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Marino G, Guzmán-Delgado P, Santos E, Adaskaveg JA, Blanco-Ulate B, Ferguson L, Zwieniecki MA, Fernández-Suela E. Interactive effect of branch source-sink ratio and leaf aging on photosynthesis in pistachio. Front Plant Sci 2023; 14:1194177. [PMID: 37600173 PMCID: PMC10436215 DOI: 10.3389/fpls.2023.1194177] [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] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Accepted: 06/27/2023] [Indexed: 08/22/2023]
Abstract
Tree source-sink ratio has a predominant and complex impact on tree performance and can affect multiple physiological processes including vegetative and reproductive growth, water and nutrient use, photosynthesis, and productivity. In this study, we manipulated the branch level source-sink ratio by reduction of photosynthetic activity (partial branch defoliation) or thinning branch fruit load early in the growing season (after fruit set) in pistachio (Pistacia vera) trees. We then characterized the leaf photosynthetic light response curves through leaf aging. In addition, we determined changes in leaf non-structural carbohydrates (NSC) and nitrogen (N) concentrations. In leaves with high source-sink ratios, there was a gradual decrease in maximum net photosynthetic rate (ANmax) over the growing season, while in branches with low source-sink ratios, there was a sharp decline in ANmax in the first two weeks of August. Branches with high-sink showed an up-regulation (increase) in photosynthesis toward the end of July (at 1,500 growing degree days) during the period of rapid kernel growth rate and increased sink strength, with ANmax being about 7 μmol m-1 s-1 higher than in branches with low-sink. In August, low source-sink ratios precipitated leaf senescence, resulting in a drastic ANmax decline, from 25 to 8 μmol m-1 s-1 (70% drop in two weeks). This reduction was associated with the accumulation of NSC in the leaves from 20 to 30 mg g-1. The mechanisms of ANmax reduction differ between the two treatments. Lower photosynthetic rates of 8-10 μmol m-1 s-1 late in the season were associated with lower N levels in high-sink branches, suggesting N remobilization to the kernels. Lower photosynthesis late in the season was associated with lower respiration rates in low-source branches, indicating prioritization of assimilates to storage. These results can facilitate the adaptation of management practices to tree crop load changes in alternate bearing species.
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Affiliation(s)
- Giulia Marino
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
| | - Paula Guzmán-Delgado
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
| | - Emily Santos
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
| | - Jaclyn A. Adaskaveg
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
| | - Bárbara Blanco-Ulate
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
| | - Louise Ferguson
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
| | - Maciej A. Zwieniecki
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
| | - Eduardo Fernández-Suela
- Instituto Madrileño de Investigación y Desarrollo Rural, Agrario y Alimentario, Madrid, Spain
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2
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Chin ARO, Guzmán-Delgado P, Görlich A, HilleRisLambers J. Towards multivariate functional trait syndromes: Predicting foliar water uptake in trees. Ecology 2023; 104:e4112. [PMID: 37252804 DOI: 10.1002/ecy.4112] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 05/10/2023] [Accepted: 05/18/2023] [Indexed: 06/01/2023]
Abstract
Analysis of functional traits is a cornerstone of ecology, yet individual traits seldom explain useful amounts of variation in species distribution or climatic tolerance, and their functional significance is rarely validated experimentally. Multivariate suites of interacting traits could build an understanding of ecological processes and improve our ability to make sound predictions of species success in our rapidly changing world. We use foliar water uptake capacity as a case study because it is increasingly considered to be a key functional trait in plant ecology due to its importance for stress-tolerance physiology. However, the traits behind the trait, that is, the features of leaves that determine variation in foliar water uptake rates, have not been assembled into a widely applicable framework for uptake prediction. Focusing on trees, we investigated relationships among 25 structural traits, leaf osmotic potential (a source of free energy to draw water into leaves), and foliar water uptake in 10 diverse angiosperm and conifer species. We identified consistent, multitrait "uptake syndromes" for both angiosperm and conifer trees, with differences in key traits revealing suspected differences in the water entry route between these two clades and an evolutionarily significant divergence in the function of homologous structures. A literature review of uptake-associated functional traits, which largely documents similar univariate relationships, provides additional support for our proposed "uptake syndrome." Importantly, more than half of shared traits had opposite-direction influences on the capacity of leaves to absorb water in angiosperms and conifers. Taxonomically targeted multivariate trait syndromes provide a useful tool for trait selection in ecological research, while highlighting the importance of micro-traits and the physiological verification of their function for advancing trait-based ecology.
