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Noll GA, Furch ACU, Rose J, Visser F, Prüfer D. Guardians of the phloem - forisomes and beyond. New Phytol 2022; 236:1245-1260. [PMID: 36089886 DOI: 10.1111/nph.18476] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 07/27/2022] [Indexed: 06/15/2023]
Abstract
The phloem is a highly specialized vascular tissue that forms a fundamentally important transport and signaling pathway in plants. It is therefore a system worth protecting. The main function of the phloem is to transport the products of photosynthesis throughout the whole plant, but it also transports soluble signaling molecules and propagates electrophysiological signals. The phloem is constantly threatened by mechanical injuries, phloem-sucking pests and parasites, and the spread of pathogens, which has led to the evolution of efficient defense mechanisms. One such mechanism involves structural phloem proteins, which are thought to facilitate sieve element occlusion following injury and to defend the plant against pathogens. In leguminous plants, specialized structural phloem proteins known as forisomes form unique mechanoproteins via sophisticated molecular interaction and assembly mechanisms, thus enabling reversible sieve element occlusion. By understanding the structure and function of forisomes and other structural phloem proteins, we can develop a toolbox for biotechnological applications in material science and medicine. Furthermore, understanding the involvement of structural phloem proteins in plant defense mechanisms will allow phloem engineering as a new strategy for the development of crop varieties that are resistant to pests, pathogens and parasites.
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Affiliation(s)
- Gundula A Noll
- Institute of Plant Biology and Biotechnology, University of Muenster, Schlossplatz 8, 48143, Muenster, Germany
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Schlossplatz 8, 48143, Muenster, Germany
| | - Alexandra C U Furch
- Matthias Schleiden Institute for Genetics, Bioinformatics and Molecular Botany, Friedrich Schiller University Jena, Dornburger Straße 159, 07743, Jena, Germany
| | - Judith Rose
- Institute of Plant Biology and Biotechnology, University of Muenster, Schlossplatz 8, 48143, Muenster, Germany
| | - Franziska Visser
- Institute of Plant Biology and Biotechnology, University of Muenster, Schlossplatz 8, 48143, Muenster, Germany
| | - Dirk Prüfer
- Institute of Plant Biology and Biotechnology, University of Muenster, Schlossplatz 8, 48143, Muenster, Germany
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Schlossplatz 8, 48143, Muenster, Germany
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2
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Garg V, Kühn C. What determines the composition of the phloem sap? Is there any selectivity filter for macromolecules entering the phloem sieve elements? Plant Physiol Biochem 2020; 151:284-291. [PMID: 32248039 DOI: 10.1016/j.plaphy.2020.03.023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 03/18/2020] [Indexed: 06/11/2023]
Abstract
In view of recent findings, it is still a matter of debate whether the composition of the phloem sap of higher plants is specific and based on a plasmodesmal selectivity filter for macromolecular transport, or whether simply related to size, abundance and half-life of the macromolecules within the phloem sap. A range of reports indicates specific function of phloem-mobile signaling molecules such as the florigen making it indispensable to discriminate specific macromolecules entering the phloem from others which cannot cross this selectivity filter. Nevertheless, several findings have discussed for a non-selective transport via plasmodesmata, or contamination of the phloem sap by degradation products coming from immature still developing young sieve elements undergoing differentiation. Here, we discuss several possibilities, and raise the question how selectivity of the phloem sap composition could be achieved thereby focusing on mobility and dynamics of sucrose transporter mRNA and proteins.
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Affiliation(s)
- Varsha Garg
- Institute of Biology, Department of Plant Physiology, Humboldt-Universität zu Berlin, Philippstr. 13, Building 12, 10115, Berlin, Germany
| | - Christina Kühn
- Institute of Biology, Department of Plant Physiology, Humboldt-Universität zu Berlin, Philippstr. 13, Building 12, 10115, Berlin, Germany.
