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Harrison Day BL, Brodersen CR, Brodribb TJ. Weak link or strong foundation? Vulnerability of fine root networks and stems to xylem embolism. THE NEW PHYTOLOGIST 2024; 244:1288-1302. [PMID: 39267263 DOI: 10.1111/nph.20115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2024] [Accepted: 08/21/2024] [Indexed: 09/17/2024]
Abstract
Resolving the position of roots in the whole-plant hierarchy of drought-induced xylem embolism resistance is fundamental for predicting when species become isolated from soil water resources. Published research generally suggests that roots are the most vulnerable organ of the plant vascular system, although estimates vary significantly. However, our knowledge of root embolism excludes the fine roots (< 2 mm diameter) that form the bulk of total absorptive surface area of the root network for water and nutrient uptake. We measured fine root and stem xylem vulnerability in 10 vascular plant species from the major land plant clades (five angiosperms, three conifers, a fern and lycophyte), using standardised in situ methods (Optical Methods and MicroCT). Mean fine root embolism resistance across the network matched or exceeded stems in all study species. In six of these species (one fern, one lycophyte, three conifers and one angiosperm), fine roots were significantly more embolism resistant than stems. No clear relationship was found between root xylem conduit diameter and vulnerability. These results provide insight into the resistance of the plant hydraulic pathway at the site of water and nutrient uptake, and challenge the long-standing assumption that fine roots are more vulnerable than stems.
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Affiliation(s)
- Beatrice L Harrison Day
- School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, TAS, 7001, Australia
- School of the Environment, Yale University, New Haven, CT, 06520, USA
| | - Craig R Brodersen
- School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, TAS, 7001, Australia
- School of the Environment, Yale University, New Haven, CT, 06520, USA
| | - Timothy J Brodribb
- School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, TAS, 7001, Australia
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2
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Zhao N, Zhao J, Li S, Li B, Lv J, Gao X, Xu X, Lu S. The Response of Endogenous ABA and Soluble Sugars of Platycladus orientalis to Drought and Post-Drought Rehydration. BIOLOGY 2024; 13:194. [PMID: 38534463 DOI: 10.3390/biology13030194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2024] [Revised: 03/13/2024] [Accepted: 03/15/2024] [Indexed: 03/28/2024]
Abstract
To uncover the internal mechanisms of various drought stress intensities affecting the soluble sugar content in organs and its regulation by endogenous abscisic acid (ABA), we selected the saplings of Platycladus orientalis, a typical tree species in the Beijing area, as our research subject. We investigated the correlation between tree soluble sugars and endogenous ABA in the organs (comprised of leaf, branch, stem, coarse root, and fine root) under two water treatments. One water treatment was defined as T1, which stopped watering until the potted soil volumetric water content (SWC) reached the wilting coefficient and then rewatered the sapling. The other water treatment, named T2, replenished 95% of the total water loss of one potted sapling every day and irrigated the above-mentioned sapling after its SWC reached the wilt coefficients. The results revealed that (1) the photosynthetic physiological parameters of P. orientalis were significantly reduced (p < 0.05) under fast and slow drought processes. The photosynthetic physiological parameters of P. orientalis in the fast drought-rehydration treatment group recovered faster relative to the slow drought-rehydration treatment group. (2) The fast and slow drought treatments significantly (p < 0.05) increased the ABA and soluble sugar contents in all organs. The roots of the P. orientalis exhibited higher sensitivity in ABA and soluble sugar content to changes in soil moisture dynamics compared to other organs. (3) ABA and soluble sugar content of P. orientalis showed a significant positive correlation (p < 0.05) under fast and slow drought conditions. During the rehydration stage, the two were significantly correlated in the T2 treatment (p < 0.05). In summary, soil drought rhythms significantly affected the photosynthetic parameters, organ ABA, and soluble sugar content of P. orientalis. This study elucidates the adaptive mechanisms of P. orientalis plants to drought and rehydration under the above-mentioned two water drought treatments, offering theoretical insights for selecting and cultivating drought-tolerant tree species.
