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Triplett G, Buckley TN, Muir CD. Amphistomy increases leaf photosynthesis more in coastal than montane plants of Hawaiian 'ilima (Sida fallax). AMERICAN JOURNAL OF BOTANY 2024; 111:e16284. [PMID: 38351495 DOI: 10.1002/ajb2.16284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 12/19/2023] [Accepted: 12/19/2023] [Indexed: 02/22/2024]
Abstract
PREMISE The adaptive significance of amphistomy (stomata on both upper and lower leaf surfaces) is unresolved. A widespread association between amphistomy and open, sunny habitats suggests the adaptive benefit of amphistomy may be greatest in these contexts, but this hypothesis has not been tested experimentally. Understanding amphistomy informs its potential as a target for crop improvement and paleoenvironment reconstruction. METHODS We developed a method to quantify "amphistomy advantage" (AA $\text{AA}$ ) as the log-ratio of photosynthesis in an amphistomatous leaf to that of the same leaf but with gas exchange blocked through the upper surface (pseudohypostomy). Humidity modulated stomatal conductance and thus enabled comparing photosynthesis at the same total stomatal conductance. We estimatedAA $\text{AA}$ and leaf traits in six coastal (open, sunny) and six montane (closed, shaded) populations of the indigenous Hawaiian species 'ilima (Sida fallax). RESULTS Coastal 'ilima leaves benefit 4.04 times more from amphistomy than montane leaves. Evidence was equivocal with respect to two hypotheses: (1) that coastal leaves benefit more because they are thicker and have lower CO2 conductance through the internal airspace and (2) that they benefit more because they have similar conductance on each surface, as opposed to most conductance being through the lower surface. CONCLUSIONS This is the first direct experimental evidence that amphistomy increases photosynthesis, consistent with the hypothesis that parallel pathways through upper and lower mesophyll increase CO2 supply to chloroplasts. The prevalence of amphistomatous leaves in open, sunny habitats can partially be explained by the increased benefit of amphistomy in "sun" leaves, but the mechanistic basis remains uncertain.
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Affiliation(s)
- Genevieve Triplett
- School of Life Sciences, University of Hawai'i Mānoa, Honolulu, HI, 96822, USA
| | - Thomas N Buckley
- Department of Plant Sciences, University of California, Davis, CA, 95616, USA
| | - Christopher D Muir
- School of Life Sciences, University of Hawai'i Mānoa, Honolulu, HI, 96822, USA
- Department of Botany, University of Wisconsin, Madison, WI, 53706, USA
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Driesen E, De Proft M, Saeys W. Drought stress triggers alterations of adaxial and abaxial stomatal development in basil leaves increasing water-use efficiency. HORTICULTURE RESEARCH 2023; 10:uhad075. [PMID: 37303614 PMCID: PMC10251137 DOI: 10.1093/hr/uhad075] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 04/10/2023] [Indexed: 06/13/2023]
Abstract
The physiological control of stomatal opening by which plants adjust for water availability has been extensively researched. However, the impact of water availability on stomatal development has not received as much attention, especially for amphistomatic plants. Therefore, the acclimation of stomatal development in basil (Ocimum basilicum L.) leaves was investigated. Our results show that leaves developed under water-deficit conditions possess higher stomatal densities and decreased stomatal length for both the adaxial and abaxial leaf sides. Although the stomatal developmental reaction to water deficit was similar for the two leaf surfaces, it was proven that adaxial stomata are more sensitive to water stress than abaxial stomata, with more closed adaxial stomata under water-deficit conditions. Furthermore, plants with leaves containing smaller stomata at higher densities possessed a higher water use efficiency. Our findings highlight the importance of stomatal development as a tool for long-term acclimation to limit water loss, with minimal reduction in biomass production. This highlights the central role that stomata play in both the short (opening) and long-term (development) reaction of plants to water availability, making them key tools for efficient resource use and anticipation of future environmental changes.
