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Pečenková T, Potocký M, Stegmann M. More than meets the eye: knowns and unknowns of the trafficking of small secreted proteins in Arabidopsis. JOURNAL OF EXPERIMENTAL BOTANY 2024; 75:3713-3730. [PMID: 38693754 DOI: 10.1093/jxb/erae172] [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: 12/31/2023] [Accepted: 05/01/2024] [Indexed: 05/03/2024]
Abstract
Small proteins represent a significant portion of the cargo transported through plant secretory pathways, playing crucial roles in developmental processes, fertilization, and responses to environmental stresses. Despite the importance of small secreted proteins, substantial knowledge gaps persist regarding the regulatory mechanisms governing their trafficking along the secretory pathway, and their ultimate localization or destination. To address these gaps, we conducted a comprehensive literature review, focusing particularly on trafficking and localization of Arabidopsis small secreted proteins with potential biochemical and/or signaling roles in the extracellular space, typically those within the size range of 101-200 amino acids. Our investigation reveals that while at least six members of the 21 mentioned families have a confirmed extracellular localization, eight exhibit intracellular localization, including cytoplasmic, nuclear, and chloroplastic locations, despite the presence of N-terminal signal peptides. Further investigation into the trafficking and secretion mechanisms of small protein cargo could not only deepen our understanding of plant cell biology and physiology but also provide a foundation for genetic manipulation strategies leading to more efficient plant cultivation.
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Affiliation(s)
- Tamara Pečenková
- Institute of Experimental Botany of the Czech Academy of Sciences, Rozvojová 263, 165 02, Prague 6, Czech Republic
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Viničná 5, 128 44, Prague 2, Czech Republic
| | - Martin Potocký
- Institute of Experimental Botany of the Czech Academy of Sciences, Rozvojová 263, 165 02, Prague 6, Czech Republic
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Viničná 5, 128 44, Prague 2, Czech Republic
| | - Martin Stegmann
- Technical University Munich, School of Life Sciences, Phytopathology, Emil-Ramann-Str. 2, 85354 Freising, Germany
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Taleski M, Jin M, Chapman K, Taylor K, Winning C, Frank M, Imin N, Djordjevic MA. CEP hormones at the nexus of nutrient acquisition and allocation, root development, and plant-microbe interactions. JOURNAL OF EXPERIMENTAL BOTANY 2024; 75:538-552. [PMID: 37946363 PMCID: PMC10773996 DOI: 10.1093/jxb/erad444] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 11/04/2023] [Indexed: 11/12/2023]
Abstract
A growing understanding is emerging of the roles of peptide hormones in local and long-distance signalling that coordinates plant growth and development as well as responses to the environment. C-TERMINALLY ENCODED PEPTIDE (CEP) signalling triggered by its interaction with CEP RECEPTOR 1 (CEPR1) is known to play roles in systemic nitrogen (N) demand signalling, legume nodulation, and root system architecture. Recent research provides further insight into how CEP signalling operates, which involves diverse downstream targets and interactions with other hormone pathways. Additionally, there is emerging evidence of CEP signalling playing roles in N allocation, root responses to carbon levels, the uptake of other soil nutrients such as phosphorus and sulfur, root responses to arbuscular mycorrhizal fungi, plant immunity, and reproductive development. These findings suggest that CEP signalling more broadly coordinates growth across the whole plant in response to diverse environmental cues. Moreover, CEP signalling and function appear to be conserved in angiosperms. We review recent advances in CEP biology with a focus on soil nutrient uptake, root system architecture and organogenesis, and roles in plant-microbe interactions. Furthermore, we address knowledge gaps and future directions in this research field.
