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Matos IS, McDonough S, Johnson BC, Kalantar D, Rohde J, Sahu R, Wang J, Fontao A, To J, Carlos S, Garcia L, Boakye M, Forbes H, Blonder BW. Negative allometry of leaf xylem conduit diameter and double-wall thickness: implications for implosion safety. THE NEW PHYTOLOGIST 2024; 242:2464-2478. [PMID: 38641796 DOI: 10.1111/nph.19771] [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: 12/11/2023] [Accepted: 03/25/2024] [Indexed: 04/21/2024]
Abstract
Xylem conduits have lignified walls to resist crushing pressures. The thicker the double-wall (T) relative to its diameter (D), the greater the implosion safety. Having safer conduits may incur higher costs and reduced flow, while having less resistant xylem may lead to catastrophic collapse under drought. Although recent studies have shown that conduit implosion commonly occurs in leaves, little is known about how leaf xylem scales T vs D to trade off safety, flow efficiency, mechanical support, and cost. We measured T and D in > 7000 conduits of 122 species to investigate how T vs D scaling varies across clades, habitats, growth forms, leaf, and vein sizes. As conduits become wider, their double-cell walls become proportionally thinner, resulting in a negative allometry between T and D. That is, narrower conduits, which are usually subjected to more negative pressures, are proportionally safer than wider ones. Higher implosion safety (i.e. higher T/D ratios) was found in asterids, arid habitats, shrubs, small leaves, and minor veins. Despite the strong allometry, implosion safety does not clearly trade off with other measured leaf functions, suggesting that implosion safety at whole-leaf level cannot be easily predicted solely by individual conduits' anatomy.
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Affiliation(s)
- Ilaine Silveira Matos
- Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA, 94720, USA
- School of Biological Sciences, The University of Adelaide, Adelaide, SA, 5005, Australia
| | - Samantha McDonough
- Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA, 94720, USA
| | - Breanna Carrillo Johnson
- Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA, 94720, USA
| | - Diana Kalantar
- Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA, 94720, USA
| | - James Rohde
- Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA, 94720, USA
| | - Roshni Sahu
- Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA, 94720, USA
| | - Joyce Wang
- Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA, 94720, USA
| | - Adrian Fontao
- Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA, 94720, USA
| | - Jason To
- Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA, 94720, USA
| | - Sonoma Carlos
- Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA, 94720, USA
| | - Lisa Garcia
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA
| | - Mickey Boakye
- Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA, 94720, USA
| | - Holly Forbes
- University of California Botanical Garden, Berkeley, CA, 94720, USA
| | - Benjamin Wong Blonder
- Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA, 94720, USA
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Li J, Ren J, Lei X, Fan W, Tang L, Zhang Q, Bao Z, Zhou W, Bai J, Zhang Y, Gong C. CsREV-CsTCP4-CsVND7 module shapes xylem patterns differentially between stem and leaf to enhance tea plant tolerance to drought. Cell Rep 2024; 43:113987. [PMID: 38517888 DOI: 10.1016/j.celrep.2024.113987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 01/22/2024] [Accepted: 03/07/2024] [Indexed: 03/24/2024] Open
Abstract
Cultivating drought-tolerant tea varieties enhances both yield and quality of tea plants in northern China. However, the mechanisms underlying their drought tolerance remain largely unknown. Here we identified a key regulator called CsREV, which differentially regulates xylem patterns between leaves and stems, thereby conferring drought tolerance in tea plants. When drought occurs, upregulation of CsREV activates the CsVND7a-dependent xylem vessel differentiation. However, when drought persists, the vessel differentiation is hindered as CsVND7a is downregulated by CsTCP4a. This, combined with the CsREV-promoted secondary-cell-wall thickness of xylem vessel, leads to the enhanced curling of leaves, a characteristic closely associated with plant drought tolerance. Notably, this inhibitory effect of CsTCP4a on CsVND7a expression is absent in stems, allowing stem xylem vessels to continuously differentiate. Overall, the CsREV-CsTCP4-CsVND7 module is differentially utilized to shape the xylem patterns in leaves and stems, potentially balancing water transportation and utilization to improve tea plant drought tolerance.
