1
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Liu J, Carriquí M, Xiong D, Kang S. Influence of IAA and ABA on maize stem vessel diameter and stress resistance in variable environments. PHYSIOLOGIA PLANTARUM 2024; 176:e14443. [PMID: 39039017 DOI: 10.1111/ppl.14443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Revised: 06/25/2024] [Accepted: 07/09/2024] [Indexed: 07/24/2024]
Abstract
The plasticity of the xylem and its associated hydraulic properties play crucial roles in plant acclimation to environmental changes, with vessel diameter (Dv) being the most functionally prominent trait. While the effects of external environmental factors on xylem formation and Dv are not fully understood, the endogenous hormones indole-3-acetic acid (IAA) and abscisic acid (ABA) are known to play significant signalling roles under stress conditions. This study investigates how these hormones impact Dv under various environmental changes. Experiments were conducted in maize plants subjected to drought, soil salinity, and high CO2 concentration treatments. We found that drought and soil salinity significantly reduced Dv at the same stem internode, while an elevated CO2 concentration can mitigate this decrease in Dv. Remarkably, significant negative correlations were observed between Dv and the contents of IAA and ABA when considering the different treatments. Moreover, appropriate foliar application of either IAA or ABA on well-watered and stressed plants led to a decrease in Dv, while the application of corresponding inhibitors resulted in an increase in Dv. This finding underscores the causal relationship between Dv and the levels of both IAA and ABA, offering a promising approach to manipulating xylem vessel size.
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Affiliation(s)
- Junzhou Liu
- Center for Agricultural Water Research in China, China Agricultural University, Beijing, China
- National Field Scientific Observation and Research Station on Efficient Water Use of Oasis Agriculture in Wuwei of Gansu Province, Wuwei, China
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Marc Carriquí
- Research Group in Plant Biology under Mediterranean Conditions, Universitat de les Illes Balears, Palma, Spain
| | - Dongliang Xiong
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Shaozhong Kang
- Center for Agricultural Water Research in China, China Agricultural University, Beijing, China
- National Field Scientific Observation and Research Station on Efficient Water Use of Oasis Agriculture in Wuwei of Gansu Province, Wuwei, China
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2
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Grossman JJ, Coe HB, Fey O, Fraser N, Salaam M, Semper C, Williamson CG. Temperate woody species across the angiosperm phylogeny acquire tolerance to water deficit stress during the growing season. THE NEW PHYTOLOGIST 2024. [PMID: 38511237 DOI: 10.1111/nph.19692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Accepted: 03/03/2024] [Indexed: 03/22/2024]
Abstract
Understanding the capacity of temperate trees to acclimate to limited soil water has become essential in the face of increasing drought risk due to climate change. We documented seasonal - or phenological - patterns in acclimation to water deficit stress in stems and leaves of tree species spanning the angiosperm phylogeny. Over 3 yr of field observations carried out in two US arboreta, we measured stem vulnerability to embolism (36 individuals of 7 Species) and turgor loss point (119 individuals of 27 species) over the growing season. We also conducted a growth chamber experiment on 20 individuals of one species to assess the mechanistic relationship between soil water restriction and acclimation. In three-quarters of species measured, plants became less vulnerable to embolism and/or loss of turgor over the growing season. We were able to stimulate this acclimatory effect by withholding water in the growth chamber experiment. Temperate angiosperms are capable of acclimation to soil water deficit stress, showing maximum vulnerability to soil water deficits following budbreak and becoming more resilient to damage over the course of the growing season or in response to simulated drought. The species-specific tempo and extent of this acclimatory potential constitutes preadaptive climate change resilience.
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Affiliation(s)
- Jake J Grossman
- Biology Department & Environmental Studies Department, St. Olaf College, 1520 St Olaf Ave, Northfield, MN, 55057, USA
| | - Henry B Coe
- Environmental Permitting and Planning Group, Hazen and Sawyer 498 Seventh Ave #11, New York, NY, 10018, USA
| | - Olivia Fey
- Biology Department, Swarthmore College, 500 College Ave, Swarthmore, PA, 19081, USA
| | - Natalie Fraser
- Biology Department, Swarthmore College, 500 College Ave, Swarthmore, PA, 19081, USA
| | - Musa Salaam
- Wilmer Eye Institute, Bayview Medical Center, Johns Hopkins University, 4940 Eastern Ave, Baltimore, MD, 21224, USA
| | - Chelsea Semper
- Department of Forest Resources, University of Minnesota, 115 Green Hall, 1530 Cleveland Ave N, St. Paul, MN, 55108, USA
| | - Ceci G Williamson
- Biology Department, Swarthmore College, 500 College Ave, Swarthmore, PA, 19081, USA
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3
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Chu C, Momayyezi M, Stobbs JA, Soolanayakanahally RY, McElrone AJ, Knipfer T. Drought-induced fiber water release and xylem embolism susceptibility of intact balsam poplar saplings. PHYSIOLOGIA PLANTARUM 2023; 175:e14040. [PMID: 37882281 DOI: 10.1111/ppl.14040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 08/31/2023] [Accepted: 09/27/2023] [Indexed: 10/27/2023]
Abstract
Balsam poplar (Populus balsamifera L.) is a widespread tree species in North America with significant ecological and economic value. However, little is known about the susceptibility of saplings to drought-induced embolism and its link to water release from surrounding xylem fibers. Questions remain regarding localized mechanisms that contribute to the survival of saplings in vivo of this species under drought. Using X-ray micro-computed tomography on intact saplings of genotypes Gillam-5 and Carnduff-9, we found that functional vessels are embedded in a matrix of water-filled fibers under well-watered conditions in both genotypes. However, water-depleted fibers started to appear under moderate drought stress while vessels remained water-filled in both genotypes. Drought-induced xylem embolism susceptibility was comparable between genotypes, and a greater frequency of smaller diameter vessels in GIL-5 did not increase embolism resistance in this genotype. Despite having smaller vessels and a total vessel number that was comparable to CAR-9, stomatal conductance was generally higher in GIL-5 compared to CAR-9. In conclusion, our in vivo data on intact saplings indicate that differences in embolism susceptibility are negligible between GIL-5 and CAR-9, and that fiber water release should be considered as a mechanism that contributes to the maintenance of vessel functional status in saplings of balsam poplar experiencing their first drought event.
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Affiliation(s)
- Cheyenne Chu
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, British Columbia, Canada
| | - Mina Momayyezi
- Department of Viticulture and Enology, University of California, Davis, California, USA
| | | | | | - Andrew J McElrone
- Department of Viticulture and Enology, University of California, Davis, California, USA
- USDA-ARS, Crops Pathology and Genetics Research Unit, Davis, California, USA
| | - Thorsten Knipfer
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, British Columbia, Canada
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4
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Feng F, Wagner Y, Klein T, Hochberg U. Xylem resistance to cavitation increases during summer in Pinus halepensis. PLANT, CELL & ENVIRONMENT 2023; 46:1849-1859. [PMID: 36793149 DOI: 10.1111/pce.14573] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Revised: 02/08/2023] [Accepted: 02/14/2023] [Indexed: 05/04/2023]
Abstract
Cavitation resistance has often been viewed as a relatively static trait, especially for stems of forest trees. Meanwhile, other hydraulic traits, such as turgor loss point (Ψtlp ) and xylem anatomy, change during the season. In this study, we hypothesized that cavitation resistance is also dynamic, changing in coordination with Ψtlp . We began with a comparison of optical vulnerability (OV), microcomputed tomography (µCT) and cavitron methods. All three methods significantly differed in the slope of the curve,Ψ12 and Ψ88 , but not in Ψ50 (xylem pressures that cause 12%, 88%, 50% cavitation, respectively). Thus, we followed the seasonal dynamics (across 2 years) of Ψ50 in Pinus halepensis under Mediterranean climate using the OV method. We found that Ψ50 is a plastic trait with a reduction of approximately 1 MPa from the end of the wet season to the end of the dry season, in coordination with the dynamics of the midday xylem water potential (Ψmidday ) and the Ψtlp . The observed plasticity enabled the trees to maintain a stable positive hydraulic safety margin and avoid cavitation during the long dry season. Seasonal plasticity is vital for understanding the actual risk of cavitation to plants and for modeling species' ability to tolerate harsh environments.
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Affiliation(s)
- Feng Feng
- Institute of Soil, Water and Environmental Sciences, Volcani Center, Agricultural Research Organization, Rishon LeZion, Israel
- Department of Botany, University of Innsbruck, Innsbruck, Austria
| | - Yael Wagner
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Tamir Klein
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Uri Hochberg
- Institute of Soil, Water and Environmental Sciences, Volcani Center, Agricultural Research Organization, Rishon LeZion, Israel
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5
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Grossman JJ. Phenological physiology: seasonal patterns of plant stress tolerance in a changing climate. THE NEW PHYTOLOGIST 2023; 237:1508-1524. [PMID: 36372992 DOI: 10.1111/nph.18617] [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: 05/31/2022] [Accepted: 09/29/2022] [Indexed: 06/16/2023]
Abstract
The physiological challenges posed by climate change for seasonal, perennial plants include increased risk of heat waves, postbudbreak freezing ('false springs'), and droughts. Although considerable physiological work has shown that the traits conferring tolerance to these stressors - thermotolerance, cold hardiness, and water deficit stress, respectively - are not static in time, they are frequently treated as such. In this review, I synthesize the recent literature on predictable seasonal - and therefore, phenological - patterns of acclimation and deacclimation to heat, cold, and water-deficit stress in perennials, focusing on woody plants native to temperate climates. I highlight promising, high-throughput techniques for quantifying thermotolerance, cold hardiness, and drought tolerance. For each of these forms of stress tolerance, I summarize the current balance of evidence regarding temporal patterns over the course of a year and suggest a characteristic temporal scale in these responses to environmental stress. In doing so, I offer a synthetic framework of 'phenological physiology', in which understanding and leveraging seasonally recurring (phenological) patterns of physiological stress acclimation can facilitate climate change adaptation and mitigation.
