italy
| | - Astrid Forneck
- Institute of Viticulture and Pomology, Department of Crop Sciences, University of Natural Resources and Life Sciences, Vienna (BOKU), Tulln, Austria
| | - Paolo Sivilotti
- Department of Agricultural, Food, Environmental and Animal Sciences, University of Udine, Udine, Italy
| | - Herve Cochard
- INRAE, PIAF, Université Clermont-Auvergne, Clermont-Ferrand, 63000, France
| | - Uri Hochberg
- Institute of Soil, Water and Environmental Sciences, Volcani Center, Agricultural Research Organization, Bet-Dagan, Israel
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Onyemaobi O, Sangma H, Garg G, Wallace X, Kleven S, Suwanchaikasem P, Roessner U, Dolferus R. Reproductive Stage Drought Tolerance in Wheat: Importance of Stomatal Conductance and Plant Growth Regulators. Genes (Basel) 2021; 12:1742. [PMID: 34828346 DOI: 10.3390/genes12111742] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 10/28/2021] [Accepted: 10/28/2021] [Indexed: 12/13/2022] Open
Abstract
Drought stress requires plants to adjust their water balance to maintain tissue water levels. Isohydric plants (‘water-savers’) typically achieve this through stomatal closure, while anisohydric plants (‘water-wasters’) use osmotic adjustment and maintain stomatal conductance. Isohydry or anisohydry allows plant species to adapt to different environments. In this paper we show that both mechanisms occur in bread wheat (Triticum aestivum L.). Wheat lines with reproductive drought-tolerance delay stomatal closure and are temporarily anisohydric, before closing stomata and become isohydric at higher threshold levels of drought stress. Drought-sensitive wheat is isohydric from the start of the drought treatment. The capacity of the drought-tolerant line to maintain stomatal conductance correlates with repression of ABA synthesis in spikes and flag leaves. Gene expression profiling revealed major differences in the drought response in spikes and flag leaves of both wheat lines. While the isohydric drought-sensitive line enters a passive growth mode (arrest of photosynthesis, protein translation), the tolerant line mounts a stronger stress defence response (ROS protection, LEA proteins, cuticle synthesis). The drought response of the tolerant line is characterised by a strong response in the spike, displaying enrichment of genes involved in auxin, cytokinin and ethylene metabolism/signalling. While isohydry may offer advantages for longer term drought stress, anisohydry may be more beneficial when drought stress occurs during the critical stages of wheat spike development, ultimately improving grain yield.
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Chen Z, Zhang Y, Yuan W, Zhu S, Pan R, Wan X, Liu S. Coordinated variation in stem and leaf functional traits of temperate broadleaf tree species in the isohydric- anisohydric spectrum. Tree Physiol 2021; 41:1601-1610. [PMID: 33693879 DOI: 10.1093/treephys/tpab028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 02/08/2021] [Indexed: 06/12/2023]
Abstract
Stomatal regulation serves as an important strategy for plants to adapt to drought. However, the understanding of how complexes of plant-functional traits vary along the continuum from isohydry to anisohydry remains insufficient. In this study, we investigated a proxy of the degree of iso/anisohydry-the water potential at stomatal closure-and a series of functional traits of leaves and branches in 20 temperate broadleaf species planted in an arid limestone habitat in northern China. The results showed that the water potential at stomatal closure was significantly correlated with many functional traits. At the anisohydric end of the spectrum, species had a higher leaf carbon content and vein density, a greater stomatal length, a thicker lower leaf epidermis, higher embolism resistance, higher wood density, a greater Huber value, a greater ratio of fiber wall thickness to xylem lumen diameter, a larger proportion of total fiber wall area to xylem cross-sectional area, a lower water potential at the turgor loss point (TLP), a smaller relative water content at the TLP, a lower osmotic potential at full turgor and a smaller specific leaf area. It is concluded that a continuum of coordination and trade-offs among co-evolved anatomical and physiological traits gives rise to the spectrum from isohydry to anisohydry spanned by the 20 tree species, and the anisohydric species showed stronger stress resistance, with greater investment in stems and leaves than the isohydric species to maintain stomatal opening under drought conditions.
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Affiliation(s)
- Zhicheng Chen
- Research Institute of Forestry New Technology, Chinese Academy of Forestry, Beijing 100091, China
| | - Yongtao Zhang
- Mountain Tai Forest Ecosystem Research Station of National Forestry and Grassland Administration, Forestry College of Shandong Agricultural University, Taian 271018, China
| | - Weijie Yuan
- Experimental Center of Forestry in North China, Chinese Academy of Forestry, Beijing 102300, China
| | - Shidan Zhu
- Guangxi Key Laboratory of Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning 530004, China
| | - Ruihua Pan
- School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, China
| | - Xianchong Wan
- Research Institute of Forestry New Technology, Chinese Academy of Forestry, Beijing 100091, China
| | - Shirong Liu
- Key laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration, Research Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry, Beijing 100091, China
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Sánchez‐Ortiz A, Mateo‐Sanz JM, Nadal M, Lampreave M. Water stress assessment on grapevines by using classification and regression trees. Plant Direct 2021; 5:e00319. [PMID: 33851071 PMCID: PMC8022199 DOI: 10.1002/pld3.319] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Revised: 03/07/2021] [Accepted: 03/10/2021] [Indexed: 06/12/2023]
Abstract
Multiple factors, such as the vineyard environment and winemaking practices, are known to affect the development of vines as well as the final composition of grapes. Water stress promotes the synthesis of phenols and is associated with grape quality as long as it does not inhibit production. To identify the key parameters for managing water stress and grape quality, multivariate statistical analysis is essential. Classification and regression trees are methods for constructing prediction models from data, especially when data are complex and when constructing a single global model is difficult and models are challenging to interpret. The models were obtained by recursively partitioning the data space and fitting a simple prediction model within each partition. The partitioning can be represented graphically as a decision tree. This approach permitted the most decisive variables for predicting the most vulnerable vineyards and wine quality parameters associated with water stress. In Priorat AOC, Carignan grapevines had the highest water potential and abscisic acid concentration in the early growth plant stages and permitted vineyards to be classified by mesoclimate. This information is useful for identifying which measurements could most easily differentiate between early and late-ripening vineyards. LWP and Ts during an early physiological stage (pea size) permitted warm and cold areas to be differentiated.
