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Mercado-Reyes JA, Pereira TS, Manandhar A, Rimer IM, McAdam SAM. Extreme drought can deactivate ABA biosynthesis in embolism-resistant species. PLANT, CELL & ENVIRONMENT 2024; 47:497-510. [PMID: 37905689 DOI: 10.1111/pce.14754] [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: 03/25/2022] [Revised: 08/24/2023] [Accepted: 10/18/2023] [Indexed: 11/02/2023]
Abstract
The phytohormone abscisic acid (ABA) is synthesised by plants during drought to close stomata and regulate desiccation tolerance pathways. Conifers and some angiosperms with embolism-resistant xylem show a peaking-type (p-type) response in ABA levels, in which ABA levels increase early in drought then decrease as drought progresses, declining to pre-stressed levels. The mechanism behind this dynamic remains unknown. Here, we sought to characterise the mechanism driving p-type ABA dynamics in the conifer Callitris rhomboidea and the highly drought-resistant angiosperm Umbellularia californica. We measured leaf water potentials (Ψl ), stomatal conductance, ABA, conjugates and phaseic acid (PA) levels in potted plants during a prolonged but non-fatal drought. Both species displayed a p-type ABA dynamic during prolonged drought. In branches collected before and after the peak in endogenous ABA levels in planta, that were rehydrated overnight and then bench dried, ABA biosynthesis was deactivated beyond leaf turgor loss point. Considerable conversion of ABA to conjugates was found to occur during drought, but not catabolism to PA. The mechanism driving the decline in ABA levels in p-type species may be conserved across embolism-resistant seed plants and is mediated by sustained conjugation of ABA and the deactivation of ABA accumulation as Ψl becomes more negative than turgor loss.
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Affiliation(s)
- Joel A Mercado-Reyes
- Purdue Center for Plant Biology, Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, USA
| | - Talitha Soares Pereira
- Purdue Center for Plant Biology, Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, USA
| | - Anju Manandhar
- Purdue Center for Plant Biology, Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, USA
| | - Ian M Rimer
- Purdue Center for Plant Biology, Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, USA
| | - Scott A M McAdam
- Purdue Center for Plant Biology, Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, USA
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Lang W, Qian S, Chen X, Meng F. Spatiotemporal variation of cold requirements for leaf coloration and its environmental cues over the northern deciduous broadleaved forests. INTERNATIONAL JOURNAL OF BIOMETEOROLOGY 2023; 67:1409-1421. [PMID: 37479847 DOI: 10.1007/s00484-023-02508-1] [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: 01/20/2023] [Revised: 06/09/2023] [Accepted: 06/16/2023] [Indexed: 07/23/2023]
Abstract
Evaluating the interactions between cold requirements for leaf coloration and environmental cues is crucial for understanding the mechanisms of leaf senescence and accurately predicting autumn phenology. Based on remote sensing-derived and ground-observed leaf coloration dates for deciduous broadleaf forests during 1981-2014, we determined location-specific cold requirements for autumn leaf coloration and assessed their spatiotemporal changes. Then, we revealed the major environmental cues of cold requirements and their spatial differentiation. Results show that cold requirements have nonsignificant trends during the past decades at 57.9% of pixels. The interannual variation of cold requirements was mainly influenced by growing-season accumulated temperature (GDDgs) at 35.8% of pixels and accumulated growing season index (AGSI) at 23.2% of pixels, but less affected by leaf unfolding and low precipitation index (LPI). The increase in GDDgs or AGSI may decrease cold requirements, and vice versa. The spatial differentiations of the effects of GDDgs and AGSI depend highly on local summer temperature among climatic classifications with similar humidity conditions. Specifically, the effects of GDDgs on cold requirements concentrated in humid regions with warmer summers, while that of AGSI mainly occurred in humid and winter dry regions with cooler summers. Higher summer temperatures would strengthen the effects of GDDgs and reduce the effects of AGSI on cold requirements. These findings deepen the understanding of the influences of environmental factors on leaf senescence progress and suggest that the shifts of factors affecting cold requirements under global warming may enlarge the uncertainty in predicting autumn leaf coloration dates.
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Affiliation(s)
- Weiguang Lang
- College of Urban and Environmental Sciences, Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, Beijing, 100871, People's Republic of China
| | - Siwei Qian
- College of Urban and Environmental Sciences, Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, Beijing, 100871, People's Republic of China
| | - Xiaoqiu Chen
- College of Urban and Environmental Sciences, Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, Beijing, 100871, People's Republic of China.
