| Archaeplastida Fossil range: Mesoproterozoic - Recent |
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 Indian paintbrush and wild huckleberry
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The Archaeplastida or Primoplantae are a major line of eukaryotes, comprising the land plants, green and red algae, and a small group called the glaucophytes. Year 2005 ( MMV) was a Common year starting on Saturday (link displays full calendar of the Gregorian calendar. Plants are living Organisms belonging to the kingdom Plantae. Chlorophyta, a division of Green algae, of mostly aquatic Photosynthetic Eukaryotic organisms The Charophyta are a division of Green algae, including the closest relatives of the Embryophyte plants The embryophytes are the most familiar group of Plants They include Trees Flowers Ferns Mosses and various other green The red algae (Rhodophyta ˌroʊdəˈfaɪtə roʊˈdɒfɨtə from Greek: ῥόδον (rhodon = rose + φυτόν (phyton = plant thus red plant are The glaucophytes, also known as glaucocystophytes or glaucocystids, are a small group of freshwater microscopic Algae. Animals Plants fungi, and Protists are eukaryotes (juːˈkærɪɒt or -oʊt Organisms whose cells are organized into complex The embryophytes are the most familiar group of Plants They include Trees Flowers Ferns Mosses and various other green The green algae (singular green alga) are the large group of Algae from which the Embryophytes (higher plants emerged The red algae (Rhodophyta ˌroʊdəˈfaɪtə roʊˈdɒfɨtə from Greek: ῥόδον (rhodon = rose + φυτόν (phyton = plant thus red plant are The glaucophytes, also known as glaucocystophytes or glaucocystids, are a small group of freshwater microscopic Algae. All of these organisms have plastids surrounded by two membranes, suggesting they developed directly from endosymbiotic cyanobacteria. Plastids are major Organelles found in plants and algae Plastids often contain pigments used in photosynthesis and the types of pigments present can change Cyanobacteria, also known as blue-green algae, blue-green bacteria or Cyanophyta, is a phylum of Bacteria that obtain their energy In all other groups, plastids are surrounded by three or four membranes, and were acquired secondarily from green or red algae.
The cells typically lack centrioles and have mitochondria with flat cristae. A Centriole is a barrel shaped Organelle found in most animal Eukaryotic cells though absent in Higher plants and Fungi. In Cell biology, a mitochondrion (plural mitochondria) is a membrane-enclosed Organelle found in most eukaryotic cells. There is usually a cell wall including cellulose, and food is stored in the form of starch. A cell wall is a tough flexible and sometimes fairly rigid layer surrounding a cell, located external to the Cell membrane, which provides the cell with structural Cellulose is an Organic compound with the formula, a Polysaccharide consisting of a linear chain of several hundred to over ten thousand β(1→4 Starch, CAS # 9005-25-8 Chemical formula (C6H10O5n is a Polysaccharide However, these characters are also shared with other eukaryotes. The main evidence the Archaeplastida form a monophyletic group comes from genetic studies, which indicate that plastids probably had a single origin. A clade is a taxonomic group comprising a single Common ancestor and all the descendants of that ancestor
The archaeplastids fall in two main evolutionary lines. The red algae are pigmented with chlorophyll a and phycobiliproteins, like most cyanobacteria. Chlorophyll is a green Pigment found in most Plants Algae and Cyanobacteria. Phycobiliproteins are water-soluble Proteins present in Cyanobacteria and certain algae ( Rhodophytes cryptomonads, Glaucocystophytes The green algae and land plants (together known as Viridiplantae, Latin for "green plants") are pigmented with chlorophylls a and b, but lack phycobiliproteins. Plants are living Organisms belonging to the kingdom Plantae. The positions of the glaucophytes are uncertain; they have the typical cyanobacterial pigments, and are unusual in retaining a cell wall within the plastids (called cyanelles).