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Affiliation(s)
- Alana R O Chin
- Plant Ecology Group, Institute of Integrative Biology, ETH-Zürich, Zürich, Switzerland
| | - Paula Guzmán-Delgado
- Department of Plant Sciences, University of California, Davis, Davis, California, USA
| | - Anna Görlich
- Plant Ecology Group, Institute of Integrative Biology, ETH-Zürich, Zürich, Switzerland
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3
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Chin ARO, Guzmán-Delgado P, Kerhoulas LP, Zwieniecki MA. Acclimation of interacting leaf surface traits affects foliar water uptake. Tree Physiol 2023; 43:418-429. [PMID: 36222161 DOI: 10.1093/treephys/tpac120] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [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: 06/03/2022] [Revised: 10/02/2022] [Accepted: 10/08/2022] [Indexed: 05/03/2023]
Abstract
Absorption of water across the surfaces of leaves is an ecologically important aspect of tree physiology. Variation in foliar water uptake capacity depends on environmental conditions when traits associated with the uptake pathway respond to climatic signals. Using a series of experiments, we verify that water enters Sequoia sempervirens (D. Don) Endl. leaves by crossing the cuticle, and show that surface-trait acclimation alters the kinetic parameters of foliar water uptake. Under our experimental conditions, the cuticle was the primary pathway for water entry into the leaf. Exposure to climatic variation may induce surface acclimations, such as increased waxiness, that reduce water-film formation over stomata at the expense of dry-season foliar uptake rates. We found that water uptake is negatively associated with the interaction of leaf-surface wax coverage and stomatal density, and provide an accessible protocol to measure these key traits in Sequoia. Linking absorptive pathways and trait acclimation to physiological performance can provide a foundation for range-wide or genomic investigations of forest interactions with water and a mechanism-centered means to monitor canopy hydraulic parameters over time.
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Affiliation(s)
- Alana R O Chin
- Plant Sciences Department, University of California Davis, Davis, CA 95616, USA
- Institute of Integrative Biology, Plant Ecology Group, ETH, Zürich, 8092, Switzerland
| | | | - Lucy P Kerhoulas
- Department of Forestry and Wildland Resources, California Polytechnic Institute, Arcata, CA 95521, USA
| | - Maciej A Zwieniecki
- Plant Sciences Department, University of California Davis, Davis, CA 95616, USA
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Chin ARO, Guzmán-Delgado P, Sillett SC, Kerhoulas LP, Ambrose AR, McElrone AR, Zwieniecki MA. Tracheid buckling buys time, foliar water uptake pays it back: Coordination of leaf structure and function in tall redwood trees. Plant Cell Environ 2022; 45:2607-2616. [PMID: 35736139 DOI: 10.1111/pce.14381] [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] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 06/19/2022] [Indexed: 06/15/2023]
Abstract
Tracheid buckling may protect leaves in the dynamic environments of forest canopies, where rapid intensifications of evaporative demand, such as those brought on by changes in light availability, can result in sudden increases in transpiration rate. While treetop leaves function in reliably direct light, leaves below the upper crown must tolerate rapid, thermally driven increases in evaporative demand. Using synchrotron-based X-ray microtomography, we visualized impacts of experimentally induced water stress and subsequent fogging on living cells in redwood leaves, adding ecological and functional context through crown-wide explorations of variation in leaf physiology and microclimate. Under drought, leaf transfusion tracheids buckle, releasing water that supplies sufficient temporal reserves for leaves to reduce stomatal conductance safely while stopping the further rise of tension. Tracheid buckling fraction decreases with height and is closely coordinated with transfusion tissue capacity and stomatal conductance to provide temporal reserves optimized for local variation in microclimate. Foliar water uptake fully restores collapsed and air-filled transfusion tracheids in leaves on excised shoots, suggesting that trees may use aerial water sources for recovery. In the intensely variable deep-crown environment, foliar water uptake can allow for repetitive cycles of tracheid buckling and unbuckling, protecting the tree from damaging levels of hydraulic tension and supporting leaf survival.