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Affiliation(s)
- Jake J Grossman
- Department of Biology, St. Olaf College, 1520 St Olaf Ave., St Olaf, MN, 55057, USA
- Department of Environmental Studies, St Olaf College, 1520 St Olaf Ave., St Olaf, MN, 55057, USA
- Arnold Arboretum of Harvard University, 1300 Centre St., Boston, MA, 02131, USA
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6
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Augstein F, Carlsbecker A. Salinity induces discontinuous protoxylem via a DELLA-dependent mechanism promoting salt tolerance in Arabidopsis seedlings. THE NEW PHYTOLOGIST 2022; 236:195-209. [PMID: 35746821 PMCID: PMC9545557 DOI: 10.1111/nph.18339] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Accepted: 06/11/2022] [Indexed: 06/15/2023]
Abstract
Salinity is detrimental to plants and developmental adjustments limiting salt uptake and transport is therefore important for acclimation to high salt. These parameters may be influenced by xylem morphology, however how plant root xylem development is affected by salt stress remains unclear. Using molecular and genetic techniques and detailed phenotypic analyses, we demonstrate that salt causes distinct effects on Arabidopsis seedling root xylem and reveal underlying molecular mechanisms. Salinity causes intermittent inhibition of protoxylem cell differentiation, generating protoxylem gaps, in Arabidopsis and several other eudicot seedlings. The extent of protoxylem gaps in seedlings positively correlates with salt tolerance. Reduced gibberellin signalling is required for protoxylem gap formation. Mutant analyses reveal that the xylem differentiation regulator VASCULAR RELATED NAC DOMAIN 6 (VND6), along with secondary cell wall producing and cell wall modifying enzymes, including EXPANSIN A1 (EXP1), are involved in protoxylem gap formation, in a DELLA-dependent manner. Salt stress is likely to reduce levels of bioactive gibberellins, stabilising DELLAs, which in turn activates multiple factors modifying protoxylem differentiation. Salt stress impacts seedling survival and formation of protoxylem gaps may be a measure to enhance salt tolerance.
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Affiliation(s)
- Frauke Augstein
- Department of Organismal Biology, Physiological Botany, and Linnean Centre for Plant BiologyUppsala UniversityUllsv. 24ESE‐756 51UppsalaSweden
| | - Annelie Carlsbecker
- Department of Organismal Biology, Physiological Botany, and Linnean Centre for Plant BiologyUppsala UniversityUllsv. 24ESE‐756 51UppsalaSweden
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7
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Cardoso AA, Kane CN, Rimer IM, McAdam SAM. Seeing is believing: what visualising bubbles in the xylem has revealed about plant hydraulic function. FUNCTIONAL PLANT BIOLOGY : FPB 2022; 49:759-772. [PMID: 35718950 DOI: 10.1071/fp21326] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 05/29/2022] [Indexed: 06/15/2023]
Abstract
Maintaining water transport in the xylem is critical for vascular plants to grow and survive. The drought-induced accumulation of embolism, when gas enters xylem conduits, causes declines in hydraulic conductance (K ) and is ultimately lethal. Several methods can be used to estimate the degree of embolism in xylem, from measuring K in tissues to directly visualising embolism in conduits. One method allowing a direct quantification of embolised xylem area is the optical vulnerability (OV) technique. This method has been used across different organs and has a high spatial and temporal resolution. Here, we review studies using the OV technique, discuss the main advantages and disadvantages of this method, and summarise key advances arising from its use. Vulnerability curves generated by the OV method are regularly comparable to other methods, including the centrifuge and X-ray microtomography. A major advantage of the OV technique over other methods is that it can be simultaneously used to determine in situ embolism formation in leaves, stems and roots, in species spanning the phylogeny of land plants. The OV method has been used to experimentally investigate the spreading of embolism through xylem networks, associate embolism with downstream tissue death, and observe embolism formation in the field.
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Affiliation(s)
- Amanda A Cardoso
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, NC 27695, USA
| | - Cade N Kane
- Purdue Center for Plant Biology, Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, USA
| | - Ian M Rimer
- Purdue Center for Plant Biology, Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, USA
| | - Scott A M McAdam
- Purdue Center for Plant Biology, Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, USA
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8
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Wagner Y, Feng F, Yakir D, Klein T, Hochberg U. In situ, direct observation of seasonal embolism dynamics in Aleppo pine trees growing on the dry edge of their distribution. THE NEW PHYTOLOGIST 2022; 235:1344-1350. [PMID: 35514143 PMCID: PMC9541785 DOI: 10.1111/nph.18208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 04/30/2022] [Indexed: 06/14/2023]
Abstract
Xylem embolism impairs hydraulic conductivity in trees and drives drought-induced mortality. While embolism has been monitored in vivo in potted plants, and research has revealed evidence of embolism in field-grown trees, continuous in situ monitoring of cavitation in forests is lacking. Seasonal patterns of embolism were monitored in branchlets of Aleppo pine (Pinus halepensis) trees growing in a dry Mediterranean forest. Optical visualization (OV) sensors were installed on terminal branches, in addition to monthly sampling for micro computed tomography scans. We detected 208 cavitation events among four trees, which represented an embolism increase from zero to c. 12% along the dry season. Virtually all the cavitation events occurred during daytime hours, with 77% occurring between 10:00 and 17:00 h. The probability for cavitation in a given hour increased as vapor pressure deficit (VPD) increased, up to a probability of 42% for cavitation when VPD > 5 kPa. The findings uniquely reveal the instantaneous environmental conditions that lead to cavitation. The increased likelihood of cavitation events under high VPD in water-stressed pines is the first empirical support for this long hypothesized relationship. Our observations suggest that low levels of embolism are common in Aleppo pine trees at the dry edge of their distribution.
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Affiliation(s)
- Yael Wagner
- Plant & Environmental Sciences DepartmentWeizmann Institute of ScienceRehovot7610001Israel
| | - Feng Feng
- Institute of Soil, Water and Environmental SciencesVolcani CenterARORishon Lezion7505101Israel
| | - Dan Yakir
- Earth and Planetary Science DepartmentWeizmann Institute of ScienceRehovot7610001Israel
| | - Tamir Klein
- Plant & Environmental Sciences DepartmentWeizmann Institute of ScienceRehovot7610001Israel
| | - Uri Hochberg
- Institute of Soil, Water and Environmental SciencesVolcani CenterARORishon Lezion7505101Israel
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9
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Limousin JM, Roussel A, Rodríguez-Calcerrada J, Torres-Ruiz JM, Moreno M, Garcia de Jalon L, Ourcival JM, Simioni G, Cochard H, Martin-StPaul N. Drought acclimation of Quercus ilex leaves improves tolerance to moderate drought but not resistance to severe water stress. PLANT, CELL & ENVIRONMENT 2022; 45:1967-1984. [PMID: 35394675 DOI: 10.1111/pce.14326] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 03/12/2022] [Accepted: 03/22/2022] [Indexed: 06/14/2023]
Abstract
Increasing temperature and drought can result in leaf dehydration and defoliation even in drought-adapted tree species such as the Mediterranean evergreen Quercus ilex L. The stomatal regulation of leaf water potential plays a central role in avoiding this phenomenon and is constrained by a suite of leaf traits including hydraulic conductance and vulnerability, hydraulic capacitance, minimum conductance to water vapour, osmotic potential and cell wall elasticity. We investigated whether the plasticity in these traits may improve leaf tolerance to drought in two long-term rainfall exclusion experiments in Mediterranean forests. Osmotic adjustment was observed to lower the water potential at turgor loss in the rainfall-exclusion treatments, thus suggesting a stomatal closure at more negative water potentials and a more anisohydric behaviour in drier conditions. Conversely, leaf hydraulic conductance and vulnerability did not exhibit any plasticity between treatments so the hydraulic safety margins were narrower in the rainfall-exclusion treatments. The sequence of leaf responses to seasonal drought and dehydration was conserved among treatments and sites but trees were more likely to suffer losses of turgor and hydraulic functioning in the rainfall-exclusion treatments. We conclude that leaf plasticity might help the trees to tolerate moderate drought but not to resist severe water stress.