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Mullendore DL, Ross-Elliott T, Liu Y, Hellmann HH, Roalson EH, Peters WS, Knoblauch M. Non-dispersive phloem-protein bodies (NPBs) of Populus trichocarpa consist of a SEOR protein and do not respond to cell wounding and Ca 2. PeerJ 2018; 6:e4665. [PMID: 29682428 PMCID: PMC5909683 DOI: 10.7717/peerj.4665] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Accepted: 04/04/2018] [Indexed: 12/20/2022] Open
Abstract
Differentiating sieve elements in the phloem of angiosperms produce abundant phloem-specific proteins before their protein synthesis machinery is degraded. These P-proteins initially form dense bodies, which disperse into individual filaments when the sieve element matures. In some cases, however, the dense protein agglomerations remain intact and are visible in functional sieve tubes as non-dispersive P-protein bodies, or NPBs. Species exhibiting NPBs are distributed across the entire angiosperm clade. We found that NPBs in the model tree, Populus trichocarpa, resemble the protein bodies described from other species of the order Malpighiales as they all consist of coaligned tubular fibrils bundled in hexagonal symmetry. NPBs of all Malpighiales tested proved unresponsive to sieve tube wounding and Ca2+. The P. trichocarpa NPBs consisted of a protein encoded by a gene that in the genome database of this species had been annotated as a homolog of SEOR1 (sieve element occlusion-related 1) in Arabidopsis. Sequencing of the gene in our plants corroborated this interpretation, and we named the gene PtSEOR1. Previously characterized SEOR proteins form irregular masses of P-protein slime in functional sieve tubes. We conclude that a subgroup of these proteins is involved in the formation of NPBs at least in the Malpighiales, and that these protein bodies have no role in rapid wound responses of the sieve tube network.
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Affiliation(s)
- Daniel L Mullendore
- School of Biological Sciences, Washington State University, Pullman, WA, USA
| | - Timothy Ross-Elliott
- Biology Department, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Yan Liu
- School of Biological Sciences, Washington State University, Pullman, WA, USA
| | - Hanjo H Hellmann
- School of Biological Sciences, Washington State University, Pullman, WA, USA
| | - Eric H Roalson
- School of Biological Sciences, Washington State University, Pullman, WA, USA
| | - Winfried S Peters
- School of Biological Sciences, Washington State University, Pullman, WA, USA
| | - Michael Knoblauch
- School of Biological Sciences, Washington State University, Pullman, WA, USA
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Zielonka S, Ernst AM, Hawat S, Twyman RM, Prüfer D, Noll GA. Characterization of five subgroups of the sieve element occlusion gene family in Glycine max reveals genes encoding non-forisome P-proteins, forisomes and forisome tails. Plant Mol Biol 2014; 86:51-67. [PMID: 24928491 DOI: 10.1007/s11103-014-0211-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Accepted: 06/04/2014] [Indexed: 06/03/2023]
Abstract
P-proteins are structural phloem proteins discussed to be involved in the rapid sealing of injured sieve elements. P-proteins are found in all dicotyledonous and some monocotyledonous plants, but additional crystalloid P-proteins, known as forisomes, have evolved solely in the Fabaceae. Both types are encoded by members of the sieve element occlusion (SEO) gene family, which comprises seven phylogenetic subgroups. The Fabaceae-specific subgroup 1 contains genes encoding forisome subunits in e.g. Medicago truncatula, Vicia faba, Dipteryx panamensis and Canavalia gladiata whereas basal subgroup 5 encodes P-proteins in Nicotiana tabacum (tobacco) and Arabidopsis thaliana. The function of remaining subgroups is still unknown. We chose Glycine max (soybean) as a model to investigate SEO proteins representing different subgroups in one species. We isolated native P-proteins to determine the SEO protein composition and analyzed the expression pattern, localization and structure of the G. max SEO proteins representing five of the subgroups. We found that subgroup 1 GmSEO genes encode forisome subunits, a member of subgroup 5 encodes a non-forisome P-protein and subgroup 2 GmSEO genes encode the components of forisome tails, which are present in a restricted selection of Fabaceaen species. We therefore present the first molecular characterization of a Fabaceae non-forisome P-protein and the first evidence that forisome tails are encoded by a phylogenetically-distinct branch of the SEO gene family.