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Affiliation(s)
- Michael Taleski
- Division of Plant Sciences, Research School of Biology, College of Science, The Australian National University, Canberra, ACT, 2601Australia
| | - Marvin Jin
- Division of Plant Sciences, Research School of Biology, College of Science, The Australian National University, Canberra, ACT, 2601Australia
| | - Kelly Chapman
- Division of Plant Sciences, Research School of Biology, College of Science, The Australian National University, Canberra, ACT, 2601Australia
| | - Katia Taylor
- CSIRO Agriculture and Food, Canberra, ACT, 2601, Australia
| | - Courtney Winning
- Division of Plant Sciences, Research School of Biology, College of Science, The Australian National University, Canberra, ACT, 2601Australia
| | - Manuel Frank
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark
| | - Nijat Imin
- School of Science, Western Sydney University, Penrith, New South Wales 2751, Australia
| | - Michael A Djordjevic
- Division of Plant Sciences, Research School of Biology, College of Science, The Australian National University, Canberra, ACT, 2601Australia
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Chapman K, Taleski M, Frank M, Djordjevic MA. C-TERMINALLY ENCODED PEPTIDE (CEP) and cytokinin hormone signaling intersect to promote shallow lateral root angles. JOURNAL OF EXPERIMENTAL BOTANY 2024; 75:631-641. [PMID: 37688302 DOI: 10.1093/jxb/erad353] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 09/07/2023] [Indexed: 09/10/2023]
Abstract
Root system architecture (RSA) influences the acquisition of heterogeneously dispersed soil nutrients. Cytokinin and C-TERMINALLY ENCODED PEPTIDE (CEP) hormones affect RSA, in part by controlling the angle of lateral root (LR) growth. Both hormone pathways converge on CEP DOWNSTREAM 1 (CEPD1) and CEPD2 to control primary root growth; however, a role for CEPDs in controlling the growth angle of LRs is unknown. Using phenotyping combined with genetic and grafting approaches, we show that CEP hormone-mediated shallower LR growth requires cytokinin biosynthesis and perception in roots via ARABIDOPSIS HISTIDINE KINASE 2 (AHK2) and AHK3. Consistently, cytokinin biosynthesis and ahk2,3 mutants phenocopied the steeper root phenotype of cep receptor 1 (cepr1) mutants on agar plates, and CEPR1 was required for trans-Zeatin (tZ)-type cytokinin-mediated shallower LR growth. In addition, the cepd1,2 mutant was less sensitive to CEP and tZ, and showed basally steeper LRs on agar plates. Cytokinin and CEP pathway mutants were grown in rhizoboxes to define the role of these pathways in controlling RSA. Only cytokinin receptor mutants and cepd1,2 partially phenocopied the steeper-rooted phenotype of cepr1 mutants. These results show that CEP and cytokinin signaling intersect to promote shallower LR growth, but additional components contribute to the cepr1 phenotype in soil.
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Affiliation(s)
- Kelly Chapman
- Division of Plant Sciences, Research School of Biology, College of Science, The Australian National University, Canberra, ACT, 2601Australia
| | - Michael Taleski
- Division of Plant Sciences, Research School of Biology, College of Science, The Australian National University, Canberra, ACT, 2601Australia
| | - Manuel Frank
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark
| | - Michael A Djordjevic
- Division of Plant Sciences, Research School of Biology, College of Science, The Australian National University, Canberra, ACT, 2601Australia
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Laffont C, Frugier F. Rhizobium symbiotic efficiency meets CEP signaling peptides. THE NEW PHYTOLOGIST 2024; 241:24-27. [PMID: 37924218 DOI: 10.1111/nph.19367] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2023] [Accepted: 10/13/2023] [Indexed: 11/06/2023]
Abstract
C-terminally encoded peptides (CEP) signaling peptides are drivers of systemic pathways regulating nitrogen (N) acquisition in different plants, from Arabidopsis to legumes, depending on mineral N availability (e.g. nitrate) and on the whole plant N demand. Recent studies in the Medicago truncatula model legume revealed how root-produced CEP peptides control the root competence for endosymbiosis with N fixing rhizobia soil bacteria through the activity of the Compact Root Architecture 2 (CRA2) CEP receptor in shoots. Among CEP genes, MtCEP7 was shown to be tightly linked to nodulation, and the dynamic temporal regulation of its expression reflects the plant ability to maintain a different symbiotic root competence window depending on the symbiotic efficiency of the rhizobium strain, as well as to reinitiate a new window of root competence for nodulation.
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Affiliation(s)
- Carole Laffont
- Institute of Plant Sciences Paris Saclay (IPS2), CNRS, Paris-Saclay University, Paris-Cité University, INRAE, Univ d'Evry, Bat. 630, Avenue des Sciences, Gif-sur-Yvette, 91190, France
| | - Florian Frugier
- Institute of Plant Sciences Paris Saclay (IPS2), CNRS, Paris-Saclay University, Paris-Cité University, INRAE, Univ d'Evry, Bat. 630, Avenue des Sciences, Gif-sur-Yvette, 91190, France
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Li C, Hu Q, Luo Z, Wang X, Tang W, Lu H, Ma C, Kong X. C-terminally encoded peptides act as signals to increase cotton root nitrate uptake under nonuniform salinity. PLANT PHYSIOLOGY 2023; 194:530-545. [PMID: 37757884 DOI: 10.1093/plphys/kiad513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 08/31/2023] [Accepted: 09/01/2023] [Indexed: 09/29/2023]
Abstract
Soil salinity is often heterogeneous in saline fields. Nonuniform root salinity increases nitrate uptake into cotton (Gossypium hirsutum) root portions exposed to low salinity, which may be regulated by root portions exposed to high salinity through a systemic long-distance signaling mechanism. However, the signals transmitted between shoots and roots and their precise molecular mechanisms for regulating nitrate uptake remain unknown. Here, we showed that nonuniform root salinity treatment using split-root systems increases the expression of C-TERMINALLY ENCODED PEPTIDE (GhCEP) genes in high-saline-treated root portions. GhCEP peptides originating in high-saline-treated root portions act as ascending long-distance mobile signals transported to the shoots to promote the expression of CEP DOWNSTREAM (GhCEPD) genes by inducing the expression of CEP receptor (GhCEPR) genes. The shoot-derived GhCEPD polypeptides act as descending mobile signals transported to the roots through the phloem, increasing the expression of nitrate transport genes NITRATE TRANSPORTER 1.1 (GhNRT1.1), GhNRT2.1, and GhNRT1.5 in nonsaline-treated root portions, thereby increasing nitrate uptake in the nonsaline-treated root portions. This study indicates that GhCEP and GhCEPD signals are transported between roots and shoots to increase nitrate uptake in cotton, and the transport from the nonsaline root side is in response to nonuniform root salinity distribution.