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Affiliation(s)
- Alana R O Chin
- Department of Plant Sciences, University of California Davis, Davis, California, USA
| | - Paula Guzmán-Delgado
- Department of Plant Sciences, University of California Davis, Davis, California, USA
| | - Stephen C Sillett
- Department of Forestry and Wildland Resources, Humboldt State University, Arcata, California, USA
| | - Lucy P Kerhoulas
- Department of Forestry and Wildland Resources, Humboldt State University, Arcata, California, USA
| | - Anthony R Ambrose
- Department of Integrative Biology, University of California Berkeley, Berkeley, California, USA
| | - Andrew R McElrone
- USDA-ARS & Viticulture and Enology Department, University of California Davis, Davis, California, USA
| | - Maciej A Zwieniecki
- Department of Plant Sciences, University of California Davis, Davis, California, USA
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Amico Roxas A, Orozco J, Guzmán-Delgado P, Zwieniecki MA. Spring phenology is affected by fall non-structural carbohydrate concentration and winter sugar redistribution in three Mediterranean nut tree species. Tree Physiol 2021; 41:1425-1438. [PMID: 34383074 DOI: 10.1093/treephys/tpab014] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [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: 07/03/2020] [Accepted: 01/26/2021] [Indexed: 06/13/2023]
Abstract
Deciduous trees mostly rely on non-structural carbohydrates (NSC-soluble carbohydrates and starch) stored prior to dormancy to sustain both spring bloom and the initial phase of spring growth prior to the transition of leaves from sink to source. Winter management of NSC, their loss due to respiration, reallocation patterns and remobilization during spring, seems to be key to a timely and synchronous bloom. To assess tree dependence on NSC during dormancy, we tested whether the interruption of local branch NSC accumulation prior to dormancy by defoliation and the interruption of NSC translocation by phloem girdling influence spring phenology in three major deciduous Mediterranean nut crop species: Prunus dulcis (Mill.) D.A Webb, a hybrid between Pistacia integerrima (J. L. Stewart ex Brandis) and P. atlantica Desf. (referred to as P. integerrima), and Juglans regia L. Defoliation treatments had different effects on NSC concentration in different species depending on the time of application. However, despite the significant initial impact (increase or decrease of NSC concentration), with time this impact diminished resulting in overall similar concentrations between control and defoliated branches suggesting the presence of NSC reallocation during dormancy. Phloem girdling in P. dulcis and P. integerrima resulted in reduced export activity and greater NSC concentrations, while in J. regia girdling resulted in lower NSC concentrations, indicating that this species requires a net import of NSC during dormancy. Bud break was distinctly delayed by both defoliation and phloem girdling in all the three species, providing evidence of the significant roles that fall NSC accumulation and winter NSC management play in priming trees for spring growth resumption.
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Affiliation(s)
- Adele Amico Roxas
- Department of Plant Sciences, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Jessica Orozco
- Department of Plant Sciences, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Paula Guzmán-Delgado
- Department of Plant Sciences, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Maciej A Zwieniecki
- Department of Plant Sciences, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
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Guzmán-Delgado P, Laca E, Zwieniecki MA. Unravelling foliar water uptake pathways: The contribution of stomata and the cuticle. Plant Cell Environ 2021; 44:1728-1740. [PMID: 33665817 DOI: 10.1111/pce.14041] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [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: 08/08/2020] [Revised: 02/26/2021] [Accepted: 03/01/2021] [Indexed: 06/12/2023]
Abstract
Plants can absorb water through their leaf surfaces, a phenomenon commonly referred to as foliar water uptake (FWU). Despite the physiological importance of FWU, the pathways and mechanisms underlying the process are not well known. Using a novel experimental approach, we parsed out the contribution of the stomata and the cuticle to FWU in two species with Mediterranean (Prunus dulcis) and temperate (Pyrus communis) origin. The hydraulic parameters of FWU were derived by analysing mass and water potential changes of leaves placed in a fog chamber. Leaves were previously treated with abscisic acid to force stomata to remain closed, with fusicoccin to remain open, and with water (control). Leaves with open stomata rehydrated two times faster than leaves with closed stomata and attained approximately three times higher maximum fluxes and hydraulic conductance. Based on FWU rates, we propose that rehydration through stomata occurs primarily via diffusion of water vapour rather than in liquid form even when leaf surfaces are covered with a water film. We discuss the potential mechanisms of FWU and the significance of both stomatal and cuticular pathways for plant productivity and survival.