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Affiliation(s)
- Antoni Sánchez‐Ortiz
- Departament de Bioquímica i BiotecnologiaFacultat d'Enologia de TarragonaUniversitat Rovira i VirgiliTarragonaSpain
| | - Josep M. Mateo‐Sanz
- Departament d'Enginyeria QuimicaETSEQUniversitat Rovira i VirgiliTarragonaSpain
| | - Montserrat Nadal
- Departament de Bioquímica i BiotecnologiaFacultat d'Enologia de TarragonaUniversitat Rovira i VirgiliTarragonaSpain
| | - Míriam Lampreave
- Departament de Bioquímica i BiotecnologiaFacultat d'Enologia de TarragonaUniversitat Rovira i VirgiliTarragonaSpain
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Pratt RB, Tobin MF, Jacobsen AL, Traugh CA, De Guzman ME, Hayes CC, Toschi HS, MacKinnon ED, Percolla MI, Clem ME, Smith PT. Starch storage capacity of sapwood is related to dehydration avoidance during drought. Am J Bot 2021; 108:91-101. [PMID: 33349932 DOI: 10.1002/ajb2.1586] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 09/22/2020] [Indexed: 05/26/2023]
Abstract
PREMISE The xylem tissue of plants performs three principal functions: transport of water, support of the plant body, and nutrient storage. Tradeoffs may arise because different structural requirements are associated with different functions or because suites of traits are under selection that relate to resource acquisition, use, and turnover. The structural and functional basis of xylem storage is not well established. We hypothesized that greater starch storage would be associated with greater sapwood parenchyma and reduced fibers, which would compromise resistance to xylem tensions during dehydration. METHODS We measured cavitation resistance, minimum water potential, starch content, and sapwood parenchyma and fiber area in 30 species of southern California chaparral shrubs (evergreen and deciduous). RESULTS We found that species storing greater starch within their xylem tended to avoid dehydration and were less cavitation resistant, and this was supported by phylogenetic independent contrasts. Greater sapwood starch was associated with greater parenchyma area and reduced fiber area. For species without living fibers, the associations with parenchyma were stronger, suggesting that living fibers may expand starch storage capacity while also contributing to the support function of the vascular tissue. Drought-deciduous species were associated with greater dehydration avoidance than evergreens. CONCLUSIONS Evolutionary forces have led to an association between starch storage and dehydration resistance as part of an adaptive suite of traits. We found evidence for a tradeoff between tissue mechanical traits and starch storage; moreover, the evolution of novel strategies, such as starch-storing living fibers, may mitigate the strength of this tradeoff.
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Affiliation(s)
- R Brandon Pratt
- California State University, Bakersfield, Department of Biology, Bakersfield, California, 93311, USA
| | - Michael F Tobin
- University of Houston-Downtown, Department of Natural Sciences, One Main Street, Houston, Texas, 77002, USA
| | - Anna L Jacobsen
- California State University, Bakersfield, Department of Biology, Bakersfield, California, 93311, USA
| | - Courtney A Traugh
- California State University, Bakersfield, Department of Biology, Bakersfield, California, 93311, USA
| | - Mark E De Guzman
- California State University, Bakersfield, Department of Biology, Bakersfield, California, 93311, USA
| | - Christine C Hayes
- California State University, Bakersfield, Department of Biology, Bakersfield, California, 93311, USA
| | - Hayden S Toschi
- California State University, Bakersfield, Department of Biology, Bakersfield, California, 93311, USA
| | - Evan D MacKinnon
- California State University, Bakersfield, Department of Biology, Bakersfield, California, 93311, USA
| | - Marta I Percolla
- California State University, Bakersfield, Department of Biology, Bakersfield, California, 93311, USA
| | - Michael E Clem
- California State University, Bakersfield, Department of Biology, Bakersfield, California, 93311, USA
| | - Paul T Smith
- California State University, Bakersfield, Department of Biology, Bakersfield, California, 93311, USA
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7
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Hoshika Y, Fares S, Pellegrini E, Conte A, Paoletti E. Water use strategy affects avoidance of ozone stress by stomatal closure in Mediterranean trees-A modelling analysis. Plant Cell Environ 2020; 43:611-623. [PMID: 31834637 DOI: 10.1111/pce.13700] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 10/28/2019] [Accepted: 12/08/2019] [Indexed: 06/10/2023]
Abstract
Both ozone (O3 ) and drought can limit carbon fixation by forest trees. To cope with drought stress, plants have isohydric or anisohydric water use strategies. Ozone enters plant tissues through stomata. Therefore, stomatal closure can be interpreted as avoidance to O3 stress. Here, we applied an optimization model of stomata involving water, CO2 , and O3 flux to test whether isohydric and anisohydric strategies may affect avoidance of O3 stress by stomatal closure in four Mediterranean tree species during drought. The data suggest that stomatal closure represents a response to avoid damage to the photosynthetic mechanisms under elevated O3 depending on plant water use strategy. Under high-O3 and well-watered conditions, isohydric species limited O3 fluxes by stomatal closure, whereas anisohydric species activated a tolerance response and did not actively close stomata. Under both O3 and drought stress, however, anisohydric species enhanced the capacity of avoidance by closing stomata to cope with the severe oxidative stress. In the late growing season, regardless of the water use strategy, the efficiency of O3 stress avoidance decreased with leaf ageing. As a result, carbon assimilation rate was decreased by O3 while stomata did not close enough to limit transpirational water losses.
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Affiliation(s)
- Yasutomo Hoshika
- Institute of Research on Terrestrial Ecosystems (IRET), National Research Council of Italy (CNR), Sesto Fiorentino, Italy
| | - Silvano Fares
- Council for Agricultural Research and Economics (CREA), Research Centre for Forestry and Wood, Rome, Italy
| | - Elisa Pellegrini
- Department of Agriculture, Food and Environment, University of Pisa, Pisa, Italy
- CIRSEC, Centre for Climatic Change Impact, University of Pisa, Pisa, Italy
| | - Adriano Conte
- Council for Agricultural Research and Economics (CREA), Research Centre for Forestry and Wood, Rome, Italy
| | - Elena Paoletti
- Institute of Research on Terrestrial Ecosystems (IRET), National Research Council of Italy (CNR), Sesto Fiorentino, Italy
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8
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Kannenberg SA, Phillips RP. Non-structural carbohydrate pools not linked to hydraulic strategies or carbon supply in tree saplings during severe drought and subsequent recovery. Tree Physiol 2020; 40:259-271. [PMID: 31860721 DOI: 10.1093/treephys/tpz132] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 10/30/2019] [Accepted: 11/16/2019] [Indexed: 06/10/2023]
Abstract
Non-structural carbohydrate (NSC) pools fluctuate based on the interplay between photosynthesis, demand from various carbon (C) sinks and tree hydraulic status. Thus, it has been hypothesized that tree species with isohydric stomatal control (i.e., trees that close stomata rapidly in response to drought) rely heavily on NSC pools to sustain metabolism, which can lead to negative physiological consequences such as C depletion. Here, we seek to use a species' degree of isohydry or anisohydry as a conceptual framework for understanding the interrelations between photosynthetic C supply, hydraulic damage and fluctuations in NSC pools. We conducted a 6-week experimental drought, followed by a 6-week recovery period, in a greenhouse on seven tree species that span the spectrum from isohydric to anisohydric. Throughout the experiment, we measured photosynthesis, hydraulic damage and NSC pools. Non-structural carbohydrate pools were remarkably stable across species and tissues-even highly isohydric species that drastically reduced C assimilation were able to maintain stored C. Despite these static NSC pools, we still inferred an important role for stored C during drought, as most species converted starches into sugars during water stress (and back again post-drought). Finally, we did not observe any linkages between C supply, hydraulic damage and NSC pools, indicating that NSC was maintained independent of variation in photosynthesis and hydraulic function. Our results advance the idea that C depletion is a rare phenomenon due to either active maintenance of NSC pools or sink limitation, and thus question the hypothesis that reductions in C assimilation necessarily lead to C depletion.