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Affiliation(s)
- Na Zhao
- Institute of Forestry and Pomology, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100093, China
- Beijing Yanshan Forest Ecosystem Research Station, National Forest and Grassland Administration, Beijing 100093, China
| | - Jiahui Zhao
- Institute of Forestry and Pomology, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100093, China
- Beijing Yanshan Forest Ecosystem Research Station, National Forest and Grassland Administration, Beijing 100093, China
- College of Forestry, Shenyang Agricultural University, Shenyang 110866, China
| | - Shaoning Li
- Institute of Forestry and Pomology, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100093, China
- Beijing Yanshan Forest Ecosystem Research Station, National Forest and Grassland Administration, Beijing 100093, China
- College of Forestry, Shenyang Agricultural University, Shenyang 110866, China
| | - Bin Li
- Institute of Forestry and Pomology, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100093, China
- Beijing Yanshan Forest Ecosystem Research Station, National Forest and Grassland Administration, Beijing 100093, China
| | - Jiankui Lv
- Institute of Forestry and Pomology, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100093, China
- Beijing Yanshan Forest Ecosystem Research Station, National Forest and Grassland Administration, Beijing 100093, China
- College of Forestry, Shenyang Agricultural University, Shenyang 110866, China
| | - Xin Gao
- Institute of Forestry and Pomology, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100093, China
- Beijing Yanshan Forest Ecosystem Research Station, National Forest and Grassland Administration, Beijing 100093, China
- College of Forestry, Shenyang Agricultural University, Shenyang 110866, China
| | - Xiaotian Xu
- Institute of Forestry and Pomology, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100093, China
- Beijing Yanshan Forest Ecosystem Research Station, National Forest and Grassland Administration, Beijing 100093, China
| | - Shaowei Lu
- Institute of Forestry and Pomology, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100093, China
- Beijing Yanshan Forest Ecosystem Research Station, National Forest and Grassland Administration, Beijing 100093, China
- College of Forestry, Shenyang Agricultural University, Shenyang 110866, China
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Quintanilla LG, Aranda I, Clemente-Moreno MJ, Pons-Perpinyà J, Gago J. Ecophysiological Differentiation among Two Resurrection Ferns and Their Allopolyploid Derivative. PLANTS (BASEL, SWITZERLAND) 2023; 12:1529. [PMID: 37050155 PMCID: PMC10096763 DOI: 10.3390/plants12071529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 03/27/2023] [Accepted: 03/30/2023] [Indexed: 06/19/2023]
Abstract
Theoretically, the coexistence of diploids and related polyploids is constrained by reproductive and competitive mechanisms. Although niche differentiation can explain the commonly observed co-occurrence of cytotypes, the underlying ecophysiological differentiation among cytotypes has hardly been studied. We compared the leaf functional traits of the allotetraploid resurrection fern Oeosporangium tinaei (HHPP) and its diploid parents, O. hispanicum (HH) and O. pteridioides (PP), coexisting in the same location. Our experimental results showed that all three species can recover physiological status after severe leaf dehydration, which confirms their 'resurrection' ability. However, compared with PP, HH had much higher investment per unit area of light-capturing surface, lower carbon assimilation rate per unit mass for the same midday water potential, higher non-enzymatic antioxidant capacity, higher carbon content, and lower contents of nitrogen, phosphorus, and other macronutrients. These traits allow HH to live in microhabitats with less availability of water and nutrients (rock crevices) and to have a greater capacity for resurrection. The higher assimilation capacity and lower antioxidant capacity of PP explain its more humid and nutrient-rich microhabitats (shallow soils). HHPP traits were mostly intermediate between those of HH and PP, and they allow the allotetraploid to occupy the free niche space left by the diploids.