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Affiliation(s)
- Sascia Zielonka
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Schlossplatz 8, 48143, Münster, Germany
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Srivastava VK, Raikwar S, Tuteja N. Cloning and functional characterization of the promoter of PsSEOF1 gene from Pisum sativum under different stress conditions using Agrobacterium-mediated transient assay. Plant Signal Behav 2014; 9:e29626. [PMID: 25763698 PMCID: PMC4205139 DOI: 10.4161/psb.29626] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 06/17/2014] [Accepted: 06/17/2014] [Indexed: 05/29/2023]
Abstract
PsSEOF1, a SEO (sieve element occlusion) gene family protein (forisome) is calcium powered motor protein and is located close to plasma membrane of sieve element. In sieve element (SE) it senses the calcium ion levels and undergoes ATP-independent conformational shifts. Forisome, meaning gate-bodies (Latin foris: wing of a gate; Greek soma: body). Recent reports show that SEO gene family protein can prevent the loss of nutrient rich photoassimilate upon wound injury. The regulation of SEO protein forisome under abiotic/ biotic stress is still unknown. The analysis of cis-regulatory element present in the upstream region is not well understood. Tissue specific promoters guarantee correct expression when it perceives particular stimuli. Here we report isolation of tissue specific promoter of PsSEOF1 was isolated by gene walking PCR from P. sativum (pea) genomic DNA library constructed by BD genome walker kit. In silico analysis revealed several putative cis element within this promoter sequence like wound response, cold, dehydration. Putative elements which might be required for its vascular tissue specificity has also been identified. The GUS activities of PsSEOF1 promoter-GUS chimeric construct in the agroinfiltrated leaves under different environmental stress abiotic and biotic like wound, cold, salt and phytohormones has shown high level of GUS activity. To identify the activity of PsSEOF1 promoter under different stress condition an Agrobacterium-mediated transient expression of tobacco plants were subjected to histochemical GUS staining. Stress-inducible nature of PsSEOF1 promoter opens possibility for the study of the PsSEOF1 gene regulation under stress condition. The isolated promoter sequence could serve as an important candidate for tissue specific promoter in genetic engineering of plant under stress conditions.
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Affiliation(s)
- Vineet Kumar Srivastava
- International Centre for Genetic Engineering and Biotechnology; Aruna Asaf Ali Marg; New Delhi, India
| | - Shailendra Raikwar
- International Centre for Genetic Engineering and Biotechnology; Aruna Asaf Ali Marg; New Delhi, India
| | - Narendra Tuteja
- International Centre for Genetic Engineering and Biotechnology; Aruna Asaf Ali Marg; New Delhi, India
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Srivastava VK, Tuteja R, Tuteja N. Calcium-energized motor protein forisome controls damage in phloem: potential applications as biomimetic "smart" material. Crit Rev Biotechnol 2013; 35:173-83. [PMID: 24020505 DOI: 10.3109/07388551.2013.823598] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Forisomes are ATP independent, mechanically active proteins from the Fabaceae family (also called Leguminosae). These proteins are located in sieve tubes of phloem and function to prevent loss of nutrient-rich photoassimilates, upon mechanical injury/wounding. Forisomes are SEO (sieve element occlusion) gene family proteins that have recently been shown to be involved in wound sealing mechanism. Recent findings suggest that forisomes could act as an ideal model to study self assembly mechanism for the development of nanotechnological devices like microinstruments, the microfluidic system frequently used in space exploration missions. Technology enabling improvement in micro instruments has been identified as a key technology by NASA in future space exploration missions. Forisomes are designated as biomimetic smart materials which are calcium-energized motor proteins. Since forisomes are biomolecules from plant systems it can be doctored through genetic engineering. In contrast, "smart" materials which are not derived from plants are difficult to modify in their properties. Current levels of understanding about forisomes conformational shifts with respect to calcium ions and pH changes requires supplement of future advances with relation to its 3D structure to understand self assembly processes. In plant systems it forms blood clots in the form of occlusions to prevent nutrient fluid leakage and thus proves to be a unique damage control system of phloem tissue.