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Affiliation(s)
- Steven A Kannenberg
- School of Biological Sciences, University of Utah, 257 1400 East, Salt Lake City, UT 84112, USA
- Department of Biology, Indiana University, 1001 East 3rd Street, Bloomington, IN 47405, USA
| | - Richard P Phillips
- Department of Biology, Indiana University, 1001 East 3rd Street, Bloomington, IN 47405, USA
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Berry ZC, Espejel X, Williams-Linera G, Asbjornsen H. Linking coordinated hydraulic traits to drought and recovery responses in a tropical montane cloud forest. Am J Bot 2019; 106:1316-1326. [PMID: 31518000 DOI: 10.1002/ajb2.1356] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 07/25/2019] [Indexed: 06/10/2023]
Abstract
PREMISE Understanding plant hydraulic functioning and water balance during drought has become key in predicting species survival and recovery. However, there are few insightful studies that couple physiological and morphological attributes for many ecosystems, such as the vulnerable Tropical Montane Cloud Forests (TMCF). In this study, we evaluated drought resistance and recovery for saplings for five tree species spanning deciduous to evergreen habits from a Mexican TMCF. METHODS In drought simulations, water was withheld until plants reached species-specific P50 or P88 values (pressures required to induce a 50 or 88% loss in hydraulic conductivity), then they were rewatered. Drought resistance was considered within the isohydric-anisohydric framework and compared to leaf gas exchange, water status, pressure-volume curves, specific leaf area, and stomatal density. RESULTS The TMCF species closed stomata well before significant losses in hydraulic conductivity (isohydric). Yet, despite the coordination of these traits, the traits were not useful for predicting the time needed for the species to reach critical hydraulic thresholds. Instead, maximum photosynthetic rates explained these times, reinforcing the linkage between hydraulic and carbon dynamics. Despite their varying hydraulic conductivities, stomatal responses, and times to hydraulic thresholds, 58 of the 60 study plants recovered after the rewatering. The recovery of photosynthesis and stomatal conductance can be explained by the P50 values and isohydry. CONCLUSIONS This study raises new questions surrounding drought management strategies, recovery processes, and how lethal thresholds are defined. Further studies need to consider the role of water and carbon balance in allowing for both survival and recovery from drought.
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Affiliation(s)
- Z Carter Berry
- Schmid College of Science and Technology, Chapman University, Orange, CA, 92866, USA
| | - Ximena Espejel
- Instituto de Ecología, A.C., Carretera Antigua a Coatepec 351, Xalapa, Veracruz, 91070, México
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Novick KA, Konings AG, Gentine P. Beyond soil water potential: An expanded view on isohydricity including land-atmosphere interactions and phenology. Plant Cell Environ 2019; 42:1802-1815. [PMID: 30632172 DOI: 10.1111/pce.13517] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 01/02/2019] [Accepted: 01/07/2019] [Indexed: 05/21/2023]
Abstract
Over the past decade, the concept of isohydry or anisohydry, which describes the link between soil water potential (ΨS ), leaf water potential (ΨL ), and stomatal conductance (gs ), has soared in popularity. However, its utility has recently been questioned, and a surprising lack of coordination between the dynamics of ΨL and gs across biomes has been reported. Here, we offer a more expanded view of the isohydricity concept that considers effects of vapour pressure deficit (VPD) and leaf area index (AL ) on the apparent sensitivities of ΨL and gs to drought. After validating the model with tree- and ecosystem-scale data, we find that within a site, isohydricity is a strong predictor of limitations to stomatal function, though variation in VPD and leaf area, among other factors, can challenge its diagnosis. Across sites, the theory predicts that the degree of isohydricity is a good predictor of the sensitivity of gs to declining soil water in the absence of confounding effects from other drivers. However, if VPD effects are significant, they alone are sufficient to decouple the dynamics of ΨL and gs entirely. We conclude with a set of practical recommendations for future applications of the isohydricity framework within and across sites.
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Affiliation(s)
- Kimberly A Novick
- School of Public and Environmental Affairs, Indiana University Bloomington, Bloomington, Indiana
| | - Alexandra G Konings
- Department of Earth System Science, Stanford University, Stanford, California
| | - Pierre Gentine
- Department of Earth and Environmental Engineering, Columbia University, New York, New York
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11
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Polle A, Chen SL, Eckert C, Harfouche A. Engineering Drought Resistance in Forest Trees. Front Plant Sci 2019; 9:1875. [PMID: 30671067 DOI: 10.3389/fpls.2018.0187] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 12/04/2018] [Indexed: 05/27/2023]
Abstract
Climatic stresses limit plant growth and productivity. In the past decade, tree improvement programs were mainly focused on yield but it is obvious that enhanced stress resistance is also required. In this review we highlight important drought avoidance and tolerance mechanisms in forest trees. Genomes of economically important trees species with divergent resistance mechanisms can now be exploited to uncover the mechanistic basis of long-term drought adaptation at the whole plant level. Molecular tree physiology indicates that osmotic adjustment, antioxidative defense and increased water use efficiency are important targets for enhanced drought tolerance at the cellular and tissue level. Recent biotechnological approaches focused on overexpression of genes involved in stress sensing and signaling, such as the abscisic acid core pathway, and down-stream transcription factors. By this strategy, a suite of defense systems was recruited, generally enhancing drought and salt stress tolerance under laboratory conditions. However, field studies are still scarce. Under field conditions trees are exposed to combinations of stresses that vary in duration and magnitude. Variable stresses may overrule the positive effect achieved by engineering an individual defense pathway. To assess the usability of distinct modifications, large-scale experimental field studies in different environments are necessary. To optimize the balance between growth and defense, the use of stress-inducible promoters may be useful. Future improvement programs for drought resistance will benefit from a better understanding of the intricate networks that ameliorate molecular and ecological traits of forest trees.
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Affiliation(s)
- Andrea Polle
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
- Forest Botany and Tree Physiology, University of Goettingen, Göttingen, Germany
- Centre of Biodiversity and Sustainable Land Use, University of Goettingen, Göttingen, Germany
| | - Shao Liang Chen
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
| | - Christian Eckert
- Forest Botany and Tree Physiology, University of Goettingen, Göttingen, Germany
| | - Antoine Harfouche
- Department for Innovation in Biological, Agrofood and Forest systems, University of Tuscia, Viterbo, Italy
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12
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Polle A, Chen SL, Eckert C, Harfouche A. Engineering Drought Resistance in Forest Trees. Front Plant Sci 2019; 9:1875. [PMID: 30671067 PMCID: PMC6331418 DOI: 10.3389/fpls.2018.01875] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 12/04/2018] [Indexed: 05/03/2023]
Abstract
Climatic stresses limit plant growth and productivity. In the past decade, tree improvement programs were mainly focused on yield but it is obvious that enhanced stress resistance is also required. In this review we highlight important drought avoidance and tolerance mechanisms in forest trees. Genomes of economically important trees species with divergent resistance mechanisms can now be exploited to uncover the mechanistic basis of long-term drought adaptation at the whole plant level. Molecular tree physiology indicates that osmotic adjustment, antioxidative defense and increased water use efficiency are important targets for enhanced drought tolerance at the cellular and tissue level. Recent biotechnological approaches focused on overexpression of genes involved in stress sensing and signaling, such as the abscisic acid core pathway, and down-stream transcription factors. By this strategy, a suite of defense systems was recruited, generally enhancing drought and salt stress tolerance under laboratory conditions. However, field studies are still scarce. Under field conditions trees are exposed to combinations of stresses that vary in duration and magnitude. Variable stresses may overrule the positive effect achieved by engineering an individual defense pathway. To assess the usability of distinct modifications, large-scale experimental field studies in different environments are necessary. To optimize the balance between growth and defense, the use of stress-inducible promoters may be useful. Future improvement programs for drought resistance will benefit from a better understanding of the intricate networks that ameliorate molecular and ecological traits of forest trees.