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Affiliation(s)
- Chenyang Li
- Institute of Industrial Crops, Shandong Key Lab for Cotton Culture and Physiology, Shandong Academy of Agricultural Sciences, Jinan 250100, PR China
- College of Life Sciences, Shandong Normal University, Jinan 250014, PR China
| | - Qiuyue Hu
- Institute of Industrial Crops, Shandong Key Lab for Cotton Culture and Physiology, Shandong Academy of Agricultural Sciences, Jinan 250100, PR China
- College of Life Sciences, Shandong Normal University, Jinan 250014, PR China
| | - Zhen Luo
- Institute of Industrial Crops, Shandong Key Lab for Cotton Culture and Physiology, Shandong Academy of Agricultural Sciences, Jinan 250100, PR China
| | - Xiaowen Wang
- Institute of Industrial Crops, Shandong Key Lab for Cotton Culture and Physiology, Shandong Academy of Agricultural Sciences, Jinan 250100, PR China
- College of Life Sciences, Shandong Normal University, Jinan 250014, PR China
| | - Wei Tang
- Institute of Industrial Crops, Shandong Key Lab for Cotton Culture and Physiology, Shandong Academy of Agricultural Sciences, Jinan 250100, PR China
| | - Hequan Lu
- Institute of Industrial Crops, Shandong Key Lab for Cotton Culture and Physiology, Shandong Academy of Agricultural Sciences, Jinan 250100, PR China
| | - Changle Ma
- College of Life Sciences, Shandong Normal University, Jinan 250014, PR China
| | - Xiangqiang Kong
- Institute of Industrial Crops, Shandong Key Lab for Cotton Culture and Physiology, Shandong Academy of Agricultural Sciences, Jinan 250100, PR China
- College of Life Sciences, Shandong Normal University, Jinan 250014, PR China
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Chaulagain D, Schnabel E, Lin EX, Garcia RR, Noorai RE, Müller LM, Frugoli JA. TML1 AND TML2 SYNERGISTICALLY REGULATE NODULATION BUT NOT ARBUSCULAR MYCORRHIZA IN MEDICAGO TRUNCATULA. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.07.570674. [PMID: 38106087 PMCID: PMC10723381 DOI: 10.1101/2023.12.07.570674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Two symbiotic processes, nodulation and arbuscular mycorrhiza, are primarily controlled by the plant's need for nitrogen (N) and phosphorus (P), respectively. Autoregulation of Nodulation (AON) and Autoregulation of Mycorrhization (AOM) share multiple components - plants that make too many nodules usually have higher arbuscule density. The protein TML (TOO MUCH LOVE) was shown to function in roots to maintain susceptibly to rhizobial infection under low N conditions and control nodule number through AON in Lotus japonicus. M. truncatula has two sequence homologs: MtTML1 and MtTML2. We report the generation of stable single and double mutants harboring multiple allelic variations in MtTML1 and MtTML2 using CRISPR-Cas9 targeted mutagenesis and screening of a transposon mutagenesis library. Plants containing single mutations in either gene produced twice the nodules of wild type plants whereas plants containing mutations in both genes displayed a synergistic effect, forming 20x more nodules and short roots compared to wild type plants. The synergistic effect on nodulation was maintained in the presence of 10mM nitrogen, but not observed in root length phenotypes. Examination of expression and heterozygote effects suggest genetic compensation may play a role in the observed synergy. However, plants with mutations in both TMLs had no detectable change in arbuscular mycorrhizal associations, suggesting that MtTMLs are specific to nodulation and nitrate signaling. The mutants created will be useful tools to dissect the mechanism of synergistic action of MtTML1 and MtTML2 in M. truncatula nodulation as well as the separation of AON from AOM.
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