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Jekat SB, Ernst AM, von Bohl A, Zielonka S, Twyman RM, Noll GA, Prüfer D. P-proteins in Arabidopsis are heteromeric structures involved in rapid sieve tube sealing. Front Plant Sci 2013; 4:225. [PMID: 23840197 PMCID: PMC3700381 DOI: 10.3389/fpls.2013.00225] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Accepted: 06/10/2013] [Indexed: 05/05/2023]
Abstract
Structural phloem proteins (P-proteins) are characteristic components of the sieve elements in all dicotyledonous and many monocotyledonous angiosperms. Tobacco P-proteins were recently confirmed to be encoded by the widespread sieve element occlusion (SEO) gene family, and tobacco SEO proteins were shown to be directly involved in sieve tube sealing thus preventing the loss of photosynthate. Analysis of the two Arabidopsis SEO proteins (AtSEOa and AtSEOb) indicated that the corresponding P-protein subunits do not act in a redundant manner. However, there are still pending questions regarding the interaction properties and specific functions of AtSEOa and AtSEOb as well as the general function of structural P-proteins in Arabidopsis. In this study, we characterized the Arabidopsis P-proteins in more detail. We used in planta bimolecular fluorescence complementation assays to confirm the predicted heteromeric interactions between AtSEOa and AtSEOb. Arabidopsis mutants depleted for one or both AtSEO proteins lacked the typical P-protein structures normally found in sieve elements, underlining the identity of AtSEO proteins as P-proteins and furthermore providing the means to determine the role of Arabidopsis P-proteins in sieve tube sealing. We therefore developed an assay based on phloem exudation. Mutants with reduced AtSEO expression levels lost twice as much photosynthate following injury as comparable wild-type plants, confirming that Arabidopsis P-proteins are indeed involved in sieve tube sealing.
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Affiliation(s)
- Stephan B. Jekat
- Stephan B. Jekat and Antonia M. Ernst have contributed equally to this work.
| | - Antonia M. Ernst
- Stephan B. Jekat and Antonia M. Ernst have contributed equally to this work.
| | - Andreas von Bohl
- Institute of Plant Biology and Biotechnology, University of Münster, MünsterGermany
- Institute for Molecular Biotechnology, Rheinisch-Westfaelische Technische Hochschule Aachen UniversityAachen, Germany
| | - Sascia Zielonka
- Fraunhofer Institute for Molecular Biology and Applied Ecology, MünsterGermany
| | | | - Gundula A. Noll
- Institute of Plant Biology and Biotechnology, University of Münster, MünsterGermany
| | - Dirk Prüfer
- Fraunhofer Institute for Molecular Biology and Applied Ecology, MünsterGermany
- Institute of Plant Biology and Biotechnology, University of Münster, MünsterGermany
- *Correspondence: Dirk Prüfer, Institute of Plant Biology and Biotechnology, University of Münster, Münster, Germany; Fraunhofer Institute for Molecular Biology and Applied Ecology, Schlossplatz 8, 48143 Münster, Germanye-mail:
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Abstract
Angiosperms transport their photoassimilates through sieve tubes, which comprise longitudinally-connected sieve elements. In dicots and also some monocots, the sieve elements contain parietal structural proteins known as phloem proteins or P-proteins. Following injury, P proteins disperse and accumulate as viscous plugs at the sieve plates to prevent the loss of valuable transport sugars. Tobacco (Nicotiana tabacum) P-proteins are multimeric complexes comprising subunits encoded by members of the SEO (sieve element occlusion) gene family. The existence of multiple subunits suggests that P-protein assembly involves interactions between SEO proteins, but this process is largely uncharacterized and it is unclear whether the different subunits perform unique roles or are redundant. We therefore extended our analysis of the tobacco P-proteins NtSEO1 and NtSEO2 to investigate potential interactions between them, and found that both proteins can form homomeric and heteromeric complexes in planta.
