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Li Q, Yu H, Chang W, Chang S, Guzmán M, Faure L, Wallner ES, Yan H, Greb T, Wang L, Yao R, Nelson DC. SMXL5 attenuates strigolactone signaling in Arabidopsis thaliana by inhibiting SMXL7 degradation. MOLECULAR PLANT 2024; 17:631-647. [PMID: 38475994 DOI: 10.1016/j.molp.2024.03.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 01/10/2024] [Accepted: 03/07/2024] [Indexed: 03/14/2024]
Abstract
Hormone-activated proteolysis is a recurring theme of plant hormone signaling mechanisms. In strigolactone signaling, the enzyme receptor DWARF14 (D14) and an F-box protein, MORE AXILLARY GROWTH2 (MAX2), mark SUPPRESSOR OF MAX2 1-LIKE (SMXL) family proteins SMXL6, SMXL7, and SMXL8 for rapid degradation. Removal of these transcriptional corepressors initiates downstream growth responses. The homologous proteins SMXL3, SMXL4, and SMXL5, however, are resistant to MAX2-mediated degradation. We discovered that the smxl4 smxl5 mutant has enhanced responses to strigolactone. SMXL5 attenuates strigolactone signaling by interfering with AtD14-SMXL7 interactions. SMXL5 interacts with AtD14 and SMXL7, providing two possible ways to inhibit SMXL7 degradation. SMXL5 function is partially dependent on an ethylene-responsive-element binding-factor-associated amphiphilic repression (EAR) motif, which typically mediates interactions with the TOPLESS family of transcriptional corepressors. However, we found that loss of the EAR motif reduces SMXL5-SMXL7 interactions and the attenuation of strigolactone signaling by SMXL5. We hypothesize that integration of SMXL5 into heteromeric SMXL complexes reduces the susceptibility of SMXL6/7/8 proteins to strigolactone-activated degradation and that the EAR motif promotes the formation or stability of these complexes. This mechanism may provide a way to spatially or temporally fine-tune strigolactone signaling through the regulation of SMXL5 expression or translation.
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Affiliation(s)
- Qingtian Li
- Department of Botany and Plant Sciences, University of California, Riverside, Riverside, CA 92521, USA; Yazhouwan National Laboratory, Sanya 572025, China; Hainan Seed Industry Laboratory, Sanya 57205, China.
| | - Haiyang Yu
- State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan Provincial Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha 410082, China
| | - Wenwen Chang
- Key Laboratory of Seed Innovation, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang, Hebei 050021, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Sunhyun Chang
- Department of Botany and Plant Sciences, University of California, Riverside, Riverside, CA 92521, USA
| | - Michael Guzmán
- Department of Botany and Plant Sciences, University of California, Riverside, Riverside, CA 92521, USA
| | - Lionel Faure
- School of the Sciences, Biology Division, Texas Woman's University, Denton, TX 76204, USA
| | - Eva-Sophie Wallner
- Centre for Organismal Studies (COS), Heidelberg University, 69120 Heidelberg, Germany
| | - Heqin Yan
- Yazhouwan National Laboratory, Sanya 572025, China
| | - Thomas Greb
- Centre for Organismal Studies (COS), Heidelberg University, 69120 Heidelberg, Germany
| | - Lei Wang
- Key Laboratory of Seed Innovation, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang, Hebei 050021, China
| | - Ruifeng Yao
- State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan Provincial Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha 410082, China.
| | - David C Nelson
- Department of Botany and Plant Sciences, University of California, Riverside, Riverside, CA 92521, USA.
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Drummond RSM, Lee HW, Luo Z, Dakin JF, Janssen BJ, Snowden KC. Varying the expression pattern of the strigolactone receptor gene DAD2 results in phenotypes distinct from both wild type and knockout mutants. FRONTIERS IN PLANT SCIENCE 2023; 14:1277617. [PMID: 37900765 PMCID: PMC10600376 DOI: 10.3389/fpls.2023.1277617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 09/22/2023] [Indexed: 10/31/2023]
Abstract
The action of the petunia strigolactone (SL) hormone receptor DAD2 is dependent not only on its interaction with the PhMAX2A and PhD53A proteins, but also on its expression patterns within the plant. Previously, in a yeast-2-hybrid system, we showed that a series of a single and double amino acid mutants of DAD2 had altered interactions with these binding partners. In this study, we tested the mutants in two plant systems, Arabidopsis and petunia. Testing in Arabidopsis was enabled by creating a CRISPR-Cas9 knockout mutant of the Arabidopsis strigolactone receptor (AtD14). We produced SL receptor activity in both systems using wild type and mutant genes; however, the mutants had functions largely indistinguishable from those of the wild type. The expression of the wild type DAD2 from the CaMV 35S promoter in dad2 petunia produced plants neither quite like the dad2 mutant nor the V26 wild type. These plants had greater height and leaf size although branch number and the plant shape remained more like those of the mutant. These traits may be valuable in the context of a restricted area growing system such as controlled environment agriculture.
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Affiliation(s)
- Revel S. M. Drummond
- The New Zealand Institute for Plant and Food Research Limited, Auckland, New Zealand
| | | | | | | | | | - Kimberley C. Snowden
- The New Zealand Institute for Plant and Food Research Limited, Auckland, New Zealand
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Guercio AM, Palayam M, Shabek N. Strigolactones: diversity, perception, and hydrolysis. PHYTOCHEMISTRY REVIEWS : PROCEEDINGS OF THE PHYTOCHEMICAL SOCIETY OF EUROPE 2023; 22:339-360. [PMID: 37201177 PMCID: PMC10191409 DOI: 10.1007/s11101-023-09853-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 01/03/2023] [Indexed: 05/20/2023]
Abstract
Strigolactones (SLs) are a unique and novel class of phytohormones that regulate numerous processes of growth and development in plants. Besides their endogenous functions as hormones, SLs are exuded by plant roots to stimulate critical interactions with symbiotic fungi but can also be exploited by parasitic plants to trigger their seed germination. In the past decade, since their discovery as phytohormones, rapid progress has been made in understanding the SL biosynthesis and signaling pathway. Of particular interest are the diversification of natural SLs and their exact mode of perception, selectivity, and hydrolysis by their dedicated receptors in plants. Here we provide an overview of the emerging field of SL perception with a focus on the diversity of canonical, non-canonical, and synthetic SL probes. Moreover, this review offers useful structural insights into SL perception, the precise molecular adaptations that define receptor-ligand specificities, and the mechanisms of SL hydrolysis and its attenuation by downstream signaling components.
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Affiliation(s)
- Angelica M Guercio
- Department of Plant Biology, College of Biological Sciences, University of California - Davis, Davis, CA 95616, USA
| | - Malathy Palayam
- Department of Plant Biology, College of Biological Sciences, University of California - Davis, Davis, CA 95616, USA
| | - Nitzan Shabek
- Department of Plant Biology, College of Biological Sciences, University of California - Davis, Davis, CA 95616, USA
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