Term Information

Accession
PO:0000071
Name
companion cell
Ontology
plant_anatomy
Synonyms
célula acompañiante (Spanish, exact), minor vein companion cell (exact), 伴細胞 (Japanese, exact)
Alternate IDs
None
Definition
A parenchyma cell (PO:0000074) that is adjacent to a sieve tube element (PO:0000289) and arises from the same phloem mother cell (PO:0000400) as the sieve tube element. Source: PO_REF:00011
Comment
Companion cells are connected to sieve tube elements through plasmodesmata and function in phloem loading of small molecules, including photosynthate (either sucrose or raffinose-family oligosaccharides). May participate in phloem sucrose loading (GO:0009915). Molecules can be loaded into the companion cells from surrounding cells through either symplastic (via plasmodesmata) or apoplastic (transmembrane) transport. Unlike sieve tube elements, companion cells retain their nuclei and other organelles at maturity. A sieve tube element may have one or more or no companion cells associated with it. This term should not be used for other types of parenchyma cells (PO:0000074) that do not arise from the same phloem mother cell as a sieve tube element. Companion cells are found in angiosperms, as compared to albuminous cells (PO:0025412), which are found in non-angiosperm vascular plants. Companion cells may be specialized as transfer companion cells (PO:0025458), ordinary companion cells (PO:0025459), or intermediary companion cells (PO:0025460). Multiple types of companion cells may be found in the same plant.
Subset
CL
TraitNet
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Parents of companion cell (PO:0000071)
subject[Reorder by subject] relation[Reorder by relation] object[Reorder by object]
companion cell [RO:0002220 relation] RO:0002220  sieve tube element (PO:0000289)
companion cell [BFO:0000050 relation] BFO:0000050  phloem (PO:0005417)
companion cell [is_a relation] is_a  parenchyma cell (PO:0000074)
companion cell [is_a relation] is_a  independent continuant (BFO:0000004)
Children of companion cell (PO:0000071)
subject[Reorder by subject] relation[Reorder by relation] object[Reorder by object]
transfer companion cell (PO:0025458) [is_a relation] is_a  companion cell
ordinary companion cell (PO:0025459) [is_a relation] is_a  companion cell
intermediary companion cell (PO:0025460) [is_a relation] is_a  companion cell
PO_GIT
442