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Affiliation(s)
- Andrea Polle
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
- Forest Botany and Tree Physiology, University of Goettingen, Göttingen, Germany
- Centre of Biodiversity and Sustainable Land Use, University of Goettingen, Göttingen, Germany
| | - Shao Liang Chen
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
| | - Christian Eckert
- Forest Botany and Tree Physiology, University of Goettingen, Göttingen, Germany
| | - Antoine Harfouche
- Department for Innovation in Biological, Agrofood and Forest systems, University of Tuscia, Viterbo, Italy
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Yi K, Maxwell JT, Wenzel MK, Roman DT, Sauer PE, Phillips RP, Novick KA. Linking variation in intrinsic water-use efficiency to isohydricity: a comparison at multiple spatiotemporal scales. New Phytol 2019; 221:195-208. [PMID: 30117538 DOI: 10.1111/nph.15384] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 07/06/2018] [Indexed: 06/08/2023]
Abstract
Species-specific responses of plant intrinsic water-use efficiency (iWUE) to multiple environmental drivers associated with climate change, including soil moisture (θ), vapor pressure deficit (D), and atmospheric CO2 concentration (ca ), are poorly understood. We assessed how the iWUE and growth of several species of deciduous trees that span a gradient of isohydric to anisohydric water-use strategies respond to key environmental drivers (θ, D and ca ). iWUE was calculated for individual tree species using leaf-level gas exchange and tree-ring δ13 C in wood measurements, and for the whole forest using the eddy covariance method. The iWUE of the isohydric species was generally more sensitive to environmental change than the anisohydric species was, and increased significantly with rising D during the periods of water stress. At longer timescales, the influence of ca was pronounced for isohydric tulip poplar but not for others. Trees' physiological responses to changing environmental drivers can be interpreted differently depending on the observational scale. Care should be also taken in interpreting observed or modeled trends in iWUE that do not explicitly account for the influence of D.
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Affiliation(s)
- Koong Yi
- School of Public and Environmental Affairs, Indiana University Bloomington, 1315 East Tenth Street, Bloomington, IN, 47405, USA
| | - Justin T Maxwell
- Department of Geography, Indiana University Bloomington, 701 East Kirkwood Avenue, Bloomington, IN, 47405, USA
| | - Matthew K Wenzel
- School of Public and Environmental Affairs, Indiana University Bloomington, 1315 East Tenth Street, Bloomington, IN, 47405, USA
| | - D Tyler Roman
- US Department of Agriculture Forest Service, Northern Research Station, 1831 Highway 169 East, Grand Rapids, MN, 55744, USA
| | - Peter E Sauer
- Department of Geological Science, Indiana University Bloomington, 1001 East Tenth Street, Bloomington, IN, 47405, USA
| | - Richard P Phillips
- Department of Biology, Indiana University Bloomington, 1001 East Third Street, Bloomington, IN, 47405, USA
| | - Kimberly A Novick
- School of Public and Environmental Affairs, Indiana University Bloomington, 1315 East Tenth Street, Bloomington, IN, 47405, USA
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14
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Hochberg U, Rockwell FE, Holbrook NM, Cochard H. Iso/Anisohydry: A Plant-Environment Interaction Rather Than a Simple Hydraulic Trait. Trends Plant Sci 2018; 23:112-120. [PMID: 29223922 DOI: 10.1016/j.tplants.2017.11.002] [Citation(s) in RCA: 120] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 11/01/2017] [Accepted: 11/06/2017] [Indexed: 05/04/2023]
Abstract
Plants are frequently classified as isohydric or anisohydric in an attempt to portray their water relations strategy or ecological niche. However, despite the popularity of the iso/anisohydric classification, the underlying biology remains unclear. We use here a simple hydraulic model and the extensive literature on grapevine hydraulics to illustrate that the iso/anisohydric classification of a plant depends on the definition used and the environment in which it is grown, rather than describing an intrinsic property of the plant itself. We argue that abandoning the iso/anisohydric terminology and returning to a more fundamental hydraulic framework would provide a stronger foundation for species comparisons and ecological predictions.
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Affiliation(s)
- Uri Hochberg
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA.
| | - Fulton E Rockwell
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - N Michele Holbrook
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
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15
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Wu X, Tang Y, Chen Y, Wen J, Xie Y, Lu S. Sap flow characteristics and responses to summer rainfall for Pinus tabulaeformis and Hippophae rhamnoides in the Loess hilly region of China. Ecol Evol 2018; 8:617-630. [PMID: 29321898 PMCID: PMC5756875 DOI: 10.1002/ece3.3639] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 09/15/2017] [Accepted: 10/08/2017] [Indexed: 11/10/2022] Open
Abstract
As a major driving element of the structure and function of arid and semiarid ecosystems, rainfall is the essential factor limiting plant biological processes. To clarify the characteristics of transpiration and responses to summer rainfall, sap flow density (Fd) of Pinus tabulaeformis and Hippophae rhamnoides was monitored using thermal dissipation probes. In addition, midday leaf water potential (ψm) and leaf stomatal conductance (Gs) were also analyzed to determine water use strategies. The results indicated that the diurnal variation in the normalized Fd values exhibited a single-peak curve for P. tabulaeformis, while H. rhamnoides showed multiple peaks. The normalized Fd for P. tabulaeformis remained relatively stable regardless of rainfall events. However, there was also a significant increase in the normalized Fd for H. rhamnoides in response to rainfall in June and August (p < .05), although no significant differences were observed in July. The normalized Fd values for P. tabulaeformis and H. rhamnoides fitted well with the derived variable of transpiration, an integrated index calculated from the vapor pressure deficit and solar radiation (Rs), using an exponential saturation function. The differences in fitting coefficients suggested that H. rhamnoides showed more sensitivity to summer rainfall (p < .01) than P. tabulaeformis. Furthermore, during the study period, P. tabulaeformis reduced Gs as soil water decreased, maintaining a relatively constant ψm; while H. rhamnoides allowed large fluctuations in ψm to maintain Gs. Therefore, P. tabulaeformis and H. rhamnoides should be considered isohydric and anisohydric species, respectively. And more consideration should be taken for H. rhamnoides in the afforestation activities and the local plantation management under the context of the frequently seasonal drought in the loess hilly region.