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Affiliation(s)
- Paula Guzmán-Delgado
- Department of Plant Sciences, University of California Davis, Davis, California, USA
| | - Emilio Laca
- Department of Plant Sciences, University of California Davis, Davis, California, USA
| | - Maciej A Zwieniecki
- Department of Plant Sciences, University of California Davis, Davis, California, USA
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7
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Marino G, Scalisi A, Guzmán-Delgado P, Caruso T, Marra FP, Lo Bianco R. Detecting Mild Water Stress in Olive with Multiple Plant-Based Continuous Sensors. Plants (Basel) 2021; 10:131. [PMID: 33440632 PMCID: PMC7827840 DOI: 10.3390/plants10010131] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 12/31/2020] [Accepted: 01/08/2021] [Indexed: 02/07/2023]
Abstract
A comprehensive characterization of water stress is needed for the development of automated irrigation protocols aiming to increase olive orchard environmental and economical sustainability. The main aim of this study is to determine whether a combination of continuous leaf turgor, fruit growth, and sap flow responses improves the detection of mild water stress in two olive cultivars characterized by different responses to water stress. The sensitivity of the tested indicators to mild stress depended on the main mechanisms that each cultivar uses to cope with water deficit. One cultivar showed pronounced day to day changes in leaf turgor and fruit relative growth rate in response to water withholding. The other cultivar reduced daily sap flows and showed a pronounced tendency to reach very low values of leaf turgor. Based on these responses, the sensitivity of the selected indicators is discussed in relation to drought response mechanisms, such as stomatal closure, osmotic adjustment, and tissue elasticity. The analysis of the daily dynamics of the monitored parameters highlights the limitation of using non-continuous measurements in drought stress studies, suggesting that the time of the day when data is collected has a great influence on the results and consequent interpretations, particularly when different genotypes are compared. Overall, the results highlight the need to tailor plant-based water management protocols on genotype-specific physiological responses to water deficit and encourage the use of combinations of plant-based continuously monitoring sensors to establish a solid base for irrigation management.
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Affiliation(s)
- Giulia Marino
- Department of Plant Sciences, University of California, Davis, CA 95616, USA;
- Department of Agricultural, Food and Forest Sciences (SAAF), University of Palermo, 90133 Palermo, Italy; (A.S.); (T.C.); (F.P.M.)
| | - Alessio Scalisi
- Department of Agricultural, Food and Forest Sciences (SAAF), University of Palermo, 90133 Palermo, Italy; (A.S.); (T.C.); (F.P.M.)
- Agriculture Victoria, Department of Jobs, Precincts and Regions, Tatura, VIC 3616, Australia
| | | | - Tiziano Caruso
- Department of Agricultural, Food and Forest Sciences (SAAF), University of Palermo, 90133 Palermo, Italy; (A.S.); (T.C.); (F.P.M.)
| | - Francesco Paolo Marra
- Department of Agricultural, Food and Forest Sciences (SAAF), University of Palermo, 90133 Palermo, Italy; (A.S.); (T.C.); (F.P.M.)
| | - Riccardo Lo Bianco
- Department of Agricultural, Food and Forest Sciences (SAAF), University of Palermo, 90133 Palermo, Italy; (A.S.); (T.C.); (F.P.M.)
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8
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Godfrey JM, Riggio J, Orozco J, Guzmán-Delgado P, Chin ARO, Zwieniecki MA. Ray fractions and carbohydrate dynamics of tree species along a 2750 m elevation gradient indicate climate response, not spatial storage limitation. New Phytol 2020; 225:2314-2330. [PMID: 31808954 DOI: 10.1111/nph.16361] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [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: 08/16/2019] [Accepted: 11/03/2019] [Indexed: 06/10/2023]
Abstract
Parenchyma cells in the xylem store nonstructural carbohydrates (NSC), providing reserves of energy that fuel woody perennials through periods of stress and/or limitations to photosynthesis. If the capacity for storage is subject to selection, then the fraction of wood occupied by living parenchyma should increase towards stressful environments. Ray parenchyma fraction (RPF) and seasonal NSC dynamics were quantified for 12 conifers and three oaks along a transect spanning warm dry foothills (500 m above sea level) to cold wet treeline (3250 m asl) in California's central Sierra Nevada. Mean RPF was lower for both conifer and oak species with warmer dryer ranges. RPF variability increased with elevation or in relation to associated climatic variables in conifers - treeline-dominant Pinus albicaulis had the lowest mean RPF measured (c. 3.7%), but the highest environmentally standardized variability index. Conifer RPF variability was explained by environment, increasing predominantly towards cooler wetter range edges. In oaks, NSC was explained by environment - values increasing for evergreen and decreasing for deciduous oaks with elevation. Lastly, all species surveyed appear to prioritize filling available RPF with sugar to achieve molarities that balance reasonable tensions over starch to maximize stored carbon. RPF responds to environment but is unlikely to spatially constrain NSC storage.
