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Liu M, Wang Y, Zhang H, Hao Y, Wu H, Shen H, Zhang P. Mechanisms of photoprotection in overwintering evergreen conifers: Sustained quenching of chlorophyll fluorescence. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2024; 210:108638. [PMID: 38653096 DOI: 10.1016/j.plaphy.2024.108638] [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: 11/12/2023] [Revised: 04/15/2024] [Accepted: 04/16/2024] [Indexed: 04/25/2024]
Abstract
Evergreen conifers growing in high-latitude regions must endure prolonged winters that are characterized by sub-zero temperatures combined with light, conditions that can cause significant photooxidative stress. Understanding overwintering mechanisms is crucial for addressing winter adversity in temperate forest ecosystems and enhancing the ability of conifers to adapt to climate change. This review synthesizes the current understanding of the photoprotective mechanisms that conifers employ to mitigate photooxidative stress, particularly non-photochemical "sustained quenching", the mechanism of which is hypothesized to be a recombination or deformation of the original mechanism employed by conifers in response to short-term low temperature and intense light stress in the past. Based on this hypothesis, scattered studies in this field are assembled and integrated into a complete mechanism of sustained quenching embedded in the adaptation process of plant physiology. It also reveals which parts of the whole system have been verified in conifers and which have only been verified in non-conifers, and proposes specific directions for future research. The functional implications of studies of non-coniferous plant species for the study of coniferous trees are also considered, as a wide range of plant responses lead to sustained quenching, even among different conifer species. In addition, the review highlights the challenges of measuring sustained quenching and discusses the application of ultrafast-time-resolved fluorescence and decay-associated spectra for the elucidation of photosynthetic principles.
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Affiliation(s)
- Mingyu Liu
- College of Forestry, Northeast Forestry University, Harbin, 150040, China.
| | - Yu Wang
- College of Life Sciences, Northeast Forestry University, Harbin, 150040, China.
| | - Huihui Zhang
- College of Life Sciences, Northeast Forestry University, Harbin, 150040, China.
| | - Yuanqin Hao
- College of Forestry, Northeast Forestry University, Harbin, 150040, China.
| | - Haibo Wu
- College of Forestry, Northeast Forestry University, Harbin, 150040, China; Key Laboratory of Sustainable Forest Ecosystem Management, Ministry of Education, Northeast Forestry University, Harbin, 150040, China; State Forestry and Grassland Administration Engineering Technology Research Center of Korean Pine, Harbin, 150040, China.
| | - Hailong Shen
- College of Forestry, Northeast Forestry University, Harbin, 150040, China; Key Laboratory of Sustainable Forest Ecosystem Management, Ministry of Education, Northeast Forestry University, Harbin, 150040, China; State Forestry and Grassland Administration Engineering Technology Research Center of Korean Pine, Harbin, 150040, China.
| | - Peng Zhang
- College of Forestry, Northeast Forestry University, Harbin, 150040, China; Key Laboratory of Sustainable Forest Ecosystem Management, Ministry of Education, Northeast Forestry University, Harbin, 150040, China; State Forestry and Grassland Administration Engineering Technology Research Center of Korean Pine, Harbin, 150040, China.
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Gamon JA, Wang R, Russo SE. Contrasting photoprotective responses of forest trees revealed using PRI light responses sampled with airborne imaging spectrometry. THE NEW PHYTOLOGIST 2023; 238:1318-1332. [PMID: 36658464 DOI: 10.1111/nph.18754] [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: 06/05/2022] [Accepted: 01/16/2023] [Indexed: 06/17/2023]
Abstract
The Photochemical Reflectance Index (PRI) provides an optical indicator of photosynthetic light-use efficiency, photoprotection, and stress in plants. Although PRI can be applied in remote sensing, its interpretation depends on irradiance, which is hard to obtain from satellite or airborne imagery. To quantify forest photoprotective responses remotely, we developed a framework for modeling and interpreting PRI-light responses of individual trees and species using airborne imaging spectrometry coupled with georeferenced forest inventory data from a temperate broad-leaved forest. We derived an irradiance proxy, used hierarchical modeling to analyze PRI-light responses, and developed a framework of physiological interpretations of model parameters as facultative and constitutive components of photoprotection. Photochemical Reflectance Index declined with illumination, and PRI-light relationships varied with landscape position and among tree crowns and species. More sun-exposed foliage had lower intercepts and slopes of the relationship, indicating greater constitutive, but less facultative, photoprotection. We show that tree photoprotective strategies can be quantified at multiple scales using airborne hyperspectral data in structurally complex forests. Our findings and approach have important implications for the remote sensing of forest stress by offering a new way to assess functional diversity through dynamic differences in photoprotection and photosynthetic downregulation and providing previsual indicators of forest stress.
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Affiliation(s)
- John A Gamon
- School of Natural Resources, University of Nebraska-Lincoln, Lincoln, NE, 68583-0961, USA
| | - Ran Wang
- School of Natural Resources, University of Nebraska-Lincoln, Lincoln, NE, 68583-0961, USA
| | - Sabrina E Russo
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE, 68588-0118, USA
- Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, NE, 68588-0660, USA
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