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Affiliation(s)
| | - Maurice De Proft
- Department of Biosystems, KU Leuven, Willem De Croylaan 42, 3001 Leuven, Belgium
| | - Wouter Saeys
- Department of Biosystems, KU Leuven, Willem De Croylaan 42, 3001 Leuven, Belgium
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Abstract
When microscopy meets modelling the exciting concept of a 'virtual leaf' is born. The goal of a 'virtual leaf' is to capture complex physiology in a virtual environment, resulting in the capacity to run experiments computationally. One example of a 'virtual leaf' application is capturing 3D anatomy from volume microscopy data and estimating where water evaporates in the leaf and the proportions of apoplastic, symplastic and gas phase water transport. The same 3D anatomy could then be used to improve established 3D reaction-diffusion models, providing a better understanding of the transport of CO2 across the stomata, through the airspace and across the mesophyll cell wall. This viewpoint discusses recent progress that has been made in transitioning from a bulk leaf approach to a 3D understanding of leaf physiology, in particular, the movement of CO2 and H2O within the leaf.
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Wang T, Zheng L, Xiong D, Wang F, Man J, Deng N, Cui K, Huang J, Peng S, Ling X. Stomatal Ratio Showing No Response to Light Intensity in Oryza. PLANTS (BASEL, SWITZERLAND) 2022; 12:66. [PMID: 36616195 PMCID: PMC9823486 DOI: 10.3390/plants12010066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 12/09/2022] [Accepted: 12/20/2022] [Indexed: 06/17/2023]
Abstract
Stomata control carbon and water exchange between the leaves and the ambient. However, the plasticity responses of stomatal traits to growth conditions are still unclear, especially for monocot leaves. The current study investigated the leaf anatomical traits, stomatal morphological traits on both adaxial and abaxial leaf surfaces, and photosynthetic traits of Oryza leaves developed in two different growth conditions. Substantial variation exists across the Oryza species in leaf anatomy, stomatal traits, photosynthetic rate, and stomatal conductance. The abaxial stomatal density was higher than the adaxial stomatal density in all the species, and the stomatal ratios ranged from 0.35 to 0.46 across species in two growth environments. However, no difference in the stomatal ratio was observed between plants in the growth chamber and outdoors for a given species. Photosynthetic capacity, stomatal conductance, leaf width, major vein thickness, minor vein thickness, inter-vein distance, and stomatal pore width values for leaves grown outdoors were higher than those for plants grown in the growth chamber. Our results indicate that a broad set of leaf anatomical, stomatal, and photosynthetic traits of Oryza tend to shift together during plasticity to diverse growing conditions, but the previously projected sensitive trait, stomatal ratio, does not shape growth conditions.
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Borsuk AM, Roddy AB, Théroux‐Rancourt G, Brodersen CR. Structural organization of the spongy mesophyll. THE NEW PHYTOLOGIST 2022; 234:946-960. [PMID: 35037256 PMCID: PMC9303971 DOI: 10.1111/nph.17971] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 12/21/2021] [Indexed: 05/21/2023]
Abstract
Many plant leaves have two layers of photosynthetic tissue: the palisade and spongy mesophyll. Whereas palisade mesophyll consists of tightly packed columnar cells, the structure of spongy mesophyll is not well characterized and often treated as a random assemblage of irregularly shaped cells. Using micro-computed tomography imaging, topological analysis, and a comparative physiological framework, we examined the structure of the spongy mesophyll in 40 species from 30 genera with laminar leaves and reticulate venation. A spectrum of spongy mesophyll diversity encompassed two dominant phenotypes: first, an ordered, honeycomblike tissue structure that emerged from the spatial coordination of multilobed cells, conforming to the physical principles of Euler's law; and second, a less-ordered, isotropic network of cells. Phenotypic variation was associated with transitions in cell size, cell packing density, mesophyll surface-area-to-volume ratio, vein density, and maximum photosynthetic rate. These results show that simple principles may govern the organization and scaling of the spongy mesophyll in many plants and demonstrate the presence of structural patterns associated with leaf function. This improved understanding of mesophyll anatomy provides new opportunities for spatially explicit analyses of leaf development, physiology, and biomechanics.
