The Interplay between Enucleated Sieve Elements and Companion Cells
In order to adapt to sessile life and terrestrial environments, vascular plants have developed highly sophisticated cells to transport photosynthetic products and developmental signals. Of these, two distinct cell types (i.e., the sieve element (SE) and companion cell) are arranged in precise positi...
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| Format: | Article |
| Language: | English |
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MDPI AG
2023-08-01
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| Series: | Plants |
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| Online Access: | https://www.mdpi.com/2223-7747/12/17/3033 |
| _version_ | 1797581961851568128 |
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| author | Angel J. Matilla |
| author_facet | Angel J. Matilla |
| author_sort | Angel J. Matilla |
| collection | DOAJ |
| description | In order to adapt to sessile life and terrestrial environments, vascular plants have developed highly sophisticated cells to transport photosynthetic products and developmental signals. Of these, two distinct cell types (i.e., the sieve element (SE) and companion cell) are arranged in precise positions, thus ensuring effective transport. During SE differentiation, most of the cellular components are heavily modified or even eliminated. This peculiar differentiation implies the selective disintegration of the nucleus (i.e., enucleation) and the loss of cellular translational capacity. However, some cellular components necessary for transport (e.g., plasmalemma) are retained and specific phloem proteins (P-proteins) appear. Likewise, MYB (i.e., <i>APL</i>) and NAC (i.e., <i>NAC45</i> and <i>NAC86</i>) transcription factors (TFs) and OCTOPUS proteins play a notable role in SE differentiation. The maturing SEs become heavily dependent on neighboring non-conducting companion cells, to which they are connected by plasmodesmata through which only 20–70 kDa compounds seem to be able to pass. The study of sieve tube proteins still has many gaps. However, the development of a protocol to isolate proteins that are free from any contaminating proteins has constituted an important advance. This review considers the very detailed current state of knowledge of both bound and soluble sap proteins, as well as the role played by the companion cells in their presence. Phloem proteins travel long distances by combining two modes: non-selective transport via bulk flow and selective regulated movement. One of the goals of this study is to discover how the protein content of the sieve tube is controlled. The majority of questions and approaches about the heterogeneity of phloem sap will be clarified once the morphology and physiology of the plasmodesmata have been investigated in depth. Finally, the retention of specific proteins inside an SE is an aspect that should not be forgotten. |
| first_indexed | 2024-03-10T23:15:05Z |
| format | Article |
| id | doaj.art-225bc20f9c874afdb3923ce5b4e662ea |
| institution | Directory Open Access Journal |
| issn | 2223-7747 |
| language | English |
| last_indexed | 2024-03-10T23:15:05Z |
| publishDate | 2023-08-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Plants |
| spelling | doaj.art-225bc20f9c874afdb3923ce5b4e662ea2023-11-19T08:40:21ZengMDPI AGPlants2223-77472023-08-011217303310.3390/plants12173033The Interplay between Enucleated Sieve Elements and Companion CellsAngel J. Matilla0Departamento de Biología Funcional, Universidad de Santiago de Compostela, 14971-Santiago de Compostela, SpainIn order to adapt to sessile life and terrestrial environments, vascular plants have developed highly sophisticated cells to transport photosynthetic products and developmental signals. Of these, two distinct cell types (i.e., the sieve element (SE) and companion cell) are arranged in precise positions, thus ensuring effective transport. During SE differentiation, most of the cellular components are heavily modified or even eliminated. This peculiar differentiation implies the selective disintegration of the nucleus (i.e., enucleation) and the loss of cellular translational capacity. However, some cellular components necessary for transport (e.g., plasmalemma) are retained and specific phloem proteins (P-proteins) appear. Likewise, MYB (i.e., <i>APL</i>) and NAC (i.e., <i>NAC45</i> and <i>NAC86</i>) transcription factors (TFs) and OCTOPUS proteins play a notable role in SE differentiation. The maturing SEs become heavily dependent on neighboring non-conducting companion cells, to which they are connected by plasmodesmata through which only 20–70 kDa compounds seem to be able to pass. The study of sieve tube proteins still has many gaps. However, the development of a protocol to isolate proteins that are free from any contaminating proteins has constituted an important advance. This review considers the very detailed current state of knowledge of both bound and soluble sap proteins, as well as the role played by the companion cells in their presence. Phloem proteins travel long distances by combining two modes: non-selective transport via bulk flow and selective regulated movement. One of the goals of this study is to discover how the protein content of the sieve tube is controlled. The majority of questions and approaches about the heterogeneity of phloem sap will be clarified once the morphology and physiology of the plasmodesmata have been investigated in depth. Finally, the retention of specific proteins inside an SE is an aspect that should not be forgotten.https://www.mdpi.com/2223-7747/12/17/3033sieve elementsapenucleationcompanion cellendoplasmic reticulumtranscription factors |
| spellingShingle | Angel J. Matilla The Interplay between Enucleated Sieve Elements and Companion Cells Plants sieve element sap enucleation companion cell endoplasmic reticulum transcription factors |
| title | The Interplay between Enucleated Sieve Elements and Companion Cells |
| title_full | The Interplay between Enucleated Sieve Elements and Companion Cells |
| title_fullStr | The Interplay between Enucleated Sieve Elements and Companion Cells |
| title_full_unstemmed | The Interplay between Enucleated Sieve Elements and Companion Cells |
| title_short | The Interplay between Enucleated Sieve Elements and Companion Cells |
| title_sort | interplay between enucleated sieve elements and companion cells |
| topic | sieve element sap enucleation companion cell endoplasmic reticulum transcription factors |
| url | https://www.mdpi.com/2223-7747/12/17/3033 |
| work_keys_str_mv | AT angeljmatilla theinterplaybetweenenucleatedsieveelementsandcompanioncells AT angeljmatilla interplaybetweenenucleatedsieveelementsandcompanioncells |