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Affiliation(s)
- Luis G. Quintanilla
- School of Environmental Sciences and Technology (ESCET), University Rey Juan Carlos, 28922 Móstoles, Spain
| | - Ismael Aranda
- National Institute for Agricultural and Food Research and Technology (INIA), Spanish National Research Council, 28040 Madrid, Spain
| | - María José Clemente-Moreno
- Agro-Environmental and Water Economics Institute (INAGEA), University of the Balearic Islands, 07122 Palma de Mallorca, Spain
| | - Joan Pons-Perpinyà
- Agro-Environmental and Water Economics Institute (INAGEA), University of the Balearic Islands, 07122 Palma de Mallorca, Spain
| | - Jorge Gago
- Agro-Environmental and Water Economics Institute (INAGEA), University of the Balearic Islands, 07122 Palma de Mallorca, Spain
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Pittermann J, Baer A, Campany C, Jansen S, Holmlund H, Schuettpelz E, Mehltreter K, Watkins JE. A reduced role for water transport during the Cenozoic evolution of epiphytic Eupolypod ferns. THE NEW PHYTOLOGIST 2023; 237:1745-1758. [PMID: 36484140 DOI: 10.1111/nph.18667] [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: 07/01/2022] [Accepted: 11/15/2022] [Indexed: 06/17/2023]
Abstract
The Cretaceous-Cenozoic expansion of tropical forests created canopy space that was subsequently occupied by diverse epiphytic communities including Eupolypod ferns. Eupolypods proliferated in this more stressful niche, where lower competition enabled the adaptive radiation of thousands of species. Here, we examine whether xylem traits helped shape the Cenozoic radiation of Eupolypod ferns. We characterized the petiole xylem anatomy of 39 species belonging to the Eupolypod I and Eupolypod II clades occupying the epiphytic, hemiepiphytic, and terrestrial niche, and we assessed vulnerability to embolism in a subset of species. The transition to the canopy was associated with reduced xylem content and smaller tracheid diameters, but no differences were found in species vulnerability to embolism and pit membrane thickness. Phylogenetic analyses support selection for traits associated with reduced water transport in Eupolypod 1 species. We posit that in Eupolypod epiphytes, selection favored water retention via thicker leaves and lower stomatal density over higher rates of water transport. Consequently, lower leaf water loss was coupled with smaller quantities of xylem and narrower tracheid diameters. Traits associated with water conservation were evident in terrestrial Eupolypod 1 ferns and may have predisposed this clade toward radiation in the canopy.
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Affiliation(s)
- Jarmila Pittermann
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA, 95060, USA
| | - Alex Baer
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA, 95060, USA
| | - Courtney Campany
- Department of Biology, Shepherd University, Shepherdstown, WV, 25443, USA
| | - Steven Jansen
- Institute for Systematic Botany and Ecology, University of Ulm, Ulm, 89081, Germany
| | - Helen Holmlund
- Natural Science Division, Pepperdine University, Malibu, CA, 90263, USA
| | - Eric Schuettpelz
- Department of Botany, National Museum of Natural History, Smithsonian Institution, Washington, DC, 20560, USA
| | - Klaus Mehltreter
- Red de Ecologia Funcíonal, Instituto de Ecología A.C, Xalapa, Veracruz, 91073, Mexico
| | - James E Watkins
- Department of Biology, Colgate University, Hamilton, NY, 13346, USA
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Pittermann J, Baer A, Sang Y. Primary tissues may affect estimates of cavitation resistance in ferns. THE NEW PHYTOLOGIST 2021; 231:285-296. [PMID: 33786827 DOI: 10.1111/nph.17374] [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: 05/31/2020] [Accepted: 03/11/2021] [Indexed: 06/12/2023]
Abstract
Different methods of measuring cavitation resistance in fern petioles lead to variable results, particularly with respect to the P50 metric. We hypothesised that the fern dictyostele structure affects air entry into the xylem, and therefore impacts the shape of the vulnerability curve. Our study examined this variation by comparing vulnerability curves constructed on petioles collected from evergreen and deciduous ferns in the field, with curves generated using the standard centrifuge, air-injection and bench-top dehydration methods. Additional experiments complemented the vulnerability curves to better understand how anatomy shapes estimates of cavitation resistance. Centrifugation and radial air injection generated acceptable vulnerability curves for the deciduous species, but overestimated drought resistance in the two evergreen ferns. In these hardy plants, axial air injection and bench-top dehydration produced results that most closely aligned with observations in nature. Additional experiments revealed that the dictyostele anatomy impedes air entry into the xylem during spinning and radial air injection. Each method produced acceptable vulnerability curves, depending on the species being tested. Therefore, we stress the importance of validating the curves with in situ measures of water potential and, if possible, hydraulic data to generate realistic results with any of the methods currently available.