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Affiliation(s)
- Stephan B. Jekat
- Fraunhofer Institute for Molecular Biology and Applied Ecology (IME); Münster, Germany
| | - Antonia M. Ernst
- Fraunhofer Institute for Molecular Biology and Applied Ecology (IME); Münster, Germany
| | - Sascia Zielonka
- Fraunhofer Institute for Molecular Biology and Applied Ecology (IME); Münster, Germany
| | - Gundula A. Noll
- Institute of Plant Biology and Biotechnology; University of Muenster; Münster, Germany
| | - Dirk Prüfer
- Fraunhofer Institute for Molecular Biology and Applied Ecology (IME); Münster, Germany
- Institute of Plant Biology and Biotechnology; University of Muenster; Münster, Germany
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Ernst AM, Jekat SB, Zielonka S, Müller B, Neumann U, Rüping B, Twyman RM, Krzyzanek V, Prüfer D, Noll GA. Sieve element occlusion (SEO) genes encode structural phloem proteins involved in wound sealing of the phloem. Proc Natl Acad Sci U S A 2012; 109:E1980-9. [PMID: 22733783 PMCID: PMC3396537 DOI: 10.1073/pnas.1202999109] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The sieve element occlusion (SEO) gene family originally was delimited to genes encoding structural components of forisomes, which are specialized crystalloid phloem proteins found solely in the Fabaceae. More recently, SEO genes discovered in various non-Fabaceae plants were proposed to encode the common phloem proteins (P-proteins) that plug sieve plates after wounding. We carried out a comprehensive characterization of two tobacco (Nicotiana tabacum) SEO genes (NtSEO). Reporter genes controlled by the NtSEO promoters were expressed specifically in immature sieve elements, and GFP-SEO fusion proteins formed parietal agglomerates in intact sieve elements as well as sieve plate plugs after wounding. NtSEO proteins with and without fluorescent protein tags formed agglomerates similar in structure to native P-protein bodies when transiently coexpressed in Nicotiana benthamiana, and the analysis of these protein complexes by electron microscopy revealed ultrastructural features resembling those of native P-proteins. NtSEO-RNA interference lines were essentially devoid of P-protein structures and lost photoassimilates more rapidly after injury than control plants, thus confirming the role of P-proteins in sieve tube sealing. We therefore provide direct evidence that SEO genes in tobacco encode P-protein subunits that affect translocation. We also found that peptides recently identified in fascicular phloem P-protein plugs from squash (Cucurbita maxima) represent cucurbit members of the SEO family. Our results therefore suggest a common evolutionary origin for P-proteins found in the sieve elements of all dicotyledonous plants and demonstrate the exceptional status of extrafascicular P-proteins in cucurbits.
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Affiliation(s)
- Antonia M. Ernst
- Fraunhofer Institute for Molecular Biology and Applied Ecology, 48143 Münster, Germany
| | - Stephan B. Jekat
- Fraunhofer Institute for Molecular Biology and Applied Ecology, 48143 Münster, Germany
| | - Sascia Zielonka
- Fraunhofer Institute for Molecular Biology and Applied Ecology, 48143 Münster, Germany
| | - Boje Müller
- Fraunhofer Institute for Molecular Biology and Applied Ecology, 48143 Münster, Germany
| | - Ulla Neumann
- Max Planck Institute for Plant Breeding Research, 50829 Cologne, Germany
| | - Boris Rüping
- Institute of Plant Biology and Biotechnology, University of Muenster, 48143 Münster, Germany
| | - Richard M. Twyman
- Department of Biology, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Vladislav Krzyzanek
- Institute of Medical Physics and Biophysics, University of Muenster, 48149 Münster, Germany; and
- Institute of Scientific Instruments, Academy of Sciences of the Czech Republic, 61264 Brno, Czech Republic
| | - Dirk Prüfer
- Fraunhofer Institute for Molecular Biology and Applied Ecology, 48143 Münster, Germany
- Institute of Plant Biology and Biotechnology, University of Muenster, 48143 Münster, Germany
| | - Gundula A. Noll
- Institute of Plant Biology and Biotechnology, University of Muenster, 48143 Münster, Germany
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