| | - Fandong Meng
- College of Urban and Environmental Sciences, Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, Beijing, 100871, People's Republic of China
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Kane CN, McAdam SAM. Abscisic acid can augment, but is not essential for, autumnal leaf senescence. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:3255-3266. [PMID: 36882050 DOI: 10.1093/jxb/erad089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 03/04/2023] [Indexed: 05/21/2023]
Abstract
Senescence vividly marks the onset of the final stages of the life of a leaf, yet the triggers and drivers of this process are still not fully understood. The hormone abscisic acid (ABA) is an important regulator of leaf senescence in model herbs, but the function of this hormone has not been widely tested in deciduous trees. Here we investigate the importance of ABA as a driver of leaf senescence in winter deciduous trees. In four diverse species we tracked leaf gas exchange, water potential, chlorophyll content, and leaf ABA levels from the end of summer until leaves were abscised or died. We found that no change in ABA levels occurred at the onset of chlorophyll decline or throughout the duration of leaf senescence. To test whether ABA could enhance leaf senescence, we girdled branches to disrupt ABA export in the phloem. Girdling increased leaf ABA levels in two of the species, and this increase triggered an accelerated rate of chlorophyll decline in these species. We conclude that an increase in ABA level may augment leaf senescence in winter deciduous species but that it is not essential for this annual process.
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Affiliation(s)
- Cade N Kane
- 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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Abdalla M, Schweiger AH, Berauer BJ, McAdam SAM, Ahmed MA. Constant hydraulic supply and ABA dynamics facilitate the trade-offs in water and carbon. FRONTIERS IN PLANT SCIENCE 2023; 14:1140938. [PMID: 37008480 PMCID: PMC10064056 DOI: 10.3389/fpls.2023.1140938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Accepted: 03/03/2023] [Indexed: 06/19/2023]
Abstract
Carbon-water trade-offs in plants are adjusted through stomatal regulation. Stomatal opening enables carbon uptake and plant growth, whereas plants circumvent drought by closing stomata. The specific effects of leaf position and age on stomatal behavior remain largely unknown, especially under edaphic and atmospheric drought. Here, we compared stomatal conductance (gs ) across the canopy of tomato during soil drying. We measured gas exchange, foliage ABA level and soil-plant hydraulics under increasing vapor pressure deficit (VPD). Our results indicate a strong effect of canopy position on stomatal behavior, especially under hydrated soil conditions and relatively low VPD. In wet soil (soil water potential > -50 kPa), upper canopy leaves had the highest gs (0.727 ± 0.154 mol m-2 s-1) and assimilation rate (A; 23.4 ± 3.9 µmol m-2 s-1) compared to the leaves at a medium height of the canopy (gs : 0.159 ± 0.060 mol m2 s-1; A: 15.9 ± 3.8 µmol m-2 s-1). Under increasing VPD (from 1.8 to 2.6 kPa), gs , A and transpiration were initially impacted by leaf position rather than leaf age. However, under high VPD (2.6 kPa), age effect outweighed position effect. The soil-leaf hydraulic conductance was similar in all leaves. Foliage ABA levels increased with rising VPD in mature leaves at medium height (217.56 ± 85 ng g-1 FW) compared to upper canopy leaves (85.36 ± 34 ng g-1 FW). Under soil drought (< -50 kPa), stomata closed in all leaves resulting in no differences in gs across the canopy. We conclude that constant hydraulic supply and ABA dynamics facilitate preferential stomatal behavior and carbon-water trade-offs across the canopy. These findings are fundamental in understanding variations within the canopy, which helps in engineering future crops, especially in the face of climate change.
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Affiliation(s)
- Mohanned Abdalla
- Department of Land, Air and Water Resources, University of California Davis, Davis, CA, United States
- Chair of Soil Physics, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Bayreuth, Germany
- Department of Horticulture, Faculty of Agriculture, University of Khartoum, Khartoum North, Sudan
- Chair of Soil-Root Interactions, TUM School of Life Science, Technical University of Munich, Freising, Germany
| | - Andreas H. Schweiger
- Institute of Landscape and Plant Ecology, Department of Plant Ecology, University of Hohenheim, Stuttgart, Germany
| | - Bernd J. Berauer
- Institute of Landscape and Plant Ecology, Department of Plant Ecology, University of Hohenheim, Stuttgart, Germany
| | - Scott A. M. McAdam
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, United States
| | - Mutez Ali Ahmed
- Chair of Soil Physics, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Bayreuth, Germany
- Chair of Soil-Root Interactions, TUM School of Life Science, Technical University of Munich, Freising, Germany
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Schuldt B, Ruehr NK. Responses of European forests to global change-type droughts. PLANT BIOLOGY (STUTTGART, GERMANY) 2022; 24:1093-1097. [PMID: 36445187 DOI: 10.1111/plb.13484] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 11/08/2022] [Indexed: 06/16/2023]
Affiliation(s)
- B Schuldt
- Chair of Forest Botany, Institute of Forest Botany and Forest Zoology, Technical University of Dresden, Dresden, Germany
| | - N K Ruehr
- Karlsruhe Institute of Technology (KIT), Institute of Meteorology and Climate Research - Atmospheric Environmental Research (IMK-IFU), Garmisch-Partenkirchen, Germany
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Werner C. Extreme droughts and heatwaves endanger temperate forests. PLANT BIOLOGY (STUTTGART, GERMANY) 2022; 24:1091-1092. [PMID: 36445188 DOI: 10.1111/plb.13488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
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