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Affiliation(s)
- Jarmila Pittermann
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA, 95060, USA
| | - Alex Baer
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA, 95060, USA
| | - Ying Sang
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA, 95060, USA
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Campany CE, Pittermann J, Baer A, Holmlund H, Schuettpelz E, Mehltreter K, Watkins JE. Leaf water relations in epiphytic ferns are driven by drought avoidance rather than tolerance mechanisms. PLANT, CELL & ENVIRONMENT 2021; 44:1741-1755. [PMID: 33665827 DOI: 10.1111/pce.14042] [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: 08/07/2020] [Revised: 02/22/2021] [Accepted: 02/23/2021] [Indexed: 06/12/2023]
Abstract
Opportunistic diversification has allowed ferns to radiate into epiphytic niches in angiosperm dominated landscapes. However, our understanding of how ecophysiological function allowed establishment in the canopy and the potential transitionary role of the hemi-epiphytic life form remain unclear. Here, we surveyed 39 fern species in Costa Rican tropical forests to explore epiphytic trait divergence in a phylogenetic context. We examined leaf responses to water deficits in terrestrial, hemi-epiphytic and epiphytic ferns and related these findings to functional traits that regulate leaf water status. Epiphytic ferns had reduced xylem area (-63%), shorter stipe lengths (-56%), thicker laminae (+41%) and reduced stomatal density (-46%) compared to terrestrial ferns. Epiphytic ferns exhibited similar turgor loss points, higher osmotic potential at saturation and lower tissue capacitance after turgor loss than terrestrial ferns. Overall, hemi-epiphytic ferns exhibited traits that share characteristics of both terrestrial and epiphytic species. Our findings clearly demonstrate the prevalence of water conservatism in both epiphytic and hemi-epiphytic ferns, via selection for anatomical and structural traits that avoid leaf water stress. Even with likely evolutionarily constrained physiological function, adaptations for drought avoidance have allowed epiphytic ferns to successfully endure the stresses of the canopy habitat.
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Affiliation(s)
- Courtney E Campany
- Department of Biology, Shepherd University, Shepherdstown, West Virginia, USA
- Department of Biology, Colgate University, Hamilton, New York, USA
| | - Jarmila Pittermann
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, California, USA
| | - Alex Baer
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, California, USA
| | - Helen Holmlund
- Natural Science Division, Pepperdine University, Malibu, California, USA
| | - Eric Schuettpelz
- Department of Botany, National Museum of Natural History, Smithsonian Institution, Washington, District of Columbia, USA
| | - Klaus Mehltreter
- Red de Ecología Funcional, Instituto de Ecología A.C., Xalapa, Mexico
- Institute for Systematic Botany and Ecology, University of Ulm, Ulm, Germany
| | - James E Watkins
- Department of Biology, Colgate University, Hamilton, New York, USA
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Yao G, Nie Z, Turner NC, Li F, Gao T, Fang X, Scoffoni C. Combined high leaf hydraulic safety and efficiency provides drought tolerance in Caragana species adapted to low mean annual precipitation. THE NEW PHYTOLOGIST 2021; 229:230-244. [PMID: 32749703 PMCID: PMC7754512 DOI: 10.1111/nph.16845] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Accepted: 07/22/2020] [Indexed: 05/04/2023]
Abstract
Clarifying the coordination of leaf hydraulic traits with gas exchange across closely-related species adapted to varying rainfall can provide insights into plant habitat distribution and drought adaptation. The leaf hydraulic conductance (Kleaf ), stomatal conductance (gs ), net assimilation (A), vein embolism and abscisic acid (ABA) concentration during dehydration were quantified, as well as pressure-volume curve traits and vein anatomy in 10 Caragana species adapted to a range of mean annual precipitation (MAP) conditions and growing in a common garden. We found a positive correlation between Ψleaf at 50% loss of Kleaf (Kleaf P50 ) and maximum Kleaf (Kleaf-max ) across species. Species from low-MAP environments exhibited more negative Kleaf P50 and turgor loss point, and higher Kleaf-max and leaf-specific capacity at full turgor, along with higher vein density and midrib xylem per leaf area, and a higher ratio of Kleaf-max : maximum gs . Tighter stomatal control mediated by higher ABA accumulation during dehydration in these species resulted in an increase in hydraulic safety and intrinsic water use efficiency (WUEi ) during drought. Our results suggest that high hydraulic safety and efficiency combined with greater stomatal sensitivity triggered by ABA production and leading to greater WUEi provides drought tolerance in Caragana species adapted to low-MAP environments.
