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Deng Q, Wang H, Qiu Y, Wang D, Xia Y, Zhang Y, Pei M, Zhao Y, Xu X, Zhang H. The Multifaceted Impact of Karrikin Signaling in Plants. Int J Mol Sci 2025; 26:2775. [PMID: 40141418 PMCID: PMC11943027 DOI: 10.3390/ijms26062775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2024] [Revised: 03/04/2025] [Accepted: 03/06/2025] [Indexed: 03/28/2025] Open
Abstract
Karrikins (KARs), produced during wildfires, are bioactive compounds that stimulate seed germination in fire-prone ecosystems and influence broader plant-environment interactions. These compounds act through the α/β hydrolase receptor KARRIKIN INSENSITIVE2 (KAI2), which perceives KARs as analogs of the hypothesized phytohormone KAI2 ligand (KL). KAR signaling shares molecular parallels with strigolactones (SLs), another class of butenolide plant hormones, and regulates diverse processes such as seedling development, root architecture, photomorphogenesis, and stress responses. Despite its multifaceted roles, the mechanistic basis of KAR-mediated regulation remains poorly understood. This review synthesizes insights into KAR signaling mechanisms, emphasizing recent advances in signal transduction pathways and functional studies. It also addresses key unresolved questions, including the identity of endogenous KL and the crosstalk between KARs and other hormonal networks. By elucidating these mechanisms, KAR-based strategies hold promises for enhancing crop resilience and sustainability, offering novel avenues for agricultural innovation in changing environments.
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Affiliation(s)
- Qilin Deng
- State Key Laboratory of Vegetable Biobreeding, Beijing Vegetable Research Center, Beijing Academy of Agriculture and Forestry Science, Beijing 100097, China; (Q.D.); (H.W.); (Y.Q.); (D.W.); (Y.X.); (Y.Z.); (M.P.); (Y.Z.)
- College of Horticulture, China Agricultural University, Beijing 100193, China
| | - Hongyang Wang
- State Key Laboratory of Vegetable Biobreeding, Beijing Vegetable Research Center, Beijing Academy of Agriculture and Forestry Science, Beijing 100097, China; (Q.D.); (H.W.); (Y.Q.); (D.W.); (Y.X.); (Y.Z.); (M.P.); (Y.Z.)
- National Engineering Research Center for Vegetables, Beijing Vegetable Research Center, Beijing Academy of Agriculture and Forestry Science, Beijing 100097, China
| | - Yanhong Qiu
- State Key Laboratory of Vegetable Biobreeding, Beijing Vegetable Research Center, Beijing Academy of Agriculture and Forestry Science, Beijing 100097, China; (Q.D.); (H.W.); (Y.Q.); (D.W.); (Y.X.); (Y.Z.); (M.P.); (Y.Z.)
- National Engineering Research Center for Vegetables, Beijing Vegetable Research Center, Beijing Academy of Agriculture and Forestry Science, Beijing 100097, China
| | - Dexin Wang
- State Key Laboratory of Vegetable Biobreeding, Beijing Vegetable Research Center, Beijing Academy of Agriculture and Forestry Science, Beijing 100097, China; (Q.D.); (H.W.); (Y.Q.); (D.W.); (Y.X.); (Y.Z.); (M.P.); (Y.Z.)
- National Engineering Research Center for Vegetables, Beijing Vegetable Research Center, Beijing Academy of Agriculture and Forestry Science, Beijing 100097, China
| | - Yang Xia
- State Key Laboratory of Vegetable Biobreeding, Beijing Vegetable Research Center, Beijing Academy of Agriculture and Forestry Science, Beijing 100097, China; (Q.D.); (H.W.); (Y.Q.); (D.W.); (Y.X.); (Y.Z.); (M.P.); (Y.Z.)
- National Engineering Research Center for Vegetables, Beijing Vegetable Research Center, Beijing Academy of Agriculture and Forestry Science, Beijing 100097, China
| | - Yumeng Zhang
- State Key Laboratory of Vegetable Biobreeding, Beijing Vegetable Research Center, Beijing Academy of Agriculture and Forestry Science, Beijing 100097, China; (Q.D.); (H.W.); (Y.Q.); (D.W.); (Y.X.); (Y.Z.); (M.P.); (Y.Z.)
- College of Horticulture, China Agricultural University, Beijing 100193, China
| | - Manying Pei
- State Key Laboratory of Vegetable Biobreeding, Beijing Vegetable Research Center, Beijing Academy of Agriculture and Forestry Science, Beijing 100097, China; (Q.D.); (H.W.); (Y.Q.); (D.W.); (Y.X.); (Y.Z.); (M.P.); (Y.Z.)