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Affiliation(s)
| | - Adam B. Roddy
- Department of Biological SciencesInstitute of EnvironmentFlorida International UniversityMiamiFL33199USA
| | - Guillaume Théroux‐Rancourt
- Department of Integrative Biology and Biodiversity ResearchInstitute of BotanyUniversity of Natural Resources and Life Sciences, Vienna1180ViennaAustria
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Nelson TC, Muir CD, Stathos AM, Vanderpool DD, Anderson K, Angert AL, Fishman L. Quantitative trait locus mapping reveals an independent genetic basis for joint divergence in leaf function, life-history, and floral traits between scarlet monkeyflower (Mimulus cardinalis) populations. AMERICAN JOURNAL OF BOTANY 2021; 108:844-856. [PMID: 34036561 DOI: 10.1002/ajb2.1660] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Accepted: 01/12/2021] [Indexed: 06/12/2023]
Abstract
PREMISE Across taxa, vegetative and floral traits that vary along a fast-slow life-history axis are often correlated with leaf functional traits arrayed along the leaf economics spectrum, suggesting a constrained set of adaptive trait combinations. Such broad-scale convergence may arise from genetic constraints imposed by pleiotropy (or tight linkage) within species, or from natural selection alone. Understanding the genetic basis of trait syndromes and their components is key to distinguishing these alternatives and predicting evolution in novel environments. METHODS We used a line-cross approach and quantitative trait locus (QTL) mapping to characterize the genetic basis of twenty leaf functional/physiological, life history, and floral traits in hybrids between annualized and perennial populations of scarlet monkeyflower (Mimulus cardinalis). RESULTS We mapped both single and multi-trait QTLs for life history, leaf function and reproductive traits, but found no evidence of genetic co-ordination across categories. A major QTL for three leaf functional traits (thickness, photosynthetic rate, and stomatal resistance) suggests that a simple shift in leaf anatomy may be key to adaptation to seasonally dry habitats. CONCLUSIONS Our results suggest that the co-ordination of resource-acquisitive leaf physiological traits with a fast life-history and more selfing mating system results from environmental selection rather than functional or genetic constraint. Independent assortment of distinct trait modules, as well as a simple genetic basis to leaf physiological traits associated with drought escape, may facilitate adaptation to changing climates.
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Affiliation(s)
- Thomas C Nelson
- Division of Biological Sciences, University of Montana, Missoula, Montana, 59812, USA
| | - Christopher D Muir
- Departments of Botany and Zoology and Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada
- School of Life Sciences, University of Hawai'i, Honolulu, Hawai'i, 96822, USA
| | - Angela M Stathos
- Division of Biological Sciences, University of Montana, Missoula, Montana, 59812, USA
| | - Daniel D Vanderpool
- Division of Biological Sciences, University of Montana, Missoula, Montana, 59812, USA
| | - Kayli Anderson
- Division of Biological Sciences, University of Montana, Missoula, Montana, 59812, USA
| | - Amy L Angert
- Departments of Botany and Zoology and Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada
| | - Lila Fishman
- Division of Biological Sciences, University of Montana, Missoula, Montana, 59812, USA
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Xiong D, Flexas J. From one side to two sides: the effects of stomatal distribution on photosynthesis. THE NEW PHYTOLOGIST 2020; 228:1754-1766. [PMID: 32652573 DOI: 10.1111/nph.16801] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 07/02/2020] [Indexed: 06/11/2023]
Abstract
The functions of stomata have been studied for a long time; however, a clear understanding of the influences of stomatal distribution on photosynthesis, especially the CO2 diffusion, is still unclear. Here, we investigated the stomatal morphology, distribution on leaf surfaces, vein traits and gas exchange parameters of 61 species, of which 29 were amphistomatous, spanning 32 families. Photosynthesis (A) was tightly coupled with operational stomatal conductance (gs ) and mesophyll conductance (gm ) regardless of whether phylogenetic relationships were accounted for. Although the enhancement of gs from ferns and gymnosperms to angiosperms could largely be explained by the increase in leaf vein density (VLA) and stomatal density (SD), the gs was decoupled from VLA and SD across angiosperm species. Instead, A in angiosperms was further influenced by the allocation of stomatal pores on leaf surfaces, which dramatically increased gs and gm . Moreover, the ratio of gs to anatomically based maximum gs was, on average, 0.12 across species. Our results show that the shift of stomatal pores from one leaf side to both sides played an important role in regulating CO2 diffusion via both stomata and mesophyll tissues. Modifications of stomata distribution have potential as a functional trait for photosynthesis improvement.