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Affiliation(s)
- Xu Wu
- State Key Laboratory of Soil Erosion and Dry‐Land Farming on the Loess PlateauInstitute of Soil and Water ConservationChinese Academy of SciencesMinistry of Water ResourcesYanglingShaanxiChina
- University of Chinese Academy of ScienceBeijingChina
| | - Yakun Tang
- Institute of Soil and Water ConservationNorthwest Agriculture and Forestry UniversityYanglingShaanxiChina
| | - Yunming Chen
- State Key Laboratory of Soil Erosion and Dry‐Land Farming on the Loess PlateauInstitute of Soil and Water ConservationChinese Academy of SciencesMinistry of Water ResourcesYanglingShaanxiChina
- Institute of Soil and Water ConservationNorthwest Agriculture and Forestry UniversityYanglingShaanxiChina
| | - Jie Wen
- College of ForestryNorthwest Agriculture and Forestry UniversityYanglingShaanxiChina
| | - Yuli Xie
- State Key Laboratory of Soil Erosion and Dry‐Land Farming on the Loess PlateauInstitute of Soil and Water ConservationChinese Academy of SciencesMinistry of Water ResourcesYanglingShaanxiChina
- University of Chinese Academy of ScienceBeijingChina
| | - Senbao Lu
- College of ForestryNorthwest Agriculture and Forestry UniversityYanglingShaanxiChina
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16
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Shelden MC, Vandeleur R, Kaiser BN, Tyerman SD. A Comparison of Petiole Hydraulics and Aquaporin Expression in an Anisohydric and Isohydric Cultivar of Grapevine in Response to Water-Stress Induced Cavitation. Front Plant Sci 2017; 8:1893. [PMID: 29163613 PMCID: PMC5681967 DOI: 10.3389/fpls.2017.01893] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Accepted: 10/19/2017] [Indexed: 05/11/2023]
Abstract
We report physiological, anatomical and molecular differences in two economically important grapevine (Vitis vinifera L.) cultivars cv. Grenache (near-isohydric) and Chardonnay (anisohydric) in their response to water-stress induced cavitation. The aim of the study was to compare organ vulnerability (petiole and stem) to cavitation by measuring ultrasonic acoustic emissions (UAE) and percent loss of conductance of potted grapevines subject to the onset of water-stress. Leaf (ψL) and stem water potential (ψS), stomatal conductance (gs), transpiration (E), petiole hydraulics (KPet), and xylem diameter were also measured. Chardonnay displayed hydraulic segmentation based on UAE, with cavitation occurring at a less negative ψL in the petiole than in the stem. Vulnerability segmentation was not observed in Grenache, with both petioles and stems equally vulnerable to cavitation. Leaf water potential that induced 50% of maximum UAE was significantly different between petioles and stems in Chardonnay (ψ50Petiole = -1.14 and ψ50Stem = -2.24 MPa) but not in Grenache (ψ50Petiole = -0.73 and ψ50Stem = -0.78 MPa). Grenache stems appeared more susceptible to water-stress induced cavitation than Chardonnay stems. Grenache displayed (on average) a higher KPet likely due to the presence of larger xylem vessels. A close relationship between petiole hydraulic properties and vine water status was observed in Chardonnay but not in Grenache. Transcriptional analysis of aquaporins in the petioles and leaves (VvPIP1;1, VvPIP2;1, VvPIP2;2 VvPIP2;3, VvTIP1;1, and VvTIP2;1) showed differential regulation diurnally and in response to water-stress. VvPIP2;1 showed strong diurnal regulation in the petioles and leaves of both cultivars with expression highest predawn. Expression of VvPIP2;1 and VvPIP2;2 responded to ψL and ψS in both cultivars indicating the expression of these two genes are closely linked to vine water status. Expression of several aquaporin genes correlated with gas exchange measurements, however, these genes differed between cultivars. In summary, the data shows two contrasting responses in petiole hydraulics and aquaporin expression between the near-isohydric cultivar, Grenache and anisohydric cultivar, Chardonnay.
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Affiliation(s)
- Megan C. Shelden
- ARC Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine, University of Adelaide, Adelaide, SA, Australia
| | - Rebecca Vandeleur
- ARC Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine, University of Adelaide, Adelaide, SA, Australia
| | - Brent N. Kaiser
- Centre for Carbon, Water and Food, School of Life and Environmental Sciences, Faculty of Science, University of Sydney, Sydney, NSW, Australia
| | - Stephen D. Tyerman
- ARC Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine, University of Adelaide, Adelaide, SA, Australia
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17
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Yi K, Dragoni D, Phillips RP, Roman DT, Novick KA. Dynamics of stem water uptake among isohydric and anisohydric species experiencing a severe drought. Tree Physiol 2017; 37:1379-1392. [PMID: 28062727 DOI: 10.1093/treephys/tpw126] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2016] [Accepted: 12/22/2016] [Indexed: 06/06/2023]
Abstract
Predicting the impact of drought on forest ecosystem processes requires an understanding of trees' species-specific responses to drought, especially in the Eastern USA, where species composition is highly dynamic due to historical changes in land use and fire regime. Here, we adapted a framework that classifies trees' water-use strategy along the spectrum of isohydric to anisohydric behavior to determine the responses of three canopy-dominant species to drought. We used a collection of leaf-level gas exchange, tree-level sap flux and stand-level eddy covariance data collected in south-central Indiana from 2011 to 2013, which included an unusually severe drought in the summer of 2012. Our goal was to assess how patterns in the radial profile of sap flux and reliance on hydraulic capacitance differed among species of contrasting water-use strategies. In isohydric species, which included sugar maple (Acer saccharum Marsh.) and tulip poplar (Liriodendron tulipifera L.), we found that the sap flux in the outer xylem experienced dramatic declines during drought, but sap flux at inner xylem was buffered from reductions in water availability. In contrast, for anisohydric oak species (Quercus alba L. and Quercus rubra L.), we observed relatively smaller variations in sap flux during drought in both inner and outer xylem, and higher nighttime refilling when compared with isohydric species. This reliance on nocturnal refilling, which occurred coincident with a decoupling between leaf- and tree-level water-use dynamics, suggests that anisohydric species may benefit from a reliance on hydraulic capacitance to mitigate the risk of hydraulic failure associated with maintaining high transpiration rates during drought. In the case of both isohydric and anisohydric species, our work demonstrates that failure to account for shifts in the radial profile of sap flux during drought could introduce substantial bias in estimates of tree water use during both drought and non-drought periods.