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Affiliation(s)
| | - Amélie Roussel
- CEFE, Univ Montpellier, CNRS, EPHE, IRD, Montpellier, France
| | - Jesús Rodríguez-Calcerrada
- Departamento de Sistemas y Recursos Naturales, ETSI Montes, Forestal y del Medio Natural, Universidad Politécnica de Madrid Ciudad Universitaria, Madrid, Spain
| | | | - Myriam Moreno
- Unité Ecologie des Forêts Méditerranéennes (UR629), INRAE Avignon Cedex 9, Domaine Saint Paul, Site Agroparc, France
| | | | | | - Guillaume Simioni
- Unité Ecologie des Forêts Méditerranéennes (UR629), INRAE Avignon Cedex 9, Domaine Saint Paul, Site Agroparc, France
| | - Hervé Cochard
- PIAF, University Clermont-Auvergne, INRAE, Clermont-Ferrand, France
| | - Nicolas Martin-StPaul
- Unité Ecologie des Forêts Méditerranéennes (UR629), INRAE Avignon Cedex 9, Domaine Saint Paul, Site Agroparc, France
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10
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Influence of Juvenile Growth on Xylem Safety and Efficiency in Three Temperate Tree Species. FORESTS 2022. [DOI: 10.3390/f13060909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The evolution of the internal water transport system was a prerequisite for high plant productivity. In times of climate change, understanding the dependency of juvenile growth on xylem hydraulic physiology is therefore of high importance. Here, we explored various wood anatomical, hydraulic, and leaf morphological traits related to hydraulic safety and efficiency in three temperate broadleaved tree species (Acer pseudoplatanus, Betula pendula, and Sorbus aucuparia). We took advantage of a severe natural heat wave that resulted in different climatic growing conditions for even-aged plants from the same seed source growing inside a greenhouse and outside. Inside the greenhouse, the daily maximum vapour pressure deficit was on average 36% higher than outside during the growing seasons. Because of the higher atmospheric moisture stress, the biomass production differed up to 5.6-fold between both groups. Except for one species, a high productivity was associated with a high hydraulic efficiency caused by large xylem vessels and a large, supported leaf area. Although no safety-efficiency trade-off was observed, productivity was significantly related to P50 in two of the tree species but without revealing any clear pattern. A considerable plasticity in given traits was observed between both groups, with safety-related traits being more static while efficiency-related traits revealed a higher intra-specific plasticity. This was associated with other wood anatomical and leaf morphological adjustments. We confirm that a high hydraulic efficiency seems to be a prerequisite for a high biomass production, while our controversial results on the growth–xylem safety relationship confirm that safety-efficiency traits are decoupled and that their relationship with juvenile growth and water regime is species-specific.
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11
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Hietz P, Rungwattana K, Scheffknecht S, George JP. Effects of Provenance, Growing Site, and Growth on Quercus robur Wood Anatomy and Density in a 12-Year-Old Provenance Trial. FRONTIERS IN PLANT SCIENCE 2022; 13:795941. [PMID: 35574121 PMCID: PMC9100569 DOI: 10.3389/fpls.2022.795941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 03/22/2022] [Indexed: 06/15/2023]
Abstract
Vessels are responsible for an efficient and safe water transport in angiosperm xylem. Whereas large vessels efficiently conduct the bulk of water, small vessels might be important under drought stress or after winter when large vessels are embolized. Wood anatomy can adjust to the environment by plastic adaptation, but is also modified by genetic selection, which can be driven by climate or other factors. To distinguish between plastic and genetic components on wood anatomy, we used a Quercus robur trial where trees from ten Central European provenances were planted in three locations in Austria along a rainfall gradient. Because wood anatomy also adjusts to tree size and in ring-porous species, the vessel size depends on the amount of latewood and thereby ring width, we included tree size and ring width in the analysis. We found that the trees' provenance had a significant effect on average vessel area (VA), theoretical specific hydraulic conductivity (Ks), and the vessel fraction (VF), but correlations with annual rainfall of provenances were at best weak. The trial site had a strong effect on growth (ring width, RW), which increased from the driest to the wettest site and wood density (WD), which increased from wet to dry sites. Significant site x provenance interactions were seen only for WD. Surprisingly, the drier site had higher VA, higher VF, and higher Ks. This, however, is mainly a result of greater RW and thus a greater proportion of latewood in the wetter forest. The average size of vessels > 70 μm diameter increased with rainfall. We argue that Ks, which is measured per cross-sectional area, is not an ideal parameter to compare the capacity of ring-porous trees to supply leaves with water. Small vessels (<70 μm) on average contributed only 1.4% to Ks, and we found no evidence that their number or size was adaptive to aridity. RW and tree size had strong effect on all vessel parameters, likely via the greater proportion of latewood in wide rings. This should be accounted for when searching for wood anatomical adaptations to the environment.
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Affiliation(s)
- Peter Hietz
- Department of Integrative Biology and Biodiversity Research, Institute of Botany, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Kanin Rungwattana
- Department of Integrative Biology and Biodiversity Research, Institute of Botany, University of Natural Resources and Life Sciences, Vienna, Austria
- Department of Botany, Faculty of Science, Kasetsart University, Bangkok, Thailand
| | - Susanne Scheffknecht
- Department of Integrative Biology and Biodiversity Research, Institute of Botany, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Jan-Peter George
- Department of Forest Genetics, Federal Research and Training Centre for Forests, Natural Hazards and Landscape, Vienna, Austria
- Faculty of Science and Technology, University of Tartu, Tartu, Estonia
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12
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Weithmann G, Link RM, Banzragch BE, Würzberg L, Leuschner C, Schuldt B. Soil water availability and branch age explain variability in xylem safety of European beech in Central Europe. Oecologia 2022; 198:629-644. [PMID: 35212818 PMCID: PMC8956530 DOI: 10.1007/s00442-022-05124-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 01/24/2022] [Indexed: 12/17/2022]
Abstract
Xylem embolism resistance has been identified as a key trait with a causal relation to drought-induced tree mortality, but not much is known about its intra-specific trait variability (ITV) in dependence on environmental variation. We measured xylem safety and efficiency in 300 European beech (Fagus sylvatica L.) trees across 30 sites in Central Europe, covering a precipitation reduction from 886 to 522 mm year−1. A broad range of variables that might affect embolism resistance in mature trees, including climatic and soil water availability, competition, and branch age, were examined. The average P50 value varied by up to 1 MPa between sites. Neither climatic aridity nor structural variables had a significant influence on P50. However, P50 was less negative for trees with a higher soil water storage capacity, and positively related to branch age, while specific conductivity (Ks) was not significantly associated with either of these variables. The greatest part of the ITV for xylem safety and efficiency was attributed to random variability within populations. We conclude that the influence of site water availability on P50 and Ks is low in European beech, and that the high degree of within-population variability for P50, partly due to variation in branch age, hampers the identification of a clear environmental signal.
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Affiliation(s)
- Greta Weithmann
- Plant Ecology, Albrecht Von Haller Institute for Plant Sciences, University of Goettingen, Untere Karspüle 2, 37073, Göttingen, Germany
| | - Roman M Link
- Plant Ecology, Albrecht Von Haller Institute for Plant Sciences, University of Goettingen, Untere Karspüle 2, 37073, Göttingen, Germany.,Ecophysiology and Vegetation Ecology, Julius-von-Sachs-Institute of Biological Sciences, University of Würzburg, Julius-von-Sachs-Platz, 97082, Würzburg, Germany
| | - Bat-Enerel Banzragch
- Plant Ecology, Albrecht Von Haller Institute for Plant Sciences, University of Goettingen, Untere Karspüle 2, 37073, Göttingen, Germany
| | - Laura Würzberg
- Plant Ecology, Albrecht Von Haller Institute for Plant Sciences, University of Goettingen, Untere Karspüle 2, 37073, Göttingen, Germany
| | - Christoph Leuschner
- Plant Ecology, Albrecht Von Haller Institute for Plant Sciences, University of Goettingen, Untere Karspüle 2, 37073, Göttingen, Germany.,Centre for Biodiversity and Sustainable Land Use (CBL), University of Goettingen, 37075, Göttingen, Germany
| | - Bernhard Schuldt
- Plant Ecology, Albrecht Von Haller Institute for Plant Sciences, University of Goettingen, Untere Karspüle 2, 37073, Göttingen, Germany. .,Ecophysiology and Vegetation Ecology, Julius-von-Sachs-Institute of Biological Sciences, University of Würzburg, Julius-von-Sachs-Platz, 97082, Würzburg, Germany.
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13
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Benson MC, Miniat CF, Oishi AC, Denham SO, Domec JC, Johnson DM, Missik JE, Phillips RP, Wood JD, Novick KA. The xylem of anisohydric Quercus alba L. is more vulnerable to embolism than isohydric codominants. PLANT, CELL & ENVIRONMENT 2022; 45:329-346. [PMID: 34902165 DOI: 10.1111/pce.14244] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 12/01/2021] [Accepted: 12/08/2021] [Indexed: 06/14/2023]
Abstract
The coordination of plant leaf water potential (ΨL ) regulation and xylem vulnerability to embolism is fundamental for understanding the tradeoffs between carbon uptake and risk of hydraulic damage. There is a general consensus that trees with vulnerable xylem more conservatively regulate ΨL than plants with resistant xylem. We evaluated if this paradigm applied to three important eastern US temperate tree species, Quercus alba L., Acer saccharum Marsh. and Liriodendron tulipifera L., by synthesizing 1600 ΨL observations, 122 xylem embolism curves and xylem anatomical measurements across 10 forests spanning pronounced hydroclimatological gradients and ages. We found that, unexpectedly, the species with the most vulnerable xylem (Q. alba) regulated ΨL less strictly than the other species. This relationship was found across all sites, such that coordination among traits was largely unaffected by climate and stand age. Quercus species are perceived to be among the most drought tolerant temperate US forest species; however, our results suggest their relatively loose ΨL regulation in response to hydrologic stress occurs with a substantial hydraulic cost that may expose them to novel risks in a more drought-prone future.