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Affiliation(s)
- Jessie M Godfrey
- Plant Sciences Department, University of California, Davis, CA, 95616, USA
| | - Jason Riggio
- Department of Wildlife, Fish, & Conservation Biology, University of California, Davis, CA, 95616, USA
| | - Jessica Orozco
- Plant Sciences Department, University of California, Davis, CA, 95616, USA
| | | | - Alana R O Chin
- Plant Sciences Department, University of California, Davis, CA, 95616, USA
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9
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Tixier A, Guzmán-Delgado P, Sperling O, Amico Roxas A, Laca E, Zwieniecki MA. Comparison of phenological traits, growth patterns, and seasonal dynamics of non-structural carbohydrate in Mediterranean tree crop species. Sci Rep 2020; 10:347. [PMID: 31941910 PMCID: PMC6962427 DOI: 10.1038/s41598-019-57016-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Accepted: 12/02/2019] [Indexed: 11/20/2022] Open
Abstract
Despite non-structural carbohydrate (NSC) importance for tree productivity and resilience, little is known about their seasonal regulations and trade-off with growth and reproduction. We characterize the seasonal dynamics of NSC in relation to the aboveground phenology and temporal growth patterns of three deciduous Mediterranean species: almond (Prunus dulcis (Mill.) D. A. Webb), walnut (Juglans regia L.) and pistachio (Pistacia vera L.). Seasonal dynamics of NSC were synchronous between wood tissues from trunk, branches and twigs. Almond had almost identical levels and patterns of NSC variation in twigs, branches and trunks whereas pistachio and walnut exhibited clear concentration differences among plant parts whereby twigs had the highest and most variable NSC concentration, followed by branches and then trunk. While phenology had a significant influence on NSC seasonal trends, there was no clear trade-off between NSC storage and growth suggesting that both were similarly strong sinks for NSC. A temporal trade-off observed at the seasonal scale was influenced by the phenology of the species. We propose that late senescing species experience C allocation trade-off at the end of the growing season because of C-limiting thermal conditions and priority allocation to storage in order to survive winter.
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Affiliation(s)
- Aude Tixier
- UMR 1347 Agroécologie, AgroSup/INRA/uB, Dijon, France.
| | | | - Or Sperling
- Department of Plant Sciences, Agriculture Research Organization (ARO), Negev, Israel
| | - Adele Amico Roxas
- Department of Plant Sciences, University of California, Davis, CA, USA
| | - Emilio Laca
- Department of Plant Sciences, University of California, Davis, CA, USA
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Guzmán-Delgado P, Zwieniecki MA. The makeup of a gamete space capsule. Nat Plants 2019; 5:8. [PMID: 30559415 DOI: 10.1038/s41477-018-0342-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Affiliation(s)
| | - Maciej A Zwieniecki
- Department of Plant Sciences, University of California Davis, Davis, CA, USA
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11
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Guzmán-Delgado P, Mason Earles J, Zwieniecki MA. Insight into the physiological role of water absorption via the leaf surface from a rehydration kinetics perspective. Plant Cell Environ 2018; 41:1886-1894. [PMID: 29740843 DOI: 10.1111/pce.13327] [Citation(s) in RCA: 6] [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: 10/12/2017] [Accepted: 04/24/2018] [Indexed: 06/08/2023]
Abstract
Soil water transported via the petiole is a primary rehydration pathway for leaves of water-stressed plants. Leaves may also rehydrate by absorbing water via their epidermal surfaces. The mechanisms and physiological relevance of this water pathway, however, remain unclear, as the associated hydraulic properties are unknown. To gain insight into the foliar water absorption process, we compared rehydration kinetics via the petiole and surface of Prunus dulcis and Quercus lobata leaves. Petiole rehydration could be described by a double exponential function suggesting that 2 partly isolated water pools exist in leaves of both species. Surface rehydration could be described by a logistic function, suggesting that leaves behave as a single water pool. Whereas full leaf rehydration via the petiole required approximately 20 min, it took over 150 and 300 min via the surface of P. dulcis and Q. lobata, respectively. Such differences were attributed to the high resistance imposed by the leaf surface and especially the cuticle. The minimum resistance to surface rehydration was estimated to be 6.6 × 102 (P. dulcis) and 2.6 × 103 MPa·m2 ·s·g-1 (Q. lobata), which is remarkably higher than estimated for petiole rehydration. These results are discussed in a physiological context.