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Affiliation(s)
- Jiayang Li
- College of Horticulture, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Jiejie Ren
- College of Horticulture, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Xingyu Lei
- College of Horticulture, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Wenmin Fan
- College of Horticulture, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Lei Tang
- College of Horticulture, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Qiqi Zhang
- College of Horticulture, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Zhulatai Bao
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Wenfei Zhou
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Juan Bai
- College of Horticulture, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Yuzhou Zhang
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Chunmei Gong
- College of Horticulture, Northwest A&F University, Yangling, Shaanxi 712100, China.
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Binstock BR, Manandhar A, McAdam SAM. Characterizing the breakpoint of stomatal response to vapor pressure deficit in an angiosperm. PLANT PHYSIOLOGY 2024; 194:732-740. [PMID: 37850913 DOI: 10.1093/plphys/kiad560] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 09/21/2023] [Accepted: 10/05/2023] [Indexed: 10/19/2023]
Abstract
Vapor pressure difference between the leaf and atmosphere (VPD) is the most important regulator of daytime transpiration, yet the mechanism driving stomatal responses to an increase in VPD in angiosperms remains unresolved. Here, we sought to characterize the mechanism driving stomatal closure at high VPD in an angiosperm species, particularly testing whether abscisic acid (ABA) biosynthesis could explain the observation of a trigger point for stomatal sensitivity to an increase in VPD. We tracked leaf gas exchange and modeled leaf water potential (Ψl) in leaves exposed to a range of step-increases in VPD in the herbaceous species Senecio minimus Poir. (Asteraceae). We found that mild increases in VPD in this species did not induce stomatal closure because modeled Ψl did not decline below a threshold close to turgor loss point (Ψtlp), but when leaves were exposed to a large increase in VPD, stomata closed as modeled Ψl declined below Ψtlp. Leaf ABA levels were higher in leaves exposed to a step-increase in VPD that caused Ψl to transiently decline below Ψtlp and in which stomata closed compared with leaves in which stomata did not close. We conclude that the stomata of S. minimus are insensitive to VPD until Ψl declines to a threshold that triggers the biosynthesis of ABA and that this mechanism might be common to angiosperms.
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Affiliation(s)
- Benjamin R Binstock
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907, USA
| | - Anju Manandhar
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907, USA
| | - Scott A M McAdam
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907, USA
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Scoffoni C, Albuquerque C, Buckley TN, Sack L. The dynamic multi-functionality of leaf water transport outside the xylem. THE NEW PHYTOLOGIST 2023; 239:2099-2107. [PMID: 37386735 DOI: 10.1111/nph.19069] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2022] [Accepted: 05/12/2023] [Indexed: 07/01/2023]
Abstract
A surge of papers have reported low leaf vulnerability to xylem embolism during drought. Here, we focus on the less studied, and more sensitive, outside-xylem leaf hydraulic responses to multiple internal and external conditions. Studies of 34 species have resolved substantial vulnerability to dehydration of the outside-xylem pathways, and studies of leaf hydraulic responses to light also implicate dynamic outside-xylem responses. Detailed experiments suggest these dynamic responses arise at least in part from strong control of radial water movement across the vein bundle sheath. While leaf xylem vulnerability may influence leaf and plant survival during extreme drought, outside-xylem dynamic responses are important for the control and resilience of water transport and leaf water status for gas exchange and growth.
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Affiliation(s)
- Christine Scoffoni
- Department of Biological Sciences, California State University Los Angeles, 5151 State University Dr., Los Angeles, CA, 90032, USA
| | - Caetano Albuquerque
- Department of Biological Sciences, California State University Los Angeles, 5151 State University Dr., Los Angeles, CA, 90032, USA
| | - Thomas N Buckley
- Department of Plant Sciences, University of California, Davis, 1 Shields Ave, Davis, CA, 95616, USA
| | - Lawren Sack
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, 612 Charles E. Young Dr., Los Angeles, CA, 90095, USA
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