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Affiliation(s)
- Dongliang Xiong
- National Key Laboratory of Crop Genetic Improvement, MOA Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Jaume Flexas
- Research Group on Plant Biology under Mediterranean Conditions, Universitat de les Illes Balears/Instituto de Investigaciones Agroambientales y de Economía del Agua (INAGEA), Carretera de Valldemossa Km 7.5, Palma de Mallorca, Illes Balears, 07121, Spain
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Pathare VS, Sonawane BV, Koteyeva N, Cousins AB. C 4 grasses adapted to low precipitation habitats show traits related to greater mesophyll conductance and lower leaf hydraulic conductance. PLANT, CELL & ENVIRONMENT 2020; 43:1897-1910. [PMID: 32449181 DOI: 10.1111/pce.13807] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 05/18/2020] [Indexed: 06/11/2023]
Abstract
In habitats with low water availability, a fundamental challenge for plants will be to maximize photosynthetic C-gain while minimizing transpirational water-loss. This trade-off between C-gain and water-loss can in part be achieved through the coordination of leaf-level photosynthetic and hydraulic traits. To test the relationship of photosynthetic C-gain and transpirational water-loss, we grew, under common growth conditions, 18 C4 grasses adapted to habitats with different mean annual precipitation (MAP) and measured leaf-level structural and anatomical traits associated with mesophyll conductance (gm ) and leaf hydraulic conductance (Kleaf ). The C4 grasses adapted to lower MAP showed greater mesophyll surface area exposed to intercellular air spaces (Smes ) and adaxial stomatal density (SDada ) which supported greater gm . These grasses also showed greater leaf thickness and vein-to-epidermis distance, which may lead to lower Kleaf . Additionally, grasses with greater gm and lower Kleaf also showed greater photosynthetic rates (Anet ) and leaf-level water-use efficiency (WUE). In summary, we identify a suite of leaf-level traits that appear important for adaptation of C4 grasses to habitats with low MAP and may be useful to identify C4 species showing greater Anet and WUE in drier conditions.
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Affiliation(s)
- Varsha S Pathare
- School of Biological Sciences, Washington State University, Pullman, Washington, USA
| | - Balasaheb V Sonawane
- School of Biological Sciences, Washington State University, Pullman, Washington, USA
| | - Nouria Koteyeva
- School of Biological Sciences, Washington State University, Pullman, Washington, USA
- Laboratory of Anatomy and Morphology, V.L. Komarov Botanical Institute of the Russian Academy of Sciences, St. Petersburg, Russia
| | - Asaph B Cousins
- School of Biological Sciences, Washington State University, Pullman, Washington, USA
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Matthew Ogburn R, Edwards EJ. Celebrating a New Division of Botany at SICB: An Introduction to the Integrative Plant Biology Symposium. Integr Comp Biol 2020; 59:489-492. [PMID: 31411674 DOI: 10.1093/icb/icz114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The Society for Integrative and Comparative Biology (SICB) should, in theory, be a home for scientists working across the entire Tree of Life. In practice, SICB has remained principally a society that supports integrative zoological research. Here we highlight a broad collection of what we consider to the best in integrative and comparative plant biology, gathered together for a special symposium at the 2019 SICB meeting. This symposium and special issue mark the initiation of a new Division of Botany within SICB, which we hope will usher in a new era of SICB where botanists and zoologists engage, collaborate, and celebrate together in this especially creative period of integrative and comparative biology.
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Affiliation(s)
- R Matthew Ogburn
- Department of Biology, Southern Utah University, 351 West University Blvd, Cedar City, UT 84720, USA
| | - Erika J Edwards
- Department of Ecology and Evolutionary Biology, Yale University, 165 Prospect Street, New Haven, CT 06511, USA
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Muir CD. tealeaves: an R package for modelling leaf temperature using energy budgets. AOB PLANTS 2019; 11:plz054. [PMID: 31844509 PMCID: PMC6899345 DOI: 10.1093/aobpla/plz054] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 09/21/2019] [Indexed: 05/29/2023]
Abstract
Plants must regulate leaf temperature to optimize photosynthesis, control water loss and prevent damage caused by overheating or freezing. Physical models of leaf energy budgets calculate the energy fluxes and leaf temperatures for a given set leaf and environmental parameters. These models can provide deep insight into the variation in leaf form and function, but there are few computational tools available to use these models. Here I introduce a new R package called tealeaves to make complex leaf energy budget models accessible to a broader array of plant scientists. This package enables novice users to start modelling leaf energy budgets quickly while allowing experts to customize their parameter settings. The code is open source, freely available and readily integrates with other R tools for scientific computing. This paper describes the current functionality of tealeaves, but new features will be added in future releases. This software tool will advance new research on leaf thermal physiology to advance our understanding of basic and applied plant science.
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