Cavalier-Smith (1981)[1] suggested that the kingdom Plantae should refer to this group, and accordingly it may be called the Plantae sensu lato, but other versions of the kingdom are still in common use. Professor Thomas (Tom Cavalier-Smith (born October 21 1942) FRS, FRSC, NERC Professorial Fellow is a Professor of Plants are living Organisms belonging to the kingdom Plantae. Sensu is a Latin term meaning "in the sense of"It is used in fields including biology geology and law in the phrases sensu stricto The more precise name Archaeplastida was introduced by Adl et al. (2005). [2] Another name for the same clade, published in Palmer et al. (2004), is Primoplantae. [3]
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Taxonomic history
Some authors have simply referred to this group as plants or Plantae. [4] [5] Since the same name has also been applied to less inclusive clades, such as Viridiplantae and embryophytes, this larger group is sometimes known as Plantae sensu lato ("plants in the broad sense"). A clade is a taxonomic group comprising a single Common ancestor and all the descendants of that ancestor Plants are living Organisms belonging to the kingdom Plantae. The embryophytes are the most familiar group of Plants They include Trees Flowers Ferns Mosses and various other green
Because the name Plantae is ambiguous, other names have been proposed. Primoplantae, which appeared in 2004, seems to be the first new name suggested for this group. [6]
Another name that has been applied to this node is Plastida, defined as the clade sharing "plastids of primary (direct prokaryote) origin in Magnolia virginiana Linnaeus 1753". The Sweetbay magnolia ( Magnolia virginiana) also called just Sweetbay is a member of the Magnolia family Magnoliaceae. [7]
Most recently, the name Archaeplastida was proposed. [8]
Morphology
All archaeplastids have plastids called chloroplasts that carry out photosynthesis, derived from captured cyanobacteria. Plastids are major Organelles found in plants and algae Plastids often contain pigments used in photosynthesis and the types of pigments present can change In glaucophytes, perhaps the most primitive members of the group, the chloroplast is called a cyanelle and shares several features with cyanobacteria, including a peptidoglycan cell wall, that are not retained in other primoplants. The resemblance of cyanelles to cyanobacteria supports the endosymbiotic theory. The endosymbiotic theory concerns the origins of mitochondria and Plastids (e
Archaeplastids vary widely in the degree of their cell organization, from isolated cells to filaments to colonies to multi-celled organisms. The earliest primoplants were unicellular, and many groups remain so today. Multicelluarity evolved separately in several groups, including red algae, ulvophyte green algae, and in the green algae that gave rise to stoneworts and land plants. The Ulvophyceae or Ulvophytes are class of Green algae The Charales are Algae in the division Charophyta. They are green plants believed to be the closest relatives of the green land plants. The cells of most archaeplastids have walls, commonly but not always made of cellulose.
Endosymbiosis
Because the ancestral archaeplastid acquired its chloroplasts directly by engulfing cyanobacteria, the event is known as a primary endosymbiosis. The endosymbiotic theory concerns the origins of mitochondria and Plastids (e Evidence for this includes the presence of a double membrane around the chloroplasts; one membrane belonged to the bacterium, and the other to the eukaryote that captured it. Over time, many genes from the chloroplast have been transferred to the nucleus of the host cell. The presence of such genes in the nuclei of eukaryotes without chloroplasts suggests this transfer happened early in the primoplants' evolution. [9]
All other eukaryotes with chloroplasts gained them by engulfing a single-celled archaeplastid with its own bacterially-derived chloroplasts. The chloroplasts of euglenids and chlorarachniophytes appear to be captured green algae. The euglenids (or euglenoids) are one of the best-known groups of Flagellates commonly found in freshwater especially when it is rich in organic materials with a Chlorarachniophytes are a small group of Algae occasionally found in tropical oceans Other photosynthetic eukaryotes have chloroplasts that are captured (primoplant) red algae, and include heterokont algae, cryptophytes, haptophytes, and dinoflagellates. The heterokonts or stramenopiles are a major line of Eukaryotes presently containing about 10500 known species The haptophytes, classed either as the Prymnesiophyta or Haptophyta are a Phylum of Algae The Chloroplasts are pigmented similarly to those of the The dinoflagellates are a large group of Flagellate Protists Most are marine Plankton, but Because these involve endosymbiosis of cells that have their own endosymbionts, the process is called secondary endosymbiosis. The chloroplasts of these eukaryotes are typically surrounded by more than two membranes, reflecting their history of multiple engulfment.
