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Schuhmann P, Engstler C, Klöpfer K, Gügel IL, Abbadi A, Dreyer F, Leckband G, Bölter B, Hagn F, Soll J, Carrie C. Two wrongs make a right: heat stress reversion of a male-sterile Brassica napus line. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:3531-3551. [PMID: 35226731 PMCID: PMC9162185 DOI: 10.1093/jxb/erac082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Accepted: 02/28/2022] [Indexed: 06/14/2023]
Abstract
Male-sterile lines play important roles in plant breeding to obtain hybrid vigour. The male sterility Lembke (MSL) system is a thermosensitive genic male sterility system of Brassica napus and is one of the main systems used in European rapeseed breeding. Interestingly, the MSL system shows high similarity to the 9012AB breeding system from China, including the ability to revert to fertile in high temperature conditions. Here we demonstrate that the MSL system is regulated by the same restorer of fertility gene BnaC9-Tic40 as the 9012AB system, which is related to the translocon at the inner envelope membrane of chloroplasts 40 (TIC40) from Arabidopsis. The male sterility gene of the MSL system was also identified to encode a chloroplast-localized protein which we call BnChimera; this gene shows high sequence similarity to the sterility gene previously described for the 9012AB system. For the first time, a direct protein interaction between BnaC9-Tic40 and the BnChimera could be demonstrated. In addition, we identify the corresponding amino acids that mediate this interaction and suggest how BnaC9-Tic40 acts as the restorer of fertility. Using an RNA-seq approach, the effects of heat treatment on the male fertility restoration of the C545 MSL system line were investigated. These data demonstrate that many pollen developmental pathways are affected by higher temperatures. It is hypothesized that heat stress reverses the male sterility via a combination of slower production of cell wall precursors in plastids and a slower flower development, which ultimately results in fertile pollen. The potential breeding applications of these results are discussed regarding the use of the MSL system in producing thermotolerant fertile plants.
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Affiliation(s)
- Petra Schuhmann
- Department Biologie I–Botanik, Ludwig-Maximilians-Universität München, Großhadernerstr. 2–4, D-82152 Planegg-Martinsried, Germany
| | - Carina Engstler
- Department Biologie I–Botanik, Ludwig-Maximilians-Universität München, Großhadernerstr. 2–4, D-82152 Planegg-Martinsried, Germany
| | - Kai Klöpfer
- Bavarian NMR Center (BNMRZ) at the Department of Chemistry, Technical University of Munich, Lichtenbergstrasse 4, D-85748 Garching, Germany
| | - Irene L Gügel
- Department Biologie I–Botanik, Ludwig-Maximilians-Universität München, Großhadernerstr. 2–4, D-82152 Planegg-Martinsried, Germany
- Center of Advanced European Studies and Research (caesar), Ludwig-Erhard-Allee 2, D-53175 Bonn, Germany
| | - Amine Abbadi
- NPZ Innovation GmbH, Hohenlieth-Hof, D-24363 Holtsee, Germany
| | - Felix Dreyer
- NPZ Innovation GmbH, Hohenlieth-Hof, D-24363 Holtsee, Germany
| | - Gunhild Leckband
- Norddeutsche Pflanzenzucht Hans-Georg Lembke KG, Hohenlieth-Hof 1, D-24363 Holtsee, Germany
| | - Bettina Bölter
- Department Biologie I–Botanik, Ludwig-Maximilians-Universität München, Großhadernerstr. 2–4, D-82152 Planegg-Martinsried, Germany
| | - Franz Hagn
- Bavarian NMR Center (BNMRZ) at the Department of Chemistry, Technical University of Munich, Lichtenbergstrasse 4, D-85748 Garching, Germany
- Institute of Structural Biology, Helmholtz Zentrum München, Ingolstädter Landstraße 1, D-85764 Neuherberg, Germany
| | - Jürgen Soll
- Department Biologie I–Botanik, Ludwig-Maximilians-Universität München, Großhadernerstr. 2–4, D-82152 Planegg-Martinsried, Germany
- Munich Centre for Integrated Protein Science, CIPSM, Ludwig-Maximilians-Universität München, Feodor-Lynen-Str. 25, D-81377 Munich, Germany
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Richardson LGL, Schnell DJ. Origins, function, and regulation of the TOC-TIC general protein import machinery of plastids. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:1226-1238. [PMID: 31730153 PMCID: PMC7031061 DOI: 10.1093/jxb/erz517] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 11/14/2019] [Indexed: 05/11/2023]
Abstract
The evolution of chloroplasts from the original endosymbiont involved the transfer of thousands of genes from the ancestral bacterial genome to the host nucleus, thereby combining the two genetic systems to facilitate coordination of gene expression and achieve integration of host and organelle functions. A key element of successful endosymbiosis was the evolution of a unique protein import system to selectively and efficiently target nuclear-encoded proteins to their site of function within the chloroplast after synthesis in the cytoplasm. The chloroplast TOC-TIC (translocon at the outer chloroplast envelope-translocon at the inner chloroplast envelope) general protein import system is conserved across the plant kingdom, and is a system of hybrid origin, with core membrane transport components adapted from bacterial protein targeting systems, and additional components adapted from host genes to confer the specificity and directionality of import. In vascular plants, the TOC-TIC system has diversified to mediate the import of specific, functionally related classes of plastid proteins. This functional diversification occurred as the plastid family expanded to fulfill cell- and tissue-specific functions in terrestrial plants. In addition, there is growing evidence that direct regulation of TOC-TIC activities plays an essential role in the dynamic remodeling of the organelle proteome that is required to coordinate plastid biogenesis with developmental and physiological events.