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Affiliation(s)
- Koong Yi
- School of Public and Environmental Affairs, Indiana University Bloomington, 1315 East Tenth Street, Bloomington, IN 47405, USA
| | - Danilo Dragoni
- Department of Geography, Indiana University Bloomington, 701 East Kirkwood Avenue, Bloomington, IN 47405, USA
| | - Richard P Phillips
- Department of Biology, Indiana University Bloomington, 1001 East Third Street, Bloomington, IN 47405, USA
| | - D Tyler Roman
- US Department of Agriculture Forest Service, Northern Research Station, 1831 Highway 169 East , Grand Rapids, MN 55744, USA
| | - Kimberly A Novick
- School of Public and Environmental Affairs, Indiana University Bloomington, 1315 East Tenth Street, Bloomington, IN 47405, USA
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18
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Domec JC, Smith DD, McCulloh KA. A synthesis of the effects of atmospheric carbon dioxide enrichment on plant hydraulics: implications for whole-plant water use efficiency and resistance to drought. Plant Cell Environ 2017; 40:921-937. [PMID: 27739596 DOI: 10.1111/pce.12843] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 09/18/2016] [Accepted: 09/21/2016] [Indexed: 06/06/2023]
Abstract
Here, we summarize studies on the effects of elevated [CO2 ] (CO2e ) on the structure and function of plant hydraulic architecture and explore the implications of those changes using a model. Changes in conduit diameter and hydraulic conductance due to CO2e vary among species. Ring-porous species tend towards an increase in conduit size and consequently conductivity. The effect in diffuse-porous species is much more limited. In conifers, the results are mixed, some species show minor changes in xylem structure, while other studies found increases in tracheid density and diameter. Non-woody plants generally exhibited the reverse pattern with narrower conduits and lower hydraulic conductivity under CO2e . Further, changes in drought-resistance traits suggest that non-woody plants were the most affected by CO2e , which may permit them to better resist drought-induced embolism under future conditions. Due to their complexity, acclimation in hydraulic traits in response to CO2e is difficult to interpret when relying solely on measurements. When we examined how the observed tissues-specific trends might alter plant function, our modelling results suggest that these hydraulic changes would lead to reduced conductance and more frequent drought stress in trees that develop under CO2e with a more pronounced effect in isohydric than in anisohydric species.
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Affiliation(s)
- Jean-Christophe Domec
- Bordeaux Sciences Agro, UMR 1391 INRA-ISPA, 33175, Gradignan Cedex, France
- Nicholas School of the Environment, Duke University, Box 90328, Durham, NC, 27708, USA
| | - Duncan D Smith
- Department of Botany, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Kate A McCulloh
- Department of Botany, University of Wisconsin-Madison, Madison, WI, 53706, USA
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19
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Martínez-Sancho E, Dorado-Liñán I, Hacke UG, Seidel H, Menzel A. Contrasting Hydraulic Architectures of Scots Pine and Sessile Oak at Their Southernmost Distribution Limits. Front Plant Sci 2017; 8:598. [PMID: 28473841 PMCID: PMC5397420 DOI: 10.3389/fpls.2017.00598] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 04/03/2017] [Indexed: 05/05/2023]
Abstract
Many temperate European tree species have their southernmost distribution limits in the Mediterranean Basin. The projected climatic conditions, particularly an increase in dryness, might induce an altitudinal and latitudinal retreat at their southernmost distribution limit. Therefore, characterizing the morphological and physiological variability of temperate tree species under dry conditions is essential to understand species' responses to expected climate change. In this study, we compared branch-level hydraulic traits of four Scots pine and four sessile oak natural stands located at the western and central Mediterranean Basin to assess their adjustment to water limiting conditions. Hydraulic traits such as xylem- and leaf-specific maximum hydraulic conductivity (KS-MAX and KL-MAX), leaf-to-xylem area ratio (AL:AX) and functional xylem fraction (FX) were measured in July 2015 during a long and exceptionally dry summer. Additionally, xylem-specific native hydraulic conductivity (KS-N) and native percentage of loss of hydraulic conductivity (PLC) were measured for Scots pine. Interspecific differences in these hydraulic traits as well as intraspecific variability between sites were assessed. The influence of annual, summer and growing season site climatic aridity (P/PET) on intraspecific variability was investigated. Sessile oak displayed higher values of KS-MAX, KL-MAX, AL:AX but a smaller percentage of FX than Scots pines. Scots pine did not vary in any of the measured hydraulic traits across the sites, and PLC values were low for all sites, even during one of the warmest summers in the region. In contrast, sessile oak showed significant differences in KS-MAX, KL-MAX, and FX across sites, which were significantly related to site aridity. The striking similarity in the hydraulic traits across Scots pine sites suggests that no adjustment in hydraulic architecture was needed, likely as a consequence of a drought-avoidance strategy. In contrast, sessile oak displayed adjustments in the hydraulic architecture along an aridity gradient, pointing to a drought-tolerance strategy.
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Affiliation(s)
- Elisabet Martínez-Sancho
- Ecoclimatology, Department of Ecology and Ecosystem Management, Technische Universität MünchenFreising, Germany
| | - Isabel Dorado-Liñán
- Ecoclimatology, Department of Ecology and Ecosystem Management, Technische Universität MünchenFreising, Germany
- Departamento de Silvicultura y Gestión de los Sistemas Forestales, Centro de Investigación Forestal–Instituto Nacional de Investigación y Tecnología Agraria y AlimentariaMadrid, Spain
| | - Uwe G. Hacke
- Department of Renewable Resources, University of Alberta, EdmontonAB, Canada
| | - Hannes Seidel
- Ecoclimatology, Department of Ecology and Ecosystem Management, Technische Universität MünchenFreising, Germany
| | - Annette Menzel
- Ecoclimatology, Department of Ecology and Ecosystem Management, Technische Universität MünchenFreising, Germany
- Institute for Advanced Study, Technische Universität MünchenGarching, Germany
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20
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Zhang Z, Zhao P, McCarthy HR, Ouyang L, Niu J, Zhu L, Ni G, Huang Y. Hydraulic Balance of a Eucalyptus urophylla Plantation in Response to Periodic Drought in Low Subtropical China. Front Plant Sci 2016; 7:1346. [PMID: 27725821 PMCID: PMC5036442 DOI: 10.3389/fpls.2016.01346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Accepted: 08/22/2016] [Indexed: 06/06/2023]
Abstract
A clear understanding of hydraulic regulation in cultivated plants is crucial for addressing challenges to forest water cycling due to climate changes in low subtropical China. Experiments were conducted to determine the hydrologic balance of a Eucalyptus urophylla plantation in response to periodic drought. Trees displayed lower stomatal conductance (GS) and leaf water potentials (ΨL) during the dry periods. A decrease of 22.4% was found for the maximum reference GS (GS at D = 1 kPa; GSref-max). Accordingly, specific hydraulic conductivity (ks) decreased by 45.3 - 65.6% from the wet to the dry season, depending on the tree size. Fairly stable leaf stomatal conductance (gs) with decreasing ΨL (ΨL < -1.6 MPa) contributed to the high water-use efficiency (WUE) of this Eucalyptus species. Additionally, the lower stomatal sensitivity (-m = 0.53) in the dry season might also be responsible for the high WUE, since we found an anisohydric behavior that was associated with photosynthetically active radiation (Q0). Larger trees were found to use water more efficiently than small trees, due to the higher sensitivity of ks to decreasing ΨL. This was also verified by the decreasing leaf carbon isotope discrimination (Δ13C) with increasing tree diameter. However, further studies are needed to determine the universality of these results for other Eucalyptus species in this region.