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Affiliation(s)
- Guang‐Qian Yao
- State Key Laboratory of Grassland Agro‐ecosystemsSchool of Life SciencesLanzhou UniversityLanzhou730000China
| | - Zheng‐Fei Nie
- State Key Laboratory of Grassland Agro‐ecosystemsSchool of Life SciencesLanzhou UniversityLanzhou730000China
| | - Neil C. Turner
- State Key Laboratory of Grassland Agro‐ecosystemsSchool of Life SciencesLanzhou UniversityLanzhou730000China
- The UWA Institute of Agriculture and UWA School of Agriculture and EnvironmentThe University of Western AustraliaM082, 35 Stirling HighwayCrawleyWA6009Australia
| | - Feng‐Min Li
- State Key Laboratory of Grassland Agro‐ecosystemsSchool of Life SciencesLanzhou UniversityLanzhou730000China
| | - Tian‐Peng Gao
- The Engineering Research Center of Mining Pollution Treatment and Ecological Restoration of Gansu ProvinceLanzhou City UniversityLanzhou730070China
| | - Xiang‐Wen Fang
- State Key Laboratory of Grassland Agro‐ecosystemsSchool of Life SciencesLanzhou UniversityLanzhou730000China
| | - Christine Scoffoni
- Department of Biological SciencesCalifornia State University Los Angeles5151 State University DriveLos AngelesCA90032USA
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Li Q, Wang N, Liu X, Liu S, Wang H, Zhang W, Wang R, Du N. Growth and physiological responses to successional water deficit and recovery in four warm-temperate woody species. PHYSIOLOGIA PLANTARUM 2019; 167:645-660. [PMID: 30637759 DOI: 10.1111/ppl.12922] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 12/20/2018] [Accepted: 01/08/2019] [Indexed: 05/19/2023]
Abstract
Plant responses to drought and their subsequent rehydration can provide evidence for forest dynamics within the context of climate change. In this study, the seedlings of two native species (Vitex negundo var. heterophylla, Quercus acutissima) and two exotic species (Robinia pseudoacacia, Amorpha fruticosa) to China were selected in a greenhouse experiment. The gas exchange, stem hydraulic parameters, plant osmoprotectant contents and antioxidant activities of the seedlings that were subjected to sustained drought and rehydration (test group) as well as those of well-irrigated seedlings (control group) were measured. The two native species exhibited a greater degree of isohydry with drought because they limited the stomatal opening timely from the onset of the drought. However, the two exotic species showed a more 'water spender'-like strategy with R. pseudoacacia showing anisohydric responses and A. fruticosa showing isohydrodynamic responses to drought. Severe drought significantly decreased the leaf gas exchange rates and hydraulic properties, whereas the instantaneous water use efficiency and osmoprotectant contents increased markedly. Most of the physiological parameters recovered rapidly after mild drought rehydration, but the water potential and/or supply of nonstructural carbohydrates did not recover after severe drought rehydration. The results demonstrate that the xylem hydraulic conductivity and shoot water potential jointly play a crucial role in the drought recovery of woody plants. In brief, the native species may play a dominant role in the future in warm-temperate forests because they employ a better balance between carbon gain and water loss than the alien species under extreme drought conditions.