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Affiliation(s)
- Michael C Benson
- O'Neill School of Public and Environmental Affairs, Indiana University Bloomington, Bloomington, Indiana, USA
| | - Chelcy F Miniat
- USDA Forest Service, Southern Research Station, Coweeta Hydrologic Laboratory, Otto, North Carolina, USA
| | - Andrew C Oishi
- USDA Forest Service, Southern Research Station, Coweeta Hydrologic Laboratory, Otto, North Carolina, USA
| | - Sander O Denham
- O'Neill School of Public and Environmental Affairs, Indiana University Bloomington, Bloomington, Indiana, USA
| | - Jean-Christophe Domec
- Bordeaux Sciences Agro, INRA UMR 1391 ISPA, Gradignan, France
- Nicholas School of the Environment, Duke University, Durham, North Carolina, USA
| | - Daniel M Johnson
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, Georgia, USA
| | - Justine E Missik
- Department of Civil, Environmental and Geodetic Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Richard P Phillips
- Department of Biology, Indiana University Bloomington, Bloomington, Indiana, USA
| | - Jeffrey D Wood
- University of Missouri, School of Natural Resources, Columbia, Missouri, USA
| | - Kimberly A Novick
- O'Neill School of Public and Environmental Affairs, Indiana University Bloomington, Bloomington, Indiana, USA
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14
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Zhang J, Gao Y, Feng M, Cui Y, Li S, Liu L, Wang Y, Xu W, Li F. Genome-Wide Identification of the HD-ZIP III Subfamily in Upland Cotton Reveals the Involvement of GhHB8-5D in the Biosynthesis of Secondary Wall in Fiber and Drought Resistance. FRONTIERS IN PLANT SCIENCE 2022; 12:806195. [PMID: 35154197 PMCID: PMC8828970 DOI: 10.3389/fpls.2021.806195] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Accepted: 12/20/2021] [Indexed: 05/24/2023]
Abstract
A subfamily of transcription factors known as HD-ZIP III plays distinct roles in the secondary cell wall biosynthesis, which could be attributed to the quality of cotton fiber and adaptation to drought stress. In this study, 18 HD-ZIP III genes were identified as genome wide from the upland cotton (Gossypium hirsutum). These genes are distributed on 14 different chromosomes, and all of them have undergone segmental duplications. Numerous cis-elements were identified in the promoter regions, which are related to phytohormone responses and abiotic stresses. Expression profiling of these genes by quantitative real-time (qRT)-PCR illustrated their differential spatial expression, with preferential expression in cotton fiber. Among these genes, GhHB8-5D was predicted to encode a protein that is targeted to the cell nucleus and having self-activation ability. In addition, the ectopic expression of GhHB8-5D or its synonymous mutant GhHB8-5Dm in Arabidopsis resulted in stunted plant growth, curly leaves, and twisted inflorescence stems. Microscopy examination revealed that the morphology of vascular bundles and deposition of secondary wall had substantially altered in stems, which is concomitant with the significant alteration in the transcription levels of secondary wall-related genes in these transgenic Arabidopsis. Further, ectopic expression of GhHB8-5D or GhHB8-5Dm in Arabidopsis also led to significant increase in green seedling rate and reduction in root length relative to wild type when the plants were grown under mimicked drought stress conditions. Taken together, our results may shed new light on the functional roles of GhHB8-5D that is attributable for secondary cell wall thickening in response to drought stress. Such a finding may facilitate a novel strategy for improving plant adaptations to environmental changes via regulating the biosynthesis of secondary cell wall.
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Affiliation(s)
- Jie Zhang
- State Key Laboratory of Cotton Biology, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang, China
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, School of Agricultural Sciences, Zhengzhou University, Zhengzhou, China
| | - Yanan Gao
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, School of Agricultural Sciences, Zhengzhou University, Zhengzhou, China
| | - Mengru Feng
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, School of Agricultural Sciences, Zhengzhou University, Zhengzhou, China
| | - Yuke Cui
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, School of Agricultural Sciences, Zhengzhou University, Zhengzhou, China
| | - Shuaijie Li
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, School of Agricultural Sciences, Zhengzhou University, Zhengzhou, China
| | - Le Liu
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, School of Agricultural Sciences, Zhengzhou University, Zhengzhou, China
| | - Ye Wang
- State Key Laboratory of Cotton Biology, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang, China
| | - Wenliang Xu
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Fuguang Li
- State Key Laboratory of Cotton Biology, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang, China
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, School of Agricultural Sciences, Zhengzhou University, Zhengzhou, China
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15
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Brookbank BP, Patel J, Gazzarrini S, Nambara E. Role of Basal ABA in Plant Growth and Development. Genes (Basel) 2021; 12:genes12121936. [PMID: 34946886 PMCID: PMC8700873 DOI: 10.3390/genes12121936] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 11/27/2021] [Accepted: 11/28/2021] [Indexed: 01/01/2023] Open
Abstract
Abscisic acid (ABA) regulates various aspects of plant physiology, including promoting seed dormancy and adaptive responses to abiotic and biotic stresses. In addition, ABA plays an im-portant role in growth and development under non-stressed conditions. This review summarizes phenotypes of ABA biosynthesis and signaling mutants to clarify the roles of basal ABA in growth and development. The promotive and inhibitive actions of ABA in growth are characterized by stunted and enhanced growth of ABA-deficient and insensitive mutants, respectively. Growth regulation by ABA is both promotive and inhibitive, depending on the context, such as concentrations, tissues, and environmental conditions. Basal ABA regulates local growth including hyponastic growth, skotomorphogenesis and lateral root growth. At the cellular level, basal ABA is essential for proper chloroplast biogenesis, central metabolism, and expression of cell-cycle genes. Basal ABA also regulates epidermis development in the shoot, by inhibiting stomatal development, and deposition of hydrophobic polymers like a cuticular wax layer covering the leaf surface. In the root, basal ABA is involved in xylem differentiation and suberization of the endodermis. Hormone crosstalk plays key roles in growth and developmental processes regulated by ABA. Phenotypes of ABA-deficient and insensitive mutants indicate prominent functions of basal ABA in plant growth and development.
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Affiliation(s)
- Benjamin P. Brookbank
- Department of Cells and Systems Biology, University of Toronto, Toronto, ON M3S 3G5, Canada; (B.P.B.); (J.P.)
| | - Jasmin Patel
- Department of Cells and Systems Biology, University of Toronto, Toronto, ON M3S 3G5, Canada; (B.P.B.); (J.P.)
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON M1C 1A4, Canada
| | - Sonia Gazzarrini
- Department of Cells and Systems Biology, University of Toronto, Toronto, ON M3S 3G5, Canada; (B.P.B.); (J.P.)
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON M1C 1A4, Canada
- Correspondence: (S.G.); (E.N.)
| | - Eiji Nambara
- Department of Cells and Systems Biology, University of Toronto, Toronto, ON M3S 3G5, Canada; (B.P.B.); (J.P.)
- Correspondence: (S.G.); (E.N.)
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16
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Assessing the Impact of Soil Moisture on Canopy Transpiration Using a Modified Jarvis-Stewart Model. WATER 2021. [DOI: 10.3390/w13192720] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
In dryland regions, soil moisture is an important limiting factor for canopy transpiration (T). Thus, clarifying the impact of soil moisture on T is critical for comprehensive forest—water management and sustainable development. In this study, T, meteorological factors (reference evapotranspiration, ETref), soil moisture (relative soil water content, RSWC), and leaf area index (LAI) in a Larix principis-rupprechtii plantation of Liupan Mountains in the dryland region of Northwest China were simultaneously monitored during the growing seasons in 2017–2019. A modified Jarvis—Stewart model was established by introducing the impact of RSWC in different soil layers (0–20, 20–40, and 40–60 cm, respectively) to quantify the independent contribution of RSWC of different soil layers to T. Results showed that with rising ETref, T firstly increased and then decreased, and with rising RSWC and LAI, T firstly increased and then gradually stabilised, respectively. The modified Jarvis—Stewart model was able to give comparable estimates of T to those derived from sap flow measurements. The contribution of RSWC to T in different soil layers has obvious specificity, and the contribution rate of 20–40 cm (13.4%) and 0–20 cm soil layers (6.6%) where roots are mainly distributed is significantly higher than that of 40–60 cm soil layer (1.9%). As the soil moisture status changes from moist (RSWC0–60cm ≥ 0.4) to drought (RSWC0–60cm < 0.4), the role of the soil moisture in the 0–20 cm soil layer increased compared with other layers. The impacts of soil moisture that were coupled into the Jarvis—Stewart model can genuinely reflect the environmental influence and can be used to quantify the contributions of soil moisture to T. Thus, it has the potential to become a new tool to guide the protection and management of forest water resources.