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Affiliation(s)
- Zhenzhen Zhang
- Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Institute of Botany (CAS)Guangzhou, China
- College of Life Sciences, University of Chinese Academy of SciencesBeijing, China
| | - Ping Zhao
- Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Institute of Botany (CAS)Guangzhou, China
- Guangdong Provincial Key Laboratory of Applied Botany, South China Institute of Botany (CAS)Guangzhou, China
| | - Heather R. McCarthy
- Department of Microbiology and Plant Biology, University of Oklahoma, NormanOK, USA
| | - Lei Ouyang
- Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Institute of Botany (CAS)Guangzhou, China
| | - Junfeng Niu
- Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Institute of Botany (CAS)Guangzhou, China
| | - Liwei Zhu
- Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Institute of Botany (CAS)Guangzhou, China
| | - Guangyan Ni
- Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Institute of Botany (CAS)Guangzhou, China
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21
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Novick KA, Miniat CF, Vose JM. Drought limitations to leaf-level gas exchange: results from a model linking stomatal optimization and cohesion-tension theory. Plant Cell Environ 2016; 39:583-96. [PMID: 26466749 DOI: 10.1111/pce.12657] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2014] [Accepted: 09/14/2015] [Indexed: 05/23/2023]
Abstract
We merge concepts from stomatal optimization theory and cohesion-tension theory to examine the dynamics of three mechanisms that are potentially limiting to leaf-level gas exchange in trees during drought: (1) a 'demand limitation' driven by an assumption of optimal stomatal functioning; (2) 'hydraulic limitation' of water movement from the roots to the leaves; and (3) 'non-stomatal' limitations imposed by declining leaf water status within the leaf. Model results suggest that species-specific 'economics' of stomatal behaviour may play an important role in differentiating species along the continuum of isohydric to anisohydric behaviour; specifically, we show that non-stomatal and demand limitations may reduce stomatal conductance and increase leaf water potential, promoting wide safety margins characteristic of isohydric species. We used model results to develop a diagnostic framework to identify the most likely limiting mechanism to stomatal functioning during drought and showed that many of those features were commonly observed in field observations of tree water use dynamics. Direct comparisons of modelled and measured stomatal conductance further indicated that non-stomatal and demand limitations reproduced observed patterns of tree water use well for an isohydric species but that a hydraulic limitation likely applies in the case of an anisohydric species.
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Affiliation(s)
- Kimberly A Novick
- School of Public and Environmental Affairs, Indiana University, Bloomington, IN, 47405, USA
| | - Chelcy F Miniat
- USDA Forest Service, Coweeta Hydrologic Laboratory, Otto, NC, 28734, USA
| | - James M Vose
- USDA Forest Service - Southern Research Station - Center for Integrated Forest Science. North Carolina State University, Department of Forestry and Environmental Resources, Raleigh, NC, 27695-8008, USA
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22
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Moshelion M, Halperin O, Wallach R, Oren R, Way DA. Role of aquaporins in determining transpiration and photosynthesis in water-stressed plants: crop water-use efficiency, growth and yield. Plant Cell Environ 2015; 38:1785-93. [PMID: 25039365 DOI: 10.1111/pce.12410] [Citation(s) in RCA: 113] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Revised: 06/27/2014] [Accepted: 06/29/2014] [Indexed: 05/18/2023]
Abstract
The global shortage of fresh water is one of our most severe agricultural problems, leading to dry and saline lands that reduce plant growth and crop yield. Here we review recent work highlighting the molecular mechanisms allowing some plant species and genotypes to maintain productivity under water stress conditions, and suggest molecular modifications to equip plants for greater production in water-limited environments. Aquaporins (AQPs) are thought to be the main transporters of water, small and uncharged solutes, and CO2 through plant cell membranes, thus linking leaf CO2 uptake from the intercellular airspaces to the chloroplast with water loss pathways. AQPs appear to play a role in regulating dynamic changes of root, stem and leaf hydraulic conductivity, especially in response to environmental changes, opening the door to using AQP expression to regulate plant water-use efficiency. We highlight the role of vascular AQPs in regulating leaf hydraulic conductivity and raise questions regarding their role (as well as tonoplast AQPs) in determining the plant isohydric threshold, growth rate, fruit yield production and harvest index. The tissue- or cell-specific expression of AQPs is discussed as a tool to increase yield relative to control plants under both normal and water-stressed conditions.
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Affiliation(s)
- Menachem Moshelion
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Hebrew University of Jerusalem, Rehovot, 76100, Israel
| | - Ofer Halperin
- Department of Soil and Water Sciences, The Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, 76100, Israel
| | - Rony Wallach
- Department of Soil and Water Sciences, The Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, 76100, Israel
| | - Ram Oren
- Nicholas School of the Environment, Duke University, Durham, NC, 27708, USA
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU), SE-901 83, Umeå, Sweden
| | - Danielle A Way
- Nicholas School of the Environment, Duke University, Durham, NC, 27708, USA
- Department of Biology, Western University, London, ON, Canada, N6A5B7
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23
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Trifilò P, Nardini A, Lo Gullo MA, Barbera PM, Savi T, Raimondo F. Diurnal changes in embolism rate in nine dry forest trees: relationships with species-specific xylem vulnerability, hydraulic strategy and wood traits. Tree Physiol 2015; 35:694-705. [PMID: 26116926 DOI: 10.1093/treephys/tpv049] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 05/09/2015] [Indexed: 05/02/2023]
Abstract
Recent studies have reported correlations between stem sapwood capacitance (C(wood)) and xylem vulnerability to embolism, but it is unclear how C(wood) relates to the eventual ability of plants to reverse embolism. We investigated possible functional links between embolism reversal efficiency, C(wood), wood density (WD), vulnerability to xylem embolism and hydraulic safety margins in nine woody species native to dry sclerophyllous forests with different degrees of iso versus anisohydry. Substantial inter-specific differences in terms of seasonal/diurnal changes of xylem and leaf water potential, maximum diurnal values of transpiration rate and xylem vulnerability to embolism formation were recorded. Significant diurnal changes in percentage loss of hydraulic conductivity (PLC) were recorded for five species. Significant correlations were recorded between diurnal PLC changes and P50 and P88 values (i.e., xylem pressure inducing 50 and 88% PLC, respectively) as well as between diurnal PLC changes and safety margins referenced to P50 and P88. WD was linearly correlated with minimum diurnal leaf water potential, diurnal PLC changes and wood capacitance across all species. In contrast, significant relationships between P50, safety margin values referenced to P50 and WD were recorded only for the isohydric species. Functional links between diurnal changes in PLC, hydraulic strategies and WD and C(wood) are discussed.