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Affiliation(s)
- Qiang Li
- Institute of Ecology and Biodiversity, School of Life Sciences, Shandong University, Qingdao, 266237, China
- Shandong Provincial Engineering and Technology Research Center for Vegetation Ecology, Shandong University, Qingdao, 266237, China
| | - Ning Wang
- Institute of Ecology and Biodiversity, School of Life Sciences, Shandong University, Qingdao, 266237, China
- Shandong Provincial Engineering and Technology Research Center for Vegetation Ecology, Shandong University, Qingdao, 266237, China
| | - Xiao Liu
- Institute of Ecology and Biodiversity, School of Life Sciences, Shandong University, Qingdao, 266237, China
- Shandong Provincial Engineering and Technology Research Center for Vegetation Ecology, Shandong University, Qingdao, 266237, China
| | - Shuna Liu
- Institute of Ecology and Biodiversity, School of Life Sciences, Shandong University, Qingdao, 266237, China
- Shandong Provincial Engineering and Technology Research Center for Vegetation Ecology, Shandong University, Qingdao, 266237, China
| | - Hui Wang
- Institute of Ecology and Biodiversity, School of Life Sciences, Shandong University, Qingdao, 266237, China
- Shandong Provincial Engineering and Technology Research Center for Vegetation Ecology, Shandong University, Qingdao, 266237, China
| | - Wenxin Zhang
- Institute of Ecology and Biodiversity, School of Life Sciences, Shandong University, Qingdao, 266237, China
- Shandong Provincial Engineering and Technology Research Center for Vegetation Ecology, Shandong University, Qingdao, 266237, China
| | - Renqing Wang
- Institute of Ecology and Biodiversity, School of Life Sciences, Shandong University, Qingdao, 266237, China
- Shandong Provincial Engineering and Technology Research Center for Vegetation Ecology, Shandong University, Qingdao, 266237, China
| | - Ning Du
- Institute of Ecology and Biodiversity, School of Life Sciences, Shandong University, Qingdao, 266237, China
- Shandong Provincial Engineering and Technology Research Center for Vegetation Ecology, Shandong University, Qingdao, 266237, China
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Pittermann J, Cowan J, Kaufman N, Baer A, Zhang E, Kuty D. The water relations and xylem attributes of albino redwood shoots (Sequioa sempervirens (D. Don.) Endl.). PLoS One 2018; 13:e0191836. [PMID: 29590113 PMCID: PMC5873723 DOI: 10.1371/journal.pone.0191836] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 01/11/2018] [Indexed: 11/18/2022] Open
Abstract
Plants that lack chlorophyll are rare and typically restricted to holoparasites that obtain their carbon, water and mineral resources from a host plant. Although not parasites in the traditional sense, albino foliage, such as the sprouts that sometimes develop from redwood tree trunks, are comparable in function. They occur sporadically, and can reach the size of shrubs and in rare cases, trees. Albino redwoods are interesting because in addition to their reduced carbon resources, the absence of chloroplasts may impede proper stomatal function, and both aspects may have upstream consequences on water transport and xylem quality. We examined the water relations, water transport and xylem anatomical attributes of albino redwoods and show that similar to achlorophyllous and parasitic plants, albino redwoods have notably higher stomatal conductance than green sprouts. Given that stem xylem tracheid size as well as water transport efficiency are nearly equivalent in both albino and green individuals, we attribute the increased leaf water loss in albino sprouts to lower leaf to xylem area ratios, which favour improved hydration relative to green sprouts. The stems of albino redwoods were more vulnerable to drought-induced embolism than green stems, and this was consistent with the albino's weaker tracheids, as characterized by wall thickness to lumen diameter measures. Our results are both complementary and consistent with previous research on achlorophyllous plants, and suggest that the loss of stomatal control and photosynthetic capacity results in substantial vascular and anatomical adjustments.