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17
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Sorek Y, Greenstein S, Netzer Y, Shtein I, Jansen S, Hochberg U. An increase in xylem embolism resistance of grapevine leaves during the growing season is coordinated with stomatal regulation, turgor loss point and intervessel pit membranes. THE NEW PHYTOLOGIST 2021; 229:1955-1969. [PMID: 33098088 DOI: 10.1111/nph.17025] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 10/02/2020] [Indexed: 05/27/2023]
Abstract
Although xylem embolism resistance is traditionally considered as static, we hypothesized that in grapevine (Vitis vinifera) leaf xylem becomes more embolism-resistant over the growing season. We evaluated xylem architecture, turgor loss point (ΨTLP ) and water potentials leading to 25% of maximal stomatal conductance (gs25 ) or 50% embolism in the leaf xylem (P50 ) in three irrigation treatments and at three time points during the growing season, while separating the effects of leaf age and time of season. Hydraulic traits acclimated over the growing season in a coordinated manner. Without irrigation, ΨTLP , gs25 , and P50 decreased between late May and late August by 0.95, 0.77 and 0.71 MPa, respectively. A seasonal shift in P50 occurred even in mature leaves, while irrigation had only a mild effect (< 0.2 MPa) on P50 . Vessel size and pit membrane thickness were also seasonally dynamic, providing a plausible explanation for the shift in P50 . Our findings provide clear evidence that grapevines can modify their hydraulic traits along a growing season to allow lower xylem water potential, without compromising gas exchange, leaf turgor or xylem integrity. Seasonal changes should be considered when modeling ecosystem vulnerability to drought or comparing datasets acquired at different phenological stages.
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Affiliation(s)
- Yonatan Sorek
- Institute of Soil, Water and Environmental Science, Volcani Center, Agricultural Research Organization, PO Box 6, Bet-Dagan, 50250, Israel
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, 76100, Israel
| | - Smadar Greenstein
- Institute of Soil, Water and Environmental Science, Volcani Center, Agricultural Research Organization, PO Box 6, Bet-Dagan, 50250, Israel
| | - Yishai Netzer
- Department of Chemical engineering, Ariel University, Ariel, 40700, Israel
- Agriculture and Oenology Department, Eastern R&D Center, Ariel, 40700, Israel
| | - Ilana Shtein
- Agriculture and Oenology Department, Eastern R&D Center, Ariel, 40700, Israel
| | - Steven Jansen
- Institute of Systematic Botany and Ecology, Ulm University, Albert-Einstein-Allee 11, Ulm, D-89081, Germany
| | - Uri Hochberg
- Institute of Soil, Water and Environmental Science, Volcani Center, Agricultural Research Organization, PO Box 6, Bet-Dagan, 50250, Israel
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18
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Bittencourt PRL, Oliveira RS, da Costa ACL, Giles AL, Coughlin I, Costa PB, Bartholomew DC, Ferreira LV, Vasconcelos SS, Barros FV, Junior JAS, Oliveira AAR, Mencuccini M, Meir P, Rowland L. Amazonia trees have limited capacity to acclimate plant hydraulic properties in response to long-term drought. GLOBAL CHANGE BIOLOGY 2020; 26:3569-3584. [PMID: 32061003 DOI: 10.1111/gcb.15040] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 12/30/2019] [Accepted: 02/02/2020] [Indexed: 05/29/2023]
Abstract
The fate of tropical forests under future climate change is dependent on the capacity of their trees to adjust to drier conditions. The capacity of trees to withstand drought is likely to be determined by traits associated with their hydraulic systems. However, data on whether tropical trees can adjust hydraulic traits when experiencing drought remain rare. We measured plant hydraulic traits (e.g. hydraulic conductivity and embolism resistance) and plant hydraulic system status (e.g. leaf water potential, native embolism and safety margin) on >150 trees from 12 genera (36 species) and spanning a stem size range from 14 to 68 cm diameter at breast height at the world's only long-running tropical forest drought experiment. Hydraulic traits showed no adjustment following 15 years of experimentally imposed moisture deficit. This failure to adjust resulted in these drought-stressed trees experiencing significantly lower leaf water potentials, and higher, but variable, levels of native embolism in the branches. This result suggests that hydraulic damage caused by elevated levels of embolism is likely to be one of the key drivers of drought-induced mortality following long-term soil moisture deficit. We demonstrate that some hydraulic traits changed with tree size, however, the direction and magnitude of the change was controlled by taxonomic identity. Our results suggest that Amazonian trees, both small and large, have limited capacity to acclimate their hydraulic systems to future droughts, potentially making them more at risk of drought-induced mortality.
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Affiliation(s)
- Paulo R L Bittencourt
- College of Life and Environmental Sciences, University of Exeter, Exeter, UK
- Instituto de Biologia, University of Campinas (UNICAMP), Campinas, Brazil
| | - Rafael S Oliveira
- Instituto de Biologia, University of Campinas (UNICAMP), Campinas, Brazil
- Biological Sciences, UWA, Perth, WA, Australia
| | | | - Andre L Giles
- Instituto de Biologia, University of Campinas (UNICAMP), Campinas, Brazil
| | - Ingrid Coughlin
- Departamento de Biologia, FFCLRP, Universidade de São Paulo, Ribeirão Preto, Brazil
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Patricia B Costa
- Instituto de Biologia, University of Campinas (UNICAMP), Campinas, Brazil
- Biological Sciences, UWA, Perth, WA, Australia
| | - David C Bartholomew
- College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | | | | | - Fernanda V Barros
- College of Life and Environmental Sciences, University of Exeter, Exeter, UK
- Instituto de Biologia, University of Campinas (UNICAMP), Campinas, Brazil
| | - Joao A S Junior
- Instituto de Biologia, University of Campinas (UNICAMP), Campinas, Brazil
| | | | | | - Patrick Meir
- Research School of Biology, Australian National University, Canberra, ACT, Australia
- School of GeoSciences, University of Edinburgh, Edinburgh, UK
| | - Lucy Rowland
- College of Life and Environmental Sciences, University of Exeter, Exeter, UK
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19
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Differences in Near Isohydric and Anisohydric Behavior of Contrasting Poplar Hybrids (I-101 (Populus alba L.) × 84K (Populus alba L. × Populus glandulosa Uyeki)) under Drought-Rehydration Treatments. FORESTS 2020. [DOI: 10.3390/f11040402] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Carbon starvation and hydraulic failure are considered important factors in determining the mechanisms associated with tree mortality. In this study, iso/anisohydric classification was used to assess drought resistance and mortality mechanisms in two contrasting poplar species, as it is generally believed that isohydric species are more susceptible to carbon starvation, while anisohydric species are more susceptible to hydraulic failure. However, these assumptions are rarely tested in poplar genotypes with contrasting growth strategies. Thus, we subjected potted poplar genotypes (I-101 (Populus alba L.) × 84K (Populus alba L. × Populus glandulosa Uyeki)) with fast and slow growth rates to drought–rehydration treatments. The slow-growing genotype maintained higher stomatal conductance and lower predawn leaf water potential than the fast-growing genotype, thus exhibiting a near-anisohydric stomatal behavior throughout the treatment period. The nonstructural carbohydrate (NSC) content indicated that the two genotypes had the same trend of carbon change (e.g., the NSC content in the leaves increased with drought and then decreased). However, when NSC content data were combined with the growth and photosynthetic data, it was observed that the slow-growing genotype mobilized carbon to maintain hydraulic safety, while the NSC content of the fast-growing genotype among tissues was static. The percent loss of hydraulic conductivity in the branches during treatments indicated that the fast-growing genotype could recover more quickly from xylem embolism than the slow-growing genotype. The slow-growing genotype with a slow growth recovery after rehydration showed a significant increase in carbon consumption, combined with a significant increase in the hydraulic safety threshold value, indicating that there may be drought tolerance. In comparison, the fast-growing genotype showed a faster hydraulic recovery ability that had no effect on the NSC content in the leaves and roots. Our findings demonstrate intraspecific isohydric behavior in poplar; however, the trade-off between carbon distribution and stomatal regulation should be considered separately within genotypes of the same species. In addition, NSC plays an important role in water–carbon balance in the drought–rehydration cycle.
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20
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Oyiga BC, Palczak J, Wojciechowski T, Lynch JP, Naz AA, Léon J, Ballvora A. Genetic components of root architecture and anatomy adjustments to water-deficit stress in spring barley. PLANT, CELL & ENVIRONMENT 2020; 43:692-711. [PMID: 31734943 DOI: 10.1111/pce.13683] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 11/06/2019] [Accepted: 11/13/2019] [Indexed: 05/26/2023]
Abstract
Roots perform vital roles for adaptation and productivity under water-deficit stress, even though their specific functions are poorly understood. In this study, the genetic control of the nodal-root architectural and anatomical response to water deficit were investigated among diverse spring barley accessions. Water deficit induced substantial variations in the nodal root traits. The cortical, stele, and total root cross-sectional areas of the main-shoot nodal roots decreased under water deficit, but increased in the tiller nodal roots. Root xylem density and arrested nodal roots increased under water deficit, with the formation of root suberization/lignification and large cortical aerenchyma. Genome-wide association study implicated 11 QTL intervals in the architectural and anatomical nodal root response to water deficit. Among them, three and four QTL intervals had strong effects across seasons and on both root architectural and anatomical traits, respectively. Genome-wide epistasis analysis revealed 44 epistatically interacting SNP loci. Further analyses showed that these QTL intervals contain important candidate genes, including ZIFL2, MATE, and PPIB, whose functions are shown to be related to the root adaptive response to water deprivation in plants. These results give novel insight into the genetic architectures of barley nodal root response to soil water deficit stress in the fields, and thus offer useful resources for root-targeted marker-assisted selection.