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Affiliation(s)
- Paula Guzmán-Delgado
- Department of Plant Sciences, University of California Davis, Davis, CA, 95616, USA
| | - J Mason Earles
- School of Forestry & Environmental Studies, Yale University, New Haven, CT, 06511, USA
| | - Maciej A Zwieniecki
- Department of Plant Sciences, University of California Davis, Davis, CA, 95616, USA
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12
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Guzmán-Delgado P, Fernández V, Venturas M, Rodríguez-Calcerrada J, Gil L. Surface properties and physiology of Ulmus laevis and U. minor samaras: implications for seed development and dispersal. Tree Physiol 2017; 37:815-826. [PMID: 28369592 DOI: 10.1093/treephys/tpx022] [Citation(s) in RCA: 5] [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: 08/11/2016] [Accepted: 02/28/2017] [Indexed: 05/29/2023]
Abstract
Plant surface properties influence solid-liquid interactions and matter exchange between the organs and their surrounding environment. In the case of fruits, surface processes may be of relevance for seed production and dispersal. To gain insight into the relationship between surface structure, chemical composition and function of aerial reproductive organs, we performed diverse experiments with the dry, winged fruits, or samaras, of Ulmus laevis Pall. and Ulmus minor Mill. both at the time of full maturity (green samaras) and of samara dispersal (dry samaras). Samaras of both elm species showed positive photosynthetic rates and absorbed water through their epidermal surfaces. The surface wettability, free energy, polarity and solubility parameter were lower in U. laevis than in U. minor and decreased for dry samaras in both species. Ulmus laevis samaras had a high degree of surface nano-roughness mainly conferred by cell wall folds containing pectins that substantially increased after hydration. The samaras in this species also had a thicker cuticle that could be isolated by enzymatic digestion, whereas that of U. minor samaras had higher amounts of soluble lipids. Dry samaras of U. laevis had higher floatability and lower air sustentation than those of U. minor. We concluded that samaras contribute to seed development by participating in carbon and water exchange. This may be especially important for U. minor, whose samaras develop before leaf emergence. The trichomes present along U. laevis samara margin may enhance water absorption and samara floatability even in turbulent waters. In general, U. minor samaras show traits that are consistent with a more drought tolerant character than U. laevis samaras, in line with the resources available both at the tree and ecosystem level for these species. Samara features may additionally reflect different adaptive strategies for seed dispersal and niche differentiation between species, by favoring hydrochory for U. laevis and anemochory for U. minor.
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Affiliation(s)
- Paula Guzmán-Delgado
- Forest Genetics and Ecophysiology Research Group, School of Forest Engineering, Technical University of Madrid, Ciudad Universitaria, Madrid 28040, Spain
- Department of Plant Sciences, University of California Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Victoria Fernández
- Forest Genetics and Ecophysiology Research Group, School of Forest Engineering, Technical University of Madrid, Ciudad Universitaria, Madrid 28040, Spain
| | - Martin Venturas
- Forest Genetics and Ecophysiology Research Group, School of Forest Engineering, Technical University of Madrid, Ciudad Universitaria, Madrid 28040, Spain
- Department of Biology, University of Utah, 257 South 1400 East, Salt Lake City, UT 84112, USA
| | - Jesús Rodríguez-Calcerrada
- Forest Genetics and Ecophysiology Research Group, School of Forest Engineering, Technical University of Madrid, Ciudad Universitaria, Madrid 28040, Spain
| | - Luis Gil
- Forest Genetics and Ecophysiology Research Group, School of Forest Engineering, Technical University of Madrid, Ciudad Universitaria, Madrid 28040, Spain
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Guzmán-Delgado P, Graça J, Cabral V, Gil L, Fernández V. The presence of cutan limits the interpretation of cuticular chemistry and structure: Ficus elastica leaf as an example. Physiol Plant 2016; 157:205-20. [PMID: 26756450 DOI: 10.1111/ppl.12414] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 10/21/2015] [Accepted: 11/17/2015] [Indexed: 05/02/2023]
Abstract
Plant cuticles have been traditionally classified on the basis of their ultrastructure, with certain chemical composition assumptions. However, the nature of the plant cuticle may be misinterpreted in the prevailing model, which was established more than 150 years ago. Using the adaxial leaf cuticle of Ficus elastica, a study was conducted with the aim of analyzing cuticular ultrastructure, chemical composition and the potential relationship between structure and chemistry. Gradual chemical extractions and diverse analytical and microscopic techniques were performed on isolated leaf cuticles of two different stages of development (i.e. young and mature leaves). Evidence for the presence of cutan in F. elastica leaf cuticles has been gained after chemical treatments and tissue analysis by infrared spectroscopy and electron microscopy. Significant calcium, boron and silicon concentrations were also measured in the cuticle of this species. Such mineral elements which are often found in plant cell walls may play a structural role and their presence in isolated cuticles further supports the interpretation of the cuticle as the most external region of the epidermal cell wall. The complex and heterogeneous nature of the cuticle, and constraints associated with current analytical procedures may limit the chance for establishing a relationship between cuticle chemical composition and structure also in relation to organ ontogeny.