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Affiliation(s)
- Lynn G L Richardson
- Department of Plant Biology, Michigan State University, East Lansing, MI, USA
| | - Danny J Schnell
- Department of Plant Biology, Michigan State University, East Lansing, MI, USA
- Correspondence:
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Schnell DJ. The TOC GTPase Receptors: Regulators of the Fidelity, Specificity and Substrate Profiles of the General Protein Import Machinery of Chloroplasts. Protein J 2020; 38:343-350. [PMID: 31201619 PMCID: PMC6589150 DOI: 10.1007/s10930-019-09846-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
More than 2500 nuclear encoded preproteins are required for the function of chloroplasts in terrestrial plants. These preproteins are imported into chloroplasts via the concerted action of two multi-subunit translocons of the outer (TOC) and inner (TIC) membranes of the chloroplast envelope. This general import machinery functions to recognize and import proteins with high fidelity and efficiency to ensure that organelle biogenesis is properly coordinated with developmental and physiological events. Two components of the TOC machinery, Toc34 and Toc159, act as the primary receptors for preproteins at the chloroplast surface. They interact with the intrinsic targeting signals (transit peptides) of preproteins to mediate the selectivity of targeting, and they contribute to the quality control of import by constituting a GTP-dependent checkpoint in the import reaction. The TOC receptor family has expanded to regulate the import of distinct classes of preproteins that are required for remodeling of organelle proteomes during plastid-type transitions that accompany developmental changes. As such, the TOC receptors function as central regulators of the fidelity, specificity and selectivity of the general import machinery, thereby contributing to the integration of protein import with plastid biogenesis.
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Affiliation(s)
- Danny J Schnell
- Department of Plant Biology, Michigan State University, East Lansing, MI, USA.
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Bölter B, Soll J. Once upon a Time - Chloroplast Protein Import Research from Infancy to Future Challenges. MOLECULAR PLANT 2016; 9:798-812. [PMID: 27142186 DOI: 10.1016/j.molp.2016.04.014] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Revised: 04/25/2016] [Accepted: 04/27/2016] [Indexed: 05/08/2023]
Abstract
Protein import into chloroplasts has been a focus of research for several decades. The first publications dealing with this fascinating topic appeared in the 1970s. From the initial realization that many plastid proteins are being encoded for in the nucleus and require transport into their target organelle to the identification of import components in the cytosol, chloroplast envelopes, and stroma, as well as elucidation of some mechanistic details, more fascinating aspects are still being unraveled. With this overview, we present a survey of the beginnings of chloroplast protein import research, the first steps on this winding road, and end with a glimpse into the future.
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Affiliation(s)
- Bettina Bölter
- Department Biologie I-Botanik, Ludwig-Maximilians-Universität, Großhaderner Straße 2-4, 82152 Planegg-Martinsried, Germany; Munich Center for Integrated Protein Science CiPSM, Ludwig-Maximilians-Universität, Feodor-Lynen-Strasse 25, 81377 Munich, Germany.
| | - Jürgen Soll
- Department Biologie I-Botanik, Ludwig-Maximilians-Universität, Großhaderner Straße 2-4, 82152 Planegg-Martinsried, Germany; Munich Center for Integrated Protein Science CiPSM, Ludwig-Maximilians-Universität, Feodor-Lynen-Strasse 25, 81377 Munich, Germany
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Mackiewicz P, Bodył A, Gagat P. Protein import into the photosynthetic organelles of Paulinella chromatophora and its implications for primary plastid endosymbiosis. Symbiosis 2012; 58:99-107. [PMID: 23482692 PMCID: PMC3589627 DOI: 10.1007/s13199-012-0202-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Accepted: 11/20/2012] [Indexed: 10/27/2022]
Abstract
The rhizarian amoeba Paulinella chromatophora harbors two photosynthetically active organelles of cyanobacterial origin that have been acquired independently of classic primary plastids. Because their acquisition did take place relatively recently, they are expected to provide new insight into the ancient cyanobacterial primary endosymbiosis. During the process of Paulinella endosymbiont-to-organelle transformation, more than 30 genes have been transferred from the organelle to the host nuclear genome via endosymbiotic gene transfer (EGT). The article discusses step-by-step protein import of EGT-derived proteins into Paulinella photosynthetic organelles with the emphasis on the nature of their targeting signals and the final passage of proteins through the inner organelle membrane. The latter most probably involves a simplified Tic translocon composed of Tic21- and Tic32-like proteins as well as a Hsp70-based motor responsible for pulling of imported proteins into the organelle matrix. Our results indicate that although protein translocation across the inner membrane of Paulinella photosynthetic organelles seems to resemble the one in classic primary plastids, the transport through the outer membrane does not. The differences could result from distinct integration pathways of Paulinella photosynthetic organelles and primary plastids with their respective host cells.
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Affiliation(s)
- Paweł Mackiewicz
- Department of Genomics, Faculty of Biotechnology, University of Wrocław, ul. Przybyszewskiego 63/77, 51-148 Wrocław, Poland
| | - Andrzej Bodył
- Laboratory of Evolutionary Protistology, Division of Invertebrate Biology, Evolution and Conservation, Faculty of Biological Sciences, University of Wrocław, ul. Przybyszewskiego 63/77, 51-148 Wrocław, Poland
| | - Przemysław Gagat
- Department of Genomics, Faculty of Biotechnology, University of Wrocław, ul. Przybyszewskiego 63/77, 51-148 Wrocław, Poland
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