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Affiliation(s)
| | | | - Tobias Wojciechowski
- Forschungszentrum Jülich, Institute for Bio- and Geosciences (Plant Sciences), Bonn, Germany
| | - Jonathan P Lynch
- Department of Plant Science, The Pennsylvania State, State College, Pennsylvania
| | - Ali A Naz
- INRES-Plant Breeding, University of Bonn, Bonn, Germany
| | - Jens Léon
- INRES-Plant Breeding, University of Bonn, Bonn, Germany
| | - Agim Ballvora
- INRES-Plant Breeding, University of Bonn, Bonn, Germany
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21
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Liu J, Kang S, Davies WJ, Ding R. Elevated [CO 2 ] alleviates the impacts of water deficit on xylem anatomy and hydraulic properties of maize stems. PLANT, CELL & ENVIRONMENT 2020; 43:563-578. [PMID: 31721225 DOI: 10.1111/pce.13677] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Accepted: 11/06/2019] [Indexed: 05/15/2023]
Abstract
Plants can modify xylem anatomy and hydraulic properties to adjust to water status. Elevated [CO2 ] can increase plant water potential via reduced stomatal conductance and water loss. This raises the question of whether elevated [CO2 ], which thus improves plant water status, will reduce the impacts of soil water deficit on xylem anatomy and hydraulic properties of plants. To analyse the impacts of water and [CO2 ] on maize stem xylem anatomy and hydraulic properties, we exposed potted maize plants to varying [CO2 ] levels (400, 700, 900, and 1,200 ppm) and water levels (full irrigation and deficit irrigation). Results showed that at current [CO2 ], vessel diameter, vessel roundness, stem cross-section area, specific hydraulic conductivity, and vulnerability to embolism decreased under deficit irrigation; yet, these impacts of deficit irrigation were reduced at elevated [CO2 ]. Across all treatments, midday stem water potential was tightly correlated with xylem traits and displayed similar responses. A distinct trade-off between efficiency and safety in stem xylem water transportation in response to water deficit was observed at current [CO2 ] but not observed at elevated [CO2 ]. The results of this study enhance our knowledge of plant hydraulic acclimation under future climate environments and provide insights into trade-offs in xylem structure and function.
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Affiliation(s)
- Junzhou Liu
- Center for Agricultural Water Research in China, China Agricultural University, Beijing, 100083, China
- Shiyanghe Experimental Station for Improving Water Use Efficiency in Agriculture, Ministry of Agriculture and Rural Affairs, Beijing, 100125, China
| | - Shaozhong Kang
- Center for Agricultural Water Research in China, China Agricultural University, Beijing, 100083, China
- Shiyanghe Experimental Station for Improving Water Use Efficiency in Agriculture, Ministry of Agriculture and Rural Affairs, Beijing, 100125, China
| | - William J Davies
- Lancaster Environment Centre, Lancaster University, Bailrigg, LA1 4YQ, UK
| | - Risheng Ding
- Center for Agricultural Water Research in China, China Agricultural University, Beijing, 100083, China
- Shiyanghe Experimental Station for Improving Water Use Efficiency in Agriculture, Ministry of Agriculture and Rural Affairs, Beijing, 100125, China
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22
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Li S, Wang J, Yin Y, Li X, Deng L, Jiang X, Chen Z, Li Y. Investigating Effects of Bordered Pit Membrane Morphology and Properties on Plant Xylem Hydraulic Functions-A Case Study from 3D Reconstruction and Microflow Modelling of Pit Membranes in Angiosperm Xylem. PLANTS (BASEL, SWITZERLAND) 2020; 9:E231. [PMID: 32054100 PMCID: PMC7076482 DOI: 10.3390/plants9020231] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 01/18/2020] [Accepted: 02/08/2020] [Indexed: 01/12/2023]
Abstract
Pit membranes in between neighboring conduits of xylem play a crucial role in plant water transport. In this review, the morphological characteristics, chemical composition and mechanical properties of bordered pit membranes were summarized and linked with their functional roles in xylem hydraulics. The trade-off between xylem hydraulic efficiency and safety was closely related with morphology and properties of pit membranes, and xylem embolism resistance was also determined by the pit membrane morphology and properties. Besides, to further investigate the effects of bordered pit membranes morphology and properties on plant xylem hydraulic functions, here we modelled three-dimensional structure of bordered pit membranes by applying a deposition technique. Based on reconstructed 3D pit membrane structures, a virtual fibril network was generated to model the microflow pattern across inter-vessel pit membranes. Moreover, the mechanical behavior of intervessel pit membranes was estimated from a single microfibril's mechanical property. Pit membranes morphology varied among different angiosperm and gymnosperm species. Our modelling work suggested that larger pores of pit membranes do not necessarily contribute to major flow rate across pit membranes; instead, the obstructed degree of flow pathway across the pit membranes plays a more important role. Our work provides useful information for studying the mechanism of microfluid flow transport across pit membranes and also sheds light on investigating the response of pit membranes both at normal and stressed conditions, thus improving our understanding on functional roles of pit membranes in xylem hydraulic function. Further work could be done to study the morphological and mechanical response of bordered pit membranes under different dehydrated conditions, as well as the related microflow behavior, based on our constructed model.
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Affiliation(s)
- Shan Li
- Department of Wood Anatomy and Utilization, Research Institute of Wood Industry, Chinese Academy of Forestry, Beijing 100091, China; (S.L.); (J.W.); (Y.Y.); (L.D.); (X.J.)
- Wood Collections (WOODPEDIA), Chinese Academy of Forestry, Beijing 100091, China
| | - Jie Wang
- Department of Wood Anatomy and Utilization, Research Institute of Wood Industry, Chinese Academy of Forestry, Beijing 100091, China; (S.L.); (J.W.); (Y.Y.); (L.D.); (X.J.)
- Wood Collections (WOODPEDIA), Chinese Academy of Forestry, Beijing 100091, China
| | - Yafang Yin
- Department of Wood Anatomy and Utilization, Research Institute of Wood Industry, Chinese Academy of Forestry, Beijing 100091, China; (S.L.); (J.W.); (Y.Y.); (L.D.); (X.J.)
- Wood Collections (WOODPEDIA), Chinese Academy of Forestry, Beijing 100091, China
| | - Xin Li
- College of Forestry, Beijing Forestry University, Beijing 100083, China;
| | - Liping Deng
- Department of Wood Anatomy and Utilization, Research Institute of Wood Industry, Chinese Academy of Forestry, Beijing 100091, China; (S.L.); (J.W.); (Y.Y.); (L.D.); (X.J.)
- International Center for Bamboo and Rattan, Beijing 100102, China
| | - Xiaomei Jiang
- Department of Wood Anatomy and Utilization, Research Institute of Wood Industry, Chinese Academy of Forestry, Beijing 100091, China; (S.L.); (J.W.); (Y.Y.); (L.D.); (X.J.)
- Wood Collections (WOODPEDIA), Chinese Academy of Forestry, Beijing 100091, China
| | - Zhicheng Chen
- Institute of New Forestry Technology, Chinese Academy of Forestry, Beijing 100083, China;
| | - Yujun Li
- School of Mechanical Engineering, Northwestern Polytechnical University, Xi’an 710072, China
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23
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Matzner SL, Ronning N, Hawkinson J, Cummiskey T, Buchanan J, Miller E, Carlisle G. Does acclimation in cavitation resistance due to mechanical perturbation support the pit area or conduit reinforcement hypotheses in Phaseolus vulgaris? PHYSIOLOGIA PLANTARUM 2019; 167:378-390. [PMID: 30537192 PMCID: PMC6557702 DOI: 10.1111/ppl.12895] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 12/01/2018] [Accepted: 12/04/2018] [Indexed: 05/23/2023]
Abstract
Two Phaseolus vulgaris L. cultivars were exposed to reduced water and stem mechanical perturbation treatments (flexing) to determine if acclimation to these treatments induced hydraulic changes, altered cavitation resistance and changed stem mechanical properties. Additionally, this study sought to determine if changes in cavitation resistance would support the pit area or conduit reinforcement hypotheses. Flexing reduced biomass, leaf area, xylem vessel area and hydraulic conductivity. One cultivar had greater measures of stem strength and cavitation resistance. Flexing increased cavitation resistance (P50 ) but did not increase Young's modulus, rigidity or flexural strength on dried stems. Stem rigidity and basal diameter were correlated with leaf mass. The ratio of conduit wall thickness to span [(t/b)h 2 ] increased under high water and flexing treatments while rigidity decreased for one cultivar exposed to both flexing and lower water suggesting an inability to compensate for two simultaneous stresses. Although P50 was not correlated with measures of mechanical strength, P50 was correlated with vessel diameter, consistent with the pit area hypothesis. This study confirmed that mechanical perturbation can impact xylem structural properties and result in altered plant water flow characteristics and cavitation resistance. Long-term hydraulic acclimation in these herbaceous annuals was constrained by similar tradeoffs that constrain hydraulic properties across species.
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Drought Enhances the Role of Competition in Mediating the Relationship between Tree Growth and Climate in Semi-Arid Areas of Northwest China. FORESTS 2019. [DOI: 10.3390/f10090804] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Climate variability can exert a powerful impact on biotic competition, but past studies have focused largely on short-lived species, with a lack of attention to long-lived species such as trees. Therefore, there is a need to evaluate how competition regulates the climate-growth relationship in mature trees. We sampled the dominant tree species, Picea wilsonii Mast., on Xinglong Mountain, China, and studied the above issues by analyzing the relationship between tree radial growth, precipitation, and competition. In relatively wet years (precipitation > average), there was no significant difference in climate sensitivity between different competition classes. However, trees suffering from highly competitive stress were more sensitive to climate variability in all years, and particularly in the subset of years that was relatively drought (precipitation < average). These results suggest that competition enhances its ability to regulate tree growth response to climate variability in adverse weather conditions. Competition for resources between trees was asymmetrical, and an increase in height could give trees a disproportionate benefit. Thus, at trunk-level, both basal area incremental growth and intrinsic water-use efficiency of trees subjected to low competitive stress were significantly higher than trees that are subjected to highly competitive stress. Although the intrinsic water-use efficiency of trees under highly competitive stress increased more rapidly as the drought level increases, this did not change the fact that the radial growth of them declined more. Our research is valuable for the development of individual-tree growth models and advances our understanding for forest management under global climate change.
