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Chen B, Fiers M, Dekkers BJW, Maas L, van Esse GW, Angenent GC, Zhao Y, Boutilier K. ABA signalling promotes cell totipotency in the shoot apex of germinating embryos. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:6418-6436. [PMID: 34175924 PMCID: PMC8483786 DOI: 10.1093/jxb/erab306] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 06/25/2021] [Indexed: 05/03/2023]
Abstract
Somatic embryogenesis (SE) is a type of induced cell totipotency where embryos develop from vegetative tissues of the plant instead of from gamete fusion after fertilization. SE can be induced in vitro by exposing explants to growth regulators, such as the auxinic herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). The plant hormone abscisic acid (ABA) has been proposed to be a downstream signalling component at the intersection between 2,4-D- and stress-induced SE, but it is not known how these pathways interact to induce cell totipotency. Here we show that 2,4-D-induced SE from the shoot apex of germinating Arabidopsis thaliana seeds is characterized by transcriptional maintenance of an ABA-dependent seed maturation pathway. Molecular-genetic analysis of Arabidopsis mutants revealed a role for ABA in promoting SE at three different levels: ABA biosynthesis, ABA receptor complex signalling, and ABA-mediated transcription, with essential roles for the ABSCISIC ACID INSENSITIVE 3 (ABI3) and ABI4 transcription factors. Our data suggest that the ability of mature Arabidopsis embryos to maintain the ABA seed maturation environment is an important first step in establishing competence for auxin-induced cell totipotency. This finding provides further support for the role of ABA in directing processes other than abiotic stress response.
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Affiliation(s)
- Baojian Chen
- Bioscience, Wageningen University and Research, AA Wageningen, Netherlands
- Laboratory for Molecular Biology, Wageningen University and Research, AP, Wageningen, Netherlands
| | - Martijn Fiers
- Bioscience, Wageningen University and Research, AA Wageningen, Netherlands
| | - Bas J W Dekkers
- Wageningen Seed Lab, Laboratory for Plant Physiology, Wageningen University and Research Centre, AA, Netherlands
| | - Lena Maas
- Bioscience, Wageningen University and Research, AA Wageningen, Netherlands
- Laboratory for Molecular Biology, Wageningen University and Research, AP, Wageningen, Netherlands
| | - G Wilma van Esse
- Bioscience, Wageningen University and Research, AA Wageningen, Netherlands
- Laboratory for Molecular Biology, Wageningen University and Research, AP, Wageningen, Netherlands
| | - Gerco C Angenent
- Bioscience, Wageningen University and Research, AA Wageningen, Netherlands
- Laboratory for Molecular Biology, Wageningen University and Research, AP, Wageningen, Netherlands
| | - Yang Zhao
- Shanghai Center for Plant Stress Biology, and CAS Center of Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Kim Boutilier
- Bioscience, Wageningen University and Research, AA Wageningen, Netherlands
- Correspondence:
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Spitzer C, Reyes FC, Buono R, Sliwinski MK, Haas TJ, Otegui MS. The ESCRT-related CHMP1A and B proteins mediate multivesicular body sorting of auxin carriers in Arabidopsis and are required for plant development. THE PLANT CELL 2009; 21:749-66. [PMID: 19304934 PMCID: PMC2671707 DOI: 10.1105/tpc.108.064865] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2008] [Revised: 02/16/2009] [Accepted: 03/06/2009] [Indexed: 05/18/2023]
Abstract
Plasma membrane proteins internalized by endocytosis and targeted for degradation are sorted into lumenal vesicles of multivesicular bodies (MVBs) by the endosomal sorting complexes required for transport (ESCRT) machinery. Here, we show that the Arabidopsis thaliana ESCRT-related CHARGED MULTIVESICULAR BODY PROTEIN/CHROMATIN MODIFYING PROTEIN1A (CHMP1A) and CHMP1B proteins are essential for embryo and seedling development. Double homozygous chmp1a chmp1b mutant embryos showed limited polar differentiation and failed to establish bilateral symmetry. Mutant seedlings show disorganized apical meristems and rudimentary true leaves with clustered stomata and abnormal vein patterns. Mutant embryos failed to establish normal auxin gradients. Three proteins involved in auxin transport, PINFORMED1 (PIN1), PIN2, and AUXIN-RESISTANT1 (AUX1) mislocalized to the vacuolar membrane of the mutant. PIN1 was detected in MVB lumenal vesicles of control cells but remained in the limiting membrane of chmp1a chmp1b MVBs. The chmp1a chmp1b mutant forms significantly fewer MVB lumenal vesicles than the wild type. Furthermore, CHMP1A interacts in vitro with the ESCRT-related proteins At SKD1 and At LIP5. Thus, Arabidopsis CHMP1A and B are ESCRT-related proteins with conserved endosomal functions, and the auxin carriers PIN1, PIN2, and AUX1 are ESCRT cargo proteins in the MVB sorting pathway.
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Affiliation(s)
- Christoph Spitzer
- Department of Botany, University of Wisconsin, Madison, Wisconsin 53706, USA
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