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Affiliation(s)
- Patrizia Trifilò
- Dipartimento di Scienze Biologiche e Ambientali, Università di Messina, Salita F. Stagno D'Alcontres 31, 98166 Messina, Italy
| | - Andrea Nardini
- Dipartimento di Scienze della Vita, Università di Trieste, Via L. Giorgieri 10, 34127 Trieste, Italy
| | - Maria A Lo Gullo
- Dipartimento di Scienze Biologiche e Ambientali, Università di Messina, Salita F. Stagno D'Alcontres 31, 98166 Messina, Italy
| | - Piera M Barbera
- Dipartimento di Agraria, Università Mediterranea di Reggio Calabria, Feo di Vito, 89122 Reggio Calabria, Italy
| | - Tadeja Savi
- Dipartimento di Scienze della Vita, Università di Trieste, Via L. Giorgieri 10, 34127 Trieste, Italy
| | - Fabio Raimondo
- Dipartimento di Scienze Biologiche e Ambientali, Università di Messina, Salita F. Stagno D'Alcontres 31, 98166 Messina, Italy
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24
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Ambrose AR, Baxter WL, Wong CS, Næsborg RR, Williams CB, Dawson TE. Contrasting drought-response strategies in California redwoods. Tree Physiol 2015; 35:453-469. [PMID: 25787330 DOI: 10.1093/treephys/tpv016] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Accepted: 01/30/2015] [Indexed: 06/04/2023]
Abstract
We compared the physiology and growth of seedlings originating from different Sequoia sempervirens (D. Don.) Endl. (coast redwood) and Sequoiadendron giganteum (Lindl.) Buchh. (giant sequoia) populations subjected to progressive drought followed by a recovery period in a controlled greenhouse experiment. Our objective was to examine how multiple plant traits interact to influence the response of seedlings of each species and seed population to a single drought and recovery cycle. We measured soil and plant water status, leaf gas exchange, stem embolism and growth of control (well-watered) and drought-stressed (water withheld) seedlings from each population at the beginning, middle and end of a 6-week drought period and again 2 weeks after re-watering. The drought had a significant effect on many aspects of seedling performance, but water-stressed seedlings regained most physiological functioning by the end of the recovery period. Sequoiadendron seedlings exhibited a greater degree of isohydry (water status regulation), lower levels of stem embolism, higher biomass allocation to roots and lower sensitivity of growth to drought compared with Sequoia. Only minor intra-specific differences were observed among populations. Our results show that seedlings of the two redwood species exhibit contrasting drought-response strategies that align with the environmental conditions these trees experience in their native habitats, and demonstrate trade-offs and coordination among traits affecting plant water use, carbon gain and growth under drought.
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Affiliation(s)
- Anthony R Ambrose
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
| | - Wendy L Baxter
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
| | - Christopher S Wong
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
| | - Rikke R Næsborg
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
| | - Cameron B Williams
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
| | - Todd E Dawson
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
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25
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Dickman LT, McDowell NG, Sevanto S, Pangle RE, Pockman WT. Carbohydrate dynamics and mortality in a piñon-juniper woodland under three future precipitation scenarios. Plant Cell Environ 2015; 38:729-39. [PMID: 25159277 DOI: 10.1111/pce.12441] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Accepted: 08/07/2014] [Indexed: 05/16/2023]
Abstract
Drought-induced forest mortality is an increasing global problem with wide-ranging consequences, yet mortality mechanisms remain poorly understood. Depletion of non-structural carbohydrate (NSC) stores has been implicated as an important mechanism in drought-induced mortality, but experimental field tests are rare. We used an ecosystem-scale precipitation manipulation experiment to evaluate leaf and twig NSC dynamics of two co-occurring conifers that differ in patterns of stomatal regulation of water loss and recent mortality: the relatively desiccation-avoiding piñon pine (Pinus edulis) and the relatively desiccation-tolerant one-seed juniper (Juniperus monosperma). Piñon pine experienced 72% mortality after 13-25 months of experimental drought and juniper experienced 20% mortality after 32-47 months. Juniper maintained three times more NSC in the foliage than twigs, and converted NSC to glucose and fructose under drought, consistent with osmoregulation requirements to maintain higher stomatal conductance during drought than piñon. Despite these species differences, experimental drought caused decreased leaf starch content in dying trees of both species (P < 0.001). Average dry-season leaf starch content was also a good predictor of drought-survival time for both species (R(2) = 0.93). These results, along with observations of drought-induced reductions to photosynthesis and growth, support carbon limitation as an important process during mortality of these two conifer species.
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Affiliation(s)
- Lee T Dickman
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
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26
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Franklin O, Palmroth S, Näsholm T. How eco-evolutionary principles can guide tree breeding and tree biotechnology for enhanced productivity. Tree Physiol 2014; 34:1149-1166. [PMID: 25542897 DOI: 10.1093/treephys/tpu111] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Tree breeding and biotechnology can enhance forest productivity and help alleviate the rising pressure on forests from climate change and human exploitation. While many physiological processes and genes are targeted in search of genetically improved tree productivity, an overarching principle to guide this search is missing. Here, we propose a method to identify the traits that can be modified to enhance productivity, based on the differences between trees shaped by natural selection and 'improved' trees with traits optimized for productivity. We developed a tractable model of plant growth and survival to explore such potential modifications under a range of environmental conditions, from non-water limited to severely drought-limited sites. We show how key traits are controlled by a trade-off between productivity and survival, and that productivity can be increased at the expense of long-term survival by reducing isohydric behavior (stomatal regulation of leaf water potential) and allocation to defense against pests compared with native trees. In contrast, at dry sites occupied by naturally drought-resistant trees, the model suggests a better strategy may be to select trees with slightly lower wood density than the native trees and to augment isohydric behavior and allocation to defense. Thus, which traits to modify, and in which direction, depend on the original tree species or genotype, the growth environment and wood-quality versus volume production preferences. In contrast to this need for customization of drought and pest resistances, consistent large gains in productivity for all genotypes can be obtained if root traits can be altered to reduce competition for water and nutrients. Our approach illustrates the potential of using eco-evolutionary theory and modeling to guide plant breeding and genetic technology in selecting target traits in the quest for higher forest productivity.
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Affiliation(s)
- Oskar Franklin
- Ecosystems Services and Management Program , International Institute for Applied Systems Analysis, A-2361 Laxenburg , Austria;
| | - Sari Palmroth
- Nicholas School of the Environment and Earth Sciences, Duke University, Durham, NC 27708 , USA
| | - Torgny Näsholm
- Department of Forest Ecology and Management , Swedish University of Agricultural Sciences, SE-901 83 Umeå , Sweden; Department of Forest Genetics and Plant Physiology , Umeå Plant Science Centre, Swedish University of Agricultural Sciences, SE-901 85 Umeå , Sweden
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27
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Abstract
Water scarcity is a critical limitation for agricultural systems. Two different water management strategies have evolved in plants: an isohydric strategy and an anisohydric strategy. Isohydric plants maintain a constant midday leaf water potential (Ψleaf) when water is abundant, as well as under drought conditions, by reducing stomatal conductance as necessary to limit transpiration. Anisohydric plants have more variable Ψleaf and keep their stomata open and photosynthetic rates high for longer periods, even in the presence of decreasing leaf water potential. This risk-taking behavior of anisohydric plants might be beneficial when water is abundant, as well as under moderately stressful conditions. However, under conditions of intense drought, this behavior might endanger the plant. We will discuss the advantages and disadvantages of these two water-usage strategies and their effects on the plant's ability to tolerate abiotic and biotic stress. The involvement of plant tonoplast AQPs in this process will also be discussed.
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Affiliation(s)
- Nir Sade
- Faculty of Agriculture; Food and Environment; The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture; The Hebrew University of Jerusalem; Rehovot, Israel
| | - Alem Gebremedhin
- Faculty of Agriculture; Food and Environment; The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture; The Hebrew University of Jerusalem; Rehovot, Israel
| | - Menachem Moshelion
- Faculty of Agriculture; Food and Environment; The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture; The Hebrew University of Jerusalem; Rehovot, Israel
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