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Affiliation(s)
- Paula Guzmán-Delgado
- Forest Genetics and Ecophysiology Research Group, School of Forest Engineering, Technical University of Madrid, Madrid, Spain
| | - José Graça
- Instituto Superior de Agronomia, Centro de Estudos Florestais, Universidade de Lisboa, Lisboa, Portugal
| | - Vanessa Cabral
- Instituto Superior de Agronomia, Centro de Estudos Florestais, Universidade de Lisboa, Lisboa, Portugal
| | - Luis Gil
- Forest Genetics and Ecophysiology Research Group, School of Forest Engineering, Technical University of Madrid, Madrid, Spain
| | - Victoria Fernández
- Forest Genetics and Ecophysiology Research Group, School of Forest Engineering, Technical University of Madrid, Madrid, Spain
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Fernández V, Guzmán-Delgado P, Graça J, Santos S, Gil L. Cuticle Structure in Relation to Chemical Composition: Re-assessing the Prevailing Model. Front Plant Sci 2016; 7:427. [PMID: 27066059 PMCID: PMC4814898 DOI: 10.3389/fpls.2016.00427] [Citation(s) in RCA: 110] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 03/18/2016] [Indexed: 05/18/2023]
Abstract
The surface of most aerial plant organs is covered with a cuticle that provides protection against multiple stress factors including dehydration. Interest on the nature of this external layer dates back to the beginning of the 19th century and since then, several studies facilitated a better understanding of cuticular chemical composition and structure. The prevailing undertanding of the cuticle as a lipidic, hydrophobic layer which is independent from the epidermal cell wall underneath stems from the concept developed by Brongniart and von Mohl during the first half of the 19th century. Such early investigations on plant cuticles attempted to link chemical composition and structure with the existing technologies, and have not been directly challenged for decades. Beginning with a historical overview about the development of cuticular studies, this review is aimed at critically assessing the information available on cuticle chemical composition and structure, considering studies performed with cuticles and isolated cuticular chemical components. The concept of the cuticle as a lipid layer independent from the cell wall is subsequently challenged, based on the existing literature, and on new findings pointing toward the cell wall nature of this layer, also providing examples of different leaf cuticle structures. Finally, the need for a re-assessment of the chemical and structural nature of the plant cuticle is highlighted, considering its cell wall nature and variability among organs, species, developmental stages, and biotic and abiotic factors during plant growth.
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Affiliation(s)
- Victoria Fernández
- Forest Genetics and Ecophysiology Research Group, Plant Physiology and Anatomy Unit, School of Forest Engineering, Technical University of MadridMadrid, Spain
| | - Paula Guzmán-Delgado
- Forest Genetics and Ecophysiology Research Group, Plant Physiology and Anatomy Unit, School of Forest Engineering, Technical University of MadridMadrid, Spain
- Department of Plant Sciences, University of California, Davis, DavisCA, USA
| | - José Graça
- Centro de Estudos Florestais, Instituto Superior de Agronomia, Universidade de LisboaLisboa, Portugal
| | - Sara Santos
- Centro de Estudos Florestais, Instituto Superior de Agronomia, Universidade de LisboaLisboa, Portugal
| | - Luis Gil
- Forest Genetics and Ecophysiology Research Group, Plant Physiology and Anatomy Unit, School of Forest Engineering, Technical University of MadridMadrid, Spain
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