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Affiliation(s)
- Jarmila Pittermann
- Department of Ecology and Evolutionary Biology, University of California, United States of America
| | - Joshua Cowan
- Department of Ecology and Evolutionary Biology, University of California, United States of America
| | - Nathan Kaufman
- Urban Adamah, Berkeley, California, United States of America
| | - Alex Baer
- Department of Biology, California State University, California, United States of America
| | - Elaine Zhang
- College of Arts and Science, University of San Francisco, San Francisco, California, United States of America
| | - David Kuty
- Henry Cowell Redwoods State Park, Felton, California, United States of America
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10
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Brodribb TJ, McAdam SA, Carins Murphy MR. Xylem and stomata, coordinated through time and space. PLANT, CELL & ENVIRONMENT 2017; 40:872-880. [PMID: 27531223 DOI: 10.1111/pce.12817] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 08/07/2016] [Accepted: 08/10/2016] [Indexed: 05/18/2023]
Abstract
Land plants exhibit a degree of homeostasis in leaf water content to protect against damage to photosynthetic and xylem tissues, and to maintain an efficient allocation of resources. This is achieved by a strong coordination between the systems regulating water delivery (xylem) and water loss (stomata). This review discusses evolution in xylem and stomatal function, specifically focussing on the interactions between them.
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Affiliation(s)
- Timothy J Brodribb
- School of Biological Sciences, University of Tasmania, Hobart, Tasmania, 7001, Australia
| | - Scott Am McAdam
- School of Biological Sciences, University of Tasmania, Hobart, Tasmania, 7001, Australia
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Hacke UG, Spicer R, Schreiber SG, Plavcová L. An ecophysiological and developmental perspective on variation in vessel diameter. PLANT, CELL & ENVIRONMENT 2017; 40:831-845. [PMID: 27304704 DOI: 10.1111/pce.12777] [Citation(s) in RCA: 129] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 05/27/2016] [Accepted: 05/31/2016] [Indexed: 05/05/2023]
Abstract
Variation in xylem vessel diameter is one of the most important parameters when evaluating plant water relations. This review provides a synthesis of the ecophysiological implications of variation in lumen diameter together with a summary of our current understanding of vessel development and its endogenous regulation. We analyzed inter-specific variation of the mean hydraulic vessel diameter (Dv ) across biomes, intra-specific variation of Dv under natural and controlled conditions, and intra-plant variation. We found that the Dv measured in young branches tends to stay below 30 µm in regions experiencing winter frost, whereas it is highly variable in the tropical rainforest. Within a plant, the widest vessels are often found in the trunk and in large roots; smaller diameters have been reported for leaves and small lateral roots. Dv varies in response to environmental factors and is not only a function of plant size. Despite the wealth of data on vessel diameter variation, the regulation of diameter is poorly understood. Polar auxin transport through the vascular cambium is a key regulator linking foliar and xylem development. Limited evidence suggests that auxin transport is also a determinant of vessel diameter. The role of auxin in cell expansion and in establishing longitudinal continuity during secondary growth deserve further study.
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Affiliation(s)
- Uwe G Hacke
- University of Alberta, Department of Renewable Resources, Edmonton, AB T6G 2E3, Canada
| | - Rachel Spicer
- Connecticut College, Department of Botany, New London, CT 06320, USA
| | - Stefan G Schreiber
- University of Alberta, Department of Renewable Resources, Edmonton, AB T6G 2E3, Canada
| | - Lenka Plavcová
- University of Hradec Králové, Department of Biology, Rokitanského 62, Hradec Králové, 500 03, Czech Republic
- Charles University, Department of Experimental Plant Biology, Viničná 5, Prague, 128 44, Czech Republic
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Burns EE, Pittermann J, Rico C. Evergreen and Deciduous Ferns of the Coast Redwood Forest. ACTA ACUST UNITED AC 2016. [DOI: 10.3120/0024-9637-63.4.329] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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