- College of Horticulture, China Agricultural University, Beijing 100193, China
| | - Yinling Zhao
- State Key Laboratory of Vegetable Biobreeding, Beijing Vegetable Research Center, Beijing Academy of Agriculture and Forestry Science, Beijing 100097, China; (Q.D.); (H.W.); (Y.Q.); (D.W.); (Y.X.); (Y.Z.); (M.P.); (Y.Z.)
- College of Horticulture, China Agricultural University, Beijing 100193, China
| | - Xiulan Xu
- State Key Laboratory of Vegetable Biobreeding, Beijing Vegetable Research Center, Beijing Academy of Agriculture and Forestry Science, Beijing 100097, China; (Q.D.); (H.W.); (Y.Q.); (D.W.); (Y.X.); (Y.Z.); (M.P.); (Y.Z.)
- National Engineering Research Center for Vegetables, Beijing Vegetable Research Center, Beijing Academy of Agriculture and Forestry Science, Beijing 100097, China
| | - Haijun Zhang
- State Key Laboratory of Vegetable Biobreeding, Beijing Vegetable Research Center, Beijing Academy of Agriculture and Forestry Science, Beijing 100097, China; (Q.D.); (H.W.); (Y.Q.); (D.W.); (Y.X.); (Y.Z.); (M.P.); (Y.Z.)
- National Engineering Research Center for Vegetables, Beijing Vegetable Research Center, Beijing Academy of Agriculture and Forestry Science, Beijing 100097, China
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Kamran M, Melville KT, Waters MT. Karrikin signalling: impacts on plant development and abiotic stress tolerance. JOURNAL OF EXPERIMENTAL BOTANY 2024; 75:1174-1186. [PMID: 38001035 PMCID: PMC10860534 DOI: 10.1093/jxb/erad476] [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: 07/28/2023] [Accepted: 11/23/2023] [Indexed: 11/26/2023]
Abstract
Plants rely upon a diverse range of metabolites to control growth and development, and to overcome stress that results from suboptimal conditions. Karrikins (KARs) are a class of butenolide compounds found in smoke that stimulate seed germination and regulate various developmental processes in plants. KARs are perceived via a plant α/β-hydrolase called KARRIKIN INSENSITIVE2 (KAI2), which also functions as a receptor for a postulated phytohormone, provisionally termed KAI2 ligand (KL). Considered natural analogues of KL, KARs have been extensively studied for their effects on plant growth and their crosstalk with plant hormones. The perception and response pathway for KAR-KL signalling is closely related to that of strigolactones, another class of butenolides with numerous functions in regulating plant growth. KAR-KL signalling influences seed germination, seedling photomorphogenesis, root system architecture, abiotic stress responses, and arbuscular mycorrhizal symbiosis. Here, we summarize current knowledge of KAR-KL signalling, focusing on its role in plant development, its effects on stress tolerance, and its interaction with other signalling mechanisms.
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Affiliation(s)
- Muhammad Kamran
- School of Molecular Sciences, The University of Western Australia, Perth, WA 6009, Australia
| | - Kim T Melville
- School of Molecular Sciences, The University of Western Australia, Perth, WA 6009, Australia
| | - Mark T Waters
- School of Molecular Sciences, The University of Western Australia, Perth, WA 6009, Australia
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Waters MT, Nelson DC. Karrikin perception and signalling. THE NEW PHYTOLOGIST 2023; 237:1525-1541. [PMID: 36333982 DOI: 10.1111/nph.18598] [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: 07/03/2022] [Accepted: 09/29/2022] [Indexed: 06/16/2023]
Abstract
Karrikins (KARs) are a class of butenolide compounds found in smoke that were first identified as seed germination stimulants for fire-following species. Early studies of KARs classified the germination and postgermination responses of many plant species and investigated crosstalk with plant hormones that regulate germination. The discovery that Arabidopsis thaliana responds to KARs laid the foundation for identifying mutants with altered KAR responses. Genetic analysis of KAR signalling revealed an unexpected link to strigolactones (SLs), a class of carotenoid-derived plant hormones. Substantial progress has since been made towards understanding how KARs are perceived and regulate plant growth, in no small part due to advances in understanding SL perception. KAR and SL signalling systems are evolutionarily related and retain a high degree of similarity. There is strong evidence that KARs are natural analogues of an endogenous signal(s), KAI2 ligand (KL), which remains unknown. KAR/KL signalling regulates many developmental processes in plants including germination, seedling photomorphogenesis, and root and root hair growth. KAR/KL signalling also affects abiotic stress responses and arbuscular mycorrhizal symbiosis. Here, we summarise the current knowledge of KAR/KL signalling and discuss current controversies and unanswered questions in this field.
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Affiliation(s)
- Mark T Waters
- School of Molecular Sciences, University of Western Australia, Perth, WA, 6009, Australia
| | - David C Nelson
- Department of Botany and Plant Sciences, University of California, Riverside, CA, 92521, USA
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