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What Makes the Wood? Exploring the Molecular Mechanisms of Xylem Acclimation in Hardwoods to an Ever-Changing Environment. FORESTS 2019. [DOI: 10.3390/f10040358] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Wood, also designated as secondary xylem, is the major structure that gives trees and other woody plants stability for upright growth and maintains the water supply from the roots to all other plant tissues. Over recent decades, our understanding of the cellular processes of wood formation (xylogenesis) has substantially increased. Plants as sessile organisms face a multitude of abiotic stresses, e.g., heat, drought, salinity and limiting nutrient availability that require them to adjust their wood structure to maintain stability and water conductivity. Because of global climate change, more drastic and sudden changes in temperature and longer periods without precipitation are expected to impact tree productivity in the near future. Thus, it is essential to understand the process of wood formation in trees under stress. Many traits, such as vessel frequency and size, fiber thickness and density change in response to different environmental stimuli. Here, we provide an overview of our current understanding of how abiotic stress factors affect wood formation on the molecular level focussing on the genes that have been identified in these processes.
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Rosner S, Heinze B, Savi T, Dalla‐Salda G. Prediction of hydraulic conductivity loss from relative water loss: new insights into water storage of tree stems and branches. PHYSIOLOGIA PLANTARUM 2019; 165:843-854. [PMID: 29923608 PMCID: PMC7379737 DOI: 10.1111/ppl.12790] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2018] [Revised: 06/04/2018] [Accepted: 06/15/2018] [Indexed: 05/23/2023]
Abstract
More frequently occurring, drought waves call for a deeper understanding of tree hydraulics and fast and easily applicable methods to measure drought stress. The aim of this study was to establish empirical relationships between the percent loss of hydraulic conductivity (PLC) and the relative water loss (RWL) in woody stem axes with different P50 , i.e. the water potential (Ψ) that causes 50% conductivity loss. Branches and saplings of temperate conifer (Picea abies, Larix decidua) and angiosperm species (Acer campestre, Fagus sylvatica, Populus x canescens, Populus tremula, Sorbus torminalis) and trunk wood of mature P. abies trees were analyzed. P50 was calculated from hydraulic measurements following bench top dehydration or air injection. RWL and PLC were fitted by linear, quadratic or cubic equations. Species- or age-specific RWLs at P50 varied between 10 and 25% and P88 , the Ψ that causes 88% conductivity loss, between 18 and 44%. P50 was predicted from the relationship between Ψ and the RWL. The predictive quality for P50 across species was almost 1:1 (r2 = 0.99). The approach presented allows thus reliable and fast prediction of PLC from RWL. Branches and saplings with high hydraulic vulnerability tended to have lower RWLs at P50 and at P88 . The results are discussed with regard to the different water storage capacities in sapwood and survival strategies under drought stress. Potential applications are screening trees for drought sensitivity and a fast interpretation of diurnal, seasonal or drought induced changes in xylem water content upon their impact on conductivity loss.
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Affiliation(s)
- Sabine Rosner
- Institute of BotanyBOKU University ViennaGregor Mendel Straße 33, 1180ViennaAustria
| | - Berthold Heinze
- Department of Forest Genetics, Federal Research and Training Centre for ForestsNatural Hazards and LandscapeSeckendorff-Gudent-Weg 8, 1130ViennaAustria
| | - Tadeja Savi
- Institute of BotanyBOKU University ViennaGregor Mendel Straße 33, 1180ViennaAustria
- Division of Viticulture and PomologyBOKU University ViennaKonrad Lorenz‐Straβe 243430 Tulln an der DonauAustria
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Zhang X, Liu L, Chen B, Qin Z, Xiao Y, Zhang Y, Yao R, Liu H, Yang H. Progress in Understanding the Physiological and Molecular Responses of Populus to Salt Stress. Int J Mol Sci 2019; 20:ijms20061312. [PMID: 30875897 PMCID: PMC6471404 DOI: 10.3390/ijms20061312] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 03/08/2019] [Accepted: 03/09/2019] [Indexed: 11/25/2022] Open
Abstract
Salt stress (SS) has become an important factor limiting afforestation programs. Because of their salt tolerance and fully sequenced genomes, poplars (Populus spp.) are used as model species to study SS mechanisms in trees. Here, we review recent insights into the physiological and molecular responses of Populus to SS, including ion homeostasis and signaling pathways, such as the salt overly sensitive (SOS) and reactive oxygen species (ROS) pathways. We summarize the genes that can be targeted for the genetic improvement of salt tolerance and propose future research areas.
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Affiliation(s)
- Xiaoning Zhang
- Guangxi Key Laboratory of Superior Timber Trees Resource Cultivation, Guangxi Forestry Research Institute, 23 Yongwu Road, Nanning 530002, China.
| | - Lijun Liu
- Key Laboratory of State Forestry Administration for Silviculture of the lower Yellow River, College of Forestry, Shandong Agricultural University, Taian 271018, Shandong, China.
| | - Bowen Chen
- Guangxi Key Laboratory of Superior Timber Trees Resource Cultivation, Guangxi Forestry Research Institute, 23 Yongwu Road, Nanning 530002, China.
| | - Zihai Qin
- Guangxi Key Laboratory of Superior Timber Trees Resource Cultivation, Guangxi Forestry Research Institute, 23 Yongwu Road, Nanning 530002, China.
| | - Yufei Xiao
- Guangxi Key Laboratory of Superior Timber Trees Resource Cultivation, Guangxi Forestry Research Institute, 23 Yongwu Road, Nanning 530002, China.
| | - Ye Zhang
- Guangxi Key Laboratory of Superior Timber Trees Resource Cultivation, Guangxi Forestry Research Institute, 23 Yongwu Road, Nanning 530002, China.
| | - Ruiling Yao
- Guangxi Key Laboratory of Superior Timber Trees Resource Cultivation, Guangxi Forestry Research Institute, 23 Yongwu Road, Nanning 530002, China.
| | - Hailong Liu
- Guangxi Key Laboratory of Superior Timber Trees Resource Cultivation, Guangxi Forestry Research Institute, 23 Yongwu Road, Nanning 530002, China.
| | - Hong Yang
- Key Laboratory of Economic Plants and Biotechnology, Kunming Institute of Botany, Academy of Sciences, Yunnan Key Laboratory for Wild Plant Resources, Kunming 650201, China.
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28
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Feng J, Huang P, Wan X. Interactive effects of wind and light on growth and architecture of poplar saplings. Ecol Res 2019. [DOI: 10.1111/1440-1703.1013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Jinxia Feng
- Institute of New Forestry Technology Chinese Academy of Forestry Beijing China
| | - Ping Huang
- Institute of New Forestry Technology Chinese Academy of Forestry Beijing China
| | - Xianchong Wan
- Institute of New Forestry Technology Chinese Academy of Forestry Beijing China
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Ramachandran P, Wang G, Augstein F, de Vries J, Carlsbecker A. Continuous root xylem formation and vascular acclimation to water deficit involves endodermal ABA signalling via miR165. Development 2018; 145:dev.159202. [DOI: 10.1242/dev.159202] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Accepted: 01/09/2018] [Indexed: 12/22/2022]
Abstract
The plant root xylem comprises a specialized tissue for water distribution to the shoot. Despite its importance, its potential morphological plasticity in response to environmental conditions such as limited water availability has not been thoroughly studied. Here, we identify a role for the phytohormone abscisic acid (ABA) for proper xylem development and describe how ABA signalling-mediated effects on core developmental regulators are employed to alter xylem morphology under limited water availability in Arabidopsis. Plants with impaired ABA biosynthesis and reduced ABA signalling in the cell layer surrounding the vasculature displayed defects in xylem continuity, suggesting that non-cell autonomous ABA signalling is required for proper xylem development. Conversely, upon external ABA application or under limited water availability extra xylem strands were formed. The observed xylem developmental alterations were dependent on adequate endodermal ABA signalling, which activated MIR165A. This resulted in increased miR165 levels that repress target class III HD-ZIP transcription factors in the stele. We conclude that a pathway known to control core developmental features is employed as a means of modifying plant xylem morphology under conditions of environmental stress.