Fossil record
Perhaps the most ancient remains of Archaeplastida are microfossils from the Roper group in northern Australia. Micropaleontology (also sometimes spelled as micropalaeontology) is that branch of Paleontology which studies microfossils The structure of these single-celled fossils resemble that of modern green algae. These date to the Mesoproterozoic Era, about 1500 to 1300 Ma (million years ago) [10] These fossils are consistent with a molecular clock study that calculated that this clade diverged about 1500 Ma. The Mesoproterozoic Era is a geologic era that occurred between 1600 Ma and 1000 Ma (million years ago Annum is one form of the Latin noun meaning Year, not a form normally used for derivatives in modern languages the accusative singular The molecular clock (based on the molecular clock hypothesis ( MCH) is a technique in Molecular evolution to relate the divergence time of two Species [11] The oldest fossil that can be assigned to a specific modern group is the red alga Bangiomorpha, from 1200 Ma. The red algae (Rhodophyta ˌroʊdəˈfaɪtə roʊˈdɒfɨtə from Greek: ῥόδον (rhodon = rose + φυτόν (phyton = plant thus red plant are [12]
In the late Neoproterozoic Era, algal fossils became more numerous and diverse. The Neoproterozoic Era is the unit of geologic time from 1000 to 542 +/- 0 Eventually, in the Paleozoic Era, plants emerged onto land, and have continued to flourish up to the present. The Paleozoic or Palaeozoic Era (from the Greek palaio (παλαιο "old" and zoe (ζωη "life" meaning "ancient life"
References
- ^ T. Cavalier-Smith (1981). "Eukaryote Kingdoms: Seven or Nine?". BioSystems 14: 461–481. doi:. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.
- ^ Sina M. Adl et al (2005). "The New Higher Level Classification of Eukaryotes with Emphasis on the Taxonomy of Protists". Journal of Eukaryotic Microbiology 52 (5): 399. doi:. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.
- ^ Palmer, Jeffrey D. ; Soltis, Douglas E. ; & Chase, Mark W. (2004). "The plant tree of life: an overview and some points of view". American Journal of Botany 91: 1437–1445. doi:. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.
- ^ Cavalier-Smith, Thomas (1981). Professor Thomas (Tom Cavalier-Smith (born October 21 1942) FRS, FRSC, NERC Professorial Fellow is a Professor of "Eukaryote Kingdoms: Seven or Nine?". BioSystems 14 (3-4): 461–481. doi:. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.
- ^ Bhattacharya, Debashish; Yoon, Hwan Su; Hackett, Jeremiah (2003). "Photosynthetic eukaryotes unite: endosymbiosis connects the dots". BioEssays 26: 50–60. doi:. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.
- ^ Palmer, Jeffrey D. (2004). "The plant tree of life: an overview and some points of view". American Journal of Botany 91 (10): 1437–1445. doi:. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.
- ^ Simpson, A. G. B. (2004). "{{{title}}}". First International Phylogenetic Nomenclature Meeting. Paris, July 6-9, 2004. .
- ^ Adl, Sina M. ; et al (2005). "The New Higher Level Classification of Eukaryotes with Emphasis on the Taxonomy of Protists". Journal of Eukaryotic Microbiology 52 (5): 399. doi:. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.
- ^ Andersson, Jan O. ; & Roger, Andrew J. (2002). "A cyanobacterial gene in non-photosynthetic protists--An early chloroplast acquisition in eukaryotes?". Current Biology 12 (2): 115–119. . doi:. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document. ISSN 0960-9822. An International Standard Serial Number ( ISSN) is a unique eight-digit number used to identify a print or electronic Periodical publication.
- ^ Javaux, Emmanuelle J; Knoll, Andrew H, & Walter, Malcolm R. (2004). "TEM evidence for eukaryotic diversity in mid-Proterozoic oceans". Geobiology 2 (3): 121–132. doi:. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document. ISSN 1472-4677. An International Standard Serial Number ( ISSN) is a unique eight-digit number used to identify a print or electronic Periodical publication.
- ^ Yoon, Hwan Su; Hackett, Jeremiah D. , Ciniglia, Claudia; Pinto, Gabriele; & Bhattacharya, Debashish} (2004). "A molecular timeline for the origin of photosynthetic eukaryotes. ". Molecular Biology & Evolution 21 (5): 809-818. doi:. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document. ISSN 0737-4038. An International Standard Serial Number ( ISSN) is a unique eight-digit number used to identify a print or electronic Periodical publication.
- ^ Butterfield, Nicholas J. (2000). "Bangiomorpha pubescens n. gen. , n. sp. : implications for the evolution of sex, multicellularity, and the Mesoproterozoic/Neoproterozoic radiation of eukaryotes. ". Paleobiology 26 (3): 386–404. doi:. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document. ISSN 0094-8373. An International Standard Serial Number ( ISSN) is a unique eight-digit number used to identify a print or electronic Periodical publication.
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