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Affiliation(s)
- Prashanth Ramachandran
- Department of Organismal Biology, Physiological Botany, Evolutionary Biology Centre and Linnean Centre for Plant Biology, Uppsala University, Ullsv. 24E, SE-75651 Uppsala, Sweden
| | - Guodong Wang
- Department of Organismal Biology, Physiological Botany, Evolutionary Biology Centre and Linnean Centre for Plant Biology, Uppsala University, Ullsv. 24E, SE-75651 Uppsala, Sweden
- Present address: Key Laboratory of Ministry of Education for Medicinal Plant Resource and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Developing of Endangered Chinese Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, China
| | - Frauke Augstein
- Department of Organismal Biology, Physiological Botany, Evolutionary Biology Centre and Linnean Centre for Plant Biology, Uppsala University, Ullsv. 24E, SE-75651 Uppsala, Sweden
| | - Jan de Vries
- Department of Organismal Biology, Physiological Botany, Evolutionary Biology Centre and Linnean Centre for Plant Biology, Uppsala University, Ullsv. 24E, SE-75651 Uppsala, Sweden
- Present address: Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, Canada
| | - Annelie Carlsbecker
- Department of Organismal Biology, Physiological Botany, Evolutionary Biology Centre and Linnean Centre for Plant Biology, Uppsala University, Ullsv. 24E, SE-75651 Uppsala, Sweden
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Zolfaghar S, Villalobos-Vega R, Cleverly J, Eamus D. Co-ordination among leaf water relations and xylem vulnerability to embolism of Eucalyptus trees growing along a depth-to-groundwater gradient. TREE PHYSIOLOGY 2015; 35:732-743. [PMID: 26023059 DOI: 10.1093/treephys/tpv039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Accepted: 04/19/2015] [Indexed: 06/04/2023]
Abstract
The importance of groundwater resources in arid and semi-arid areas for plant survival is well documented. However, there have been few studies examining the importance and impacts of groundwater availability in mesic environments. The aim of this study was to determine how depth-to-groundwater (DGW) impacts on leaf water relations, leaf structure and branch xylem vulnerability to embolism in a mesic environment. We hypothesize that increasing DGW results in increased resistance to drought stress and that this will be manifested across leaf and branch attributes pertaining to water relations. We further investigate whether there is co-ordination across leaf and branch-scale level responses to increased DGW. Four species were used in this study: Eucalyptus globoidea Blakely, E. piperita Sm., E. sclerophylla (Blakely) L.A.S.Johnson & Blaxell and E. sieberi L.A.S.Johnson. Six sites were chosen along an 11 km transect to span a range of average DGW: 2.4, 4.3, 9.8, 13, 16.3 and 37.5 m. Leaf water relations of trees showed less sensitivity to drought stress as DGW increased. This was reflected in significantly lower leaf turgor loss point and maximum osmotic potential, increased maximum turgor and a reduced leaf relative water content as DGW increased. At shallow DGW sites, minimum diurnal leaf water potentials were generally more negative than leaf water potential at zero turgor, but the reverse was observed at deep sites, indicating a larger growth potential safety margin at deep sites compared with shallow sites. Leaf cell wall elasticity varied independently of DGW. Xylem vulnerability to embolism was quantified as the water potential associated with 50% loss of conductance (P 50). In both summer and winter P 50 was significantly and negatively correlated with DGW. Co-ordination between leaf- and branch-level responses to increase in DGW was apparent, which strongly supports the conclusion that groundwater supply influenced woodland structure and functional behaviour.
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Affiliation(s)
- Sepideh Zolfaghar
- University of Technology Sydney, PO Box 123, Broadway, NSW, 2007, Australia National Centre for Groundwater Research and Training, University of Technology Sydney, PO BOX 123, Broadway, NSW, 2007, Australia
| | - Randol Villalobos-Vega
- University of Technology Sydney, PO Box 123, Broadway, NSW, 2007, Australia National Centre for Groundwater Research and Training, University of Technology Sydney, PO BOX 123, Broadway, NSW, 2007, Australia
| | - James Cleverly
- University of Technology Sydney, PO Box 123, Broadway, NSW, 2007, Australia National Centre for Groundwater Research and Training, University of Technology Sydney, PO BOX 123, Broadway, NSW, 2007, Australia
| | - Derek Eamus
- University of Technology Sydney, PO Box 123, Broadway, NSW, 2007, Australia National Centre for Groundwater Research and Training, University of Technology Sydney, PO BOX 123, Broadway, NSW, 2007, Australia
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Savi T, Bertuzzi S, Branca S, Tretiach M, Nardini A. Drought-induced xylem cavitation and hydraulic deterioration: risk factors for urban trees under climate change? THE NEW PHYTOLOGIST 2015; 205:1106-1116. [PMID: 25354036 DOI: 10.1111/nph.13112] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Accepted: 09/14/2014] [Indexed: 05/23/2023]
Abstract
Urban trees help towns to cope with climate warming by cooling both air and surfaces. The challenges imposed by the urban environment, with special reference to low water availability due to the presence of extensive pavements, result in high rates of mortality of street trees, that can be increased by climatic extremes. We investigated the water relations and xylem hydraulic safety/efficiency of Quercus ilex trees growing at urban sites with different percentages of surrounding impervious pavements. Seasonal changes of plant water potential and gas exchange, vulnerability to cavitation and embolism level, and morpho-anatomical traits were measured. We found patterns of increasing water stress and vulnerability to drought at increasing percentages of impervious pavement cover, with a consequent reduction in gas exchange rates, decreased safety margins toward embolism development, and increased vulnerability to cavitation, suggesting the occurrence of stress-induced hydraulic deterioration. The amount of impermeable surface and chronic exposure to water stress influence the site-specific risk of drought-induced dieback of urban trees under extreme drought. Besides providing directions for management of green spaces in towns, our data suggest that xylem hydraulics is key to a full understanding of the responses of urban trees to global change.
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Affiliation(s)
- Tadeja Savi
- Dipartimento di Scienze della Vita, Università di Trieste, Via L. Giorgieri 10, Trieste, 34127, Italy
| | - Stefano Bertuzzi
- Dipartimento di Scienze della Vita, Università di Trieste, Via L. Giorgieri 10, Trieste, 34127, Italy
| | - Salvatore Branca
- Dipartimento di Scienze della Vita, Università di Trieste, Via L. Giorgieri 10, Trieste, 34127, Italy
| | - Mauro Tretiach
- Dipartimento di Scienze della Vita, Università di Trieste, Via L. Giorgieri 10, Trieste, 34127, Italy
| | - Andrea Nardini
- Dipartimento di Scienze della Vita, Università di Trieste, Via L. Giorgieri 10, Trieste, 34127, Italy
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Mock KE, Callahan CM, Islam-Faridi MN, Shaw JD, Rai HS, Sanderson SC, Rowe CA, Ryel RJ, Madritch MD, Gardner RS, Wolf PG. Widespread triploidy in Western North American aspen (Populus tremuloides). PLoS One 2012; 7:e48406. [PMID: 23119006 PMCID: PMC3485218 DOI: 10.1371/journal.pone.0048406] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Accepted: 10/01/2012] [Indexed: 01/05/2023] Open
Abstract
We document high rates of triploidy in aspen (Populus tremuloides) across the western USA (up to 69% of genets), and ask whether the incidence of triploidy across the species range corresponds with latitude, glacial history (as has been documented in other species), climate, or regional variance in clone size. Using a combination of microsatellite genotyping, flow cytometry, and cytology, we demonstrate that triploidy is highest in unglaciated, drought-prone regions of North America, where the largest clone sizes have been reported for this species. While we cannot completely rule out a low incidence of undetected aneuploidy, tetraploidy or duplicated loci, our evidence suggests that these phenomena are unlikely to be significant contributors to our observed patterns. We suggest that the distribution of triploid aspen is due to a positive synergy between triploidy and ecological factors driving clonality. Although triploids are expected to have low fertility, they are hypothesized to be an evolutionary link to sexual tetraploidy. Thus, interactions between clonality and polyploidy may be a broadly important component of geographic speciation patterns in perennial plants. Further, cytotypes are expected to show physiological and structural differences which may influence susceptibility to ecological factors such as drought, and we suggest that cytotype may be a significant and previously overlooked factor in recent patterns of high aspen mortality in the southwestern portion of the species range. Finally, triploidy should be carefully considered as a source of variance in genomic and ecological studies of aspen, particularly in western U.S. landscapes.
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Affiliation(s)
- Karen E Mock
- Department of Wildland Resources, Utah State University, Logan, Utah, United States of America.
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Cochard H, Herbette S, Barigah T, Badel E, Ennajeh M, Vilagrosa A. Does sample length influence the shape of xylem embolism vulnerability curves? A test with the Cavitron spinning technique. PLANT, CELL & ENVIRONMENT 2010; 33:1543-1552. [PMID: 20444214 DOI: 10.1111/j.1365-3040.2010.02163.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The Cavitron spinning technique is used to construct xylem embolism vulnerability curves (VCs), but its reliability has been questioned for species with long vessels. This technique generates two types of VC: sigmoid 's'-shaped and exponential, levelling-off 'r'-shaped curves. We tested the hypothesis that 'r'-shaped VCs were anomalous and caused by the presence of vessels cut open during sample preparation. A Cavitron apparatus was used to construct VCs from samples of different lengths in species with contrasting vessel lengths. The results were compared with VCs obtained using other independent techniques. When vessel length exceeded sample length, VCs were 'r'-shaped and anomalous. Filling vessels cut open at both ends with air before measurement produced more typical 's'-shaped VCs. We also found that exposing segments of 11 woody species in a Cavitron at the pressure measured in planta before sampling considerably increased the degree of embolism above the native state level for species with long vessels. We concluded that open vessels were abnormally more vulnerable to cavitation than intact vessels. We recommend restricting this technique to species with short conduits. The relevance of our conclusions for other spinning techniques is discussed.
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Affiliation(s)
- Hervé Cochard
- INRA, UMR 547 PIAF, F-63100 Clermont-Ferrand, France.
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