Editing Chloroplast (section)

=== Green algal derived chloroplasts ===
[[Green algae]] have been taken up by many groups in three or four separate events.<ref name="Rogers-2007">{{cite journal | vauthors=Rogers MB, Gilson PR, Su V, McFadden GI, Keeling PJ | title=The complete chloroplast genome of the chlorarachniophyte Bigelowiella natans: evidence for independent origins of chlorarachniophyte and euglenid secondary endosymbionts | journal=Molecular Biology and Evolution | volume=24 | issue=1 | pages=54–62 | date=January 2007 | pmid=16990439 | doi=10.1093/molbev/msl129 | doi-access=free }}</ref> Primarily, secondary chloroplasts derived from green algae are in the [[euglenid]]s and [[chlorarachniophyte]]s. They are also found in one lineage of [[dinoflagellate]]s<ref name="Keeling-2010">{{cite journal | vauthors=Keeling PJ | title=The endosymbiotic origin, diversification and fate of plastids | journal=Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences | volume=365 | issue=1541 | pages=729–48 | date=March 2010 | pmid=20124341 | pmc=2817223 | doi=10.1098/rstb.2009.0103 }}</ref> and possibly the ancestor of the CASH lineage ([[cryptomonad]]s, [[Alveolata|alveolates]], [[stramenopile]]s and [[haptophyte]]s)<ref name="Moustafa-2009">{{cite journal | vauthors=Moustafa A, Beszteri B, Maier UG, Bowler C, Valentin K, Bhattacharya D | title=Genomic footprints of a cryptic plastid endosymbiosis in diatoms | journal=Science | volume=324 | issue=5935 | pages=1724–6 | date=June 2009 | pmid=19556510 | doi=10.1126/science.1172983 | url=https://epic.awi.de/id/eprint/20816/1/Mou2009a.pdf | bibcode=2009Sci...324.1724M | s2cid=11408339 }}</ref> Many green algal derived chloroplasts contain [[pyrenoid]]s, but unlike chloroplasts in their green algal ancestors, storage product collects in granules outside the chloroplast.<ref name="Kim-2009" />

==== Euglenophytes ====
{{See also|Euglenophyceae}}
[[File:Two Euglena.jpg|thumb|''[[Euglena]]'', a [[euglenophyte]], contains secondary chloroplasts from green algae.]]

The euglenophytes are a group of common [[flagellated]] [[protists]] that contain chloroplasts derived from a green alga.<ref name="Keeling-2004" /> Euglenophytes are the only group outside [[Diaphoretickes]] that have chloroplasts without performing [[kleptoplasty]].<ref>{{Cite journal |last1=Burki |first1=Fabien |last2=Roger |first2=Andrew J. |last3=Brown |first3=Matthew W. |last4=Simpson |first4=Alastair G.B. |date=2020-01-01 |title=The New Tree of Eukaryotes |url=https://linkinghub.elsevier.com/retrieve/pii/S0169534719302575 |journal=Trends in Ecology & Evolution |volume=35 |issue=1 |pages=43–55 |doi=10.1016/j.tree.2019.08.008 |pmid=31606140 |bibcode=2020TEcoE..35...43B |issn=0169-5347}}</ref><ref>{{Cite journal |last1=Sibbald |first1=Shannon J. |last2=Archibald |first2=John M. |date=2020-05-20 |title=Genomic Insights into Plastid Evolution |url=https://academic.oup.com/gbe/article/12/7/978/5836826 |journal=Genome Biology and Evolution |volume=12 |issue=7 |pages=978–990 |doi=10.1093/gbe/evaa096|pmid=32402068 |pmc=7348690 }}</ref> Euglenophyte chloroplasts have three membranes. It is thought that the membrane of the primary endosymbiont host was lost (e.g. the green algal membrane), leaving the two cyanobacterial membranes and the secondary host's phagosomal membrane.<ref name="Keeling-2004" /> Euglenophyte chloroplasts have a [[pyrenoid]] and [[thylakoid]]s stacked in groups of three. The carbon fixed through photosynthesis is stored in the form of [[paramylon]], which is contained in membrane-bound granules in the cytoplasm of the euglenophyte.<ref name="Kim-2009" /><ref name="Keeling-2010" />

==== Chlorarachniophytes ====
{{See also|Chlorarachniophyte}}
[[File:Chlorarachnion reptans.jpg|thumb|left|''[[Chlorarachnion reptans]]'' is a chlorarachniophyte. Chlorarachniophytes replaced their original [[red algal]] endosymbiont with a [[green alga]].]]

[[Chlorarachniophytes]] are a rare group of organisms that also contain chloroplasts derived from green algae,<ref name="Keeling-2004" /> though their story is more complicated than that of the euglenophytes. The ancestor of chlorarachniophytes is thought to have been a eukaryote with a ''red'' algal derived chloroplast. It is then thought to have lost its first red algal chloroplast, and later engulfed a green alga, giving it its second, green algal derived chloroplast.<ref name="Keeling-2010" />

Chlorarachniophyte chloroplasts are bounded by four membranes, except near the cell membrane, where the chloroplast membranes fuse into a double membrane.<ref name="Kim-2009" /> Their thylakoids are arranged in loose stacks of three.<ref name="Kim-2009" /> Chlorarachniophytes have a form of polysaccharide called [[chrysolaminarin]], which they store in the cytoplasm,<ref name="Keeling-2010" /> often collected around the chloroplast [[pyrenoid]], which bulges into the cytoplasm.<ref name="Kim-2009" />

Chlorarachniophyte chloroplasts are notable because the green alga they are derived from has not been completely broken down—its nucleus still persists as a [[nucleomorph]]<ref name="Keeling-2004" /> found between the second and third chloroplast membranes<ref name="Kim-2009" />—the [[periplastid space]], which corresponds to the green alga's cytoplasm.<ref name="Keeling-2010" />

==== Prasinophyte-derived chloroplast ====
{{See also|Lepidodinium}}
[[File:Lepidodinium chlorophorum 68163.jpg|thumb|left|Lepidodinium chlorophorum's green colour is caused by a plastid derived from [[Pedinophyceae]].]]

Dinoflagellates in the genus ''[[Lepidodinium]]'' have lost their original peridinin chloroplast and replaced it with a green algal derived chloroplast (more specifically, a [[prasinophyte]]).<ref name="Kim-2009" /><ref name="Hackett-2004" /> ''Lepidodinium'' is the only dinoflagellate that has a chloroplast that's not from the [[rhodoplast]] lineage. The chloroplast is surrounded by two membranes and has no nucleomorph—all the nucleomorph genes have been transferred to the dinophyte [[cell nucleus|nucleus]].<ref name="Hackett-2004" /> The endosymbiotic event that led to this chloroplast was serial secondary endosymbiosis rather than tertiary endosymbiosis—the endosymbiont was a [[green alga]] containing a primary chloroplast (making a secondary chloroplast).<ref name="Keeling-2010" />

==== Tripartite symbiosis ====
[[File:Abg4102.F1.large.jpg|thumb|left|Pseudoblepharisma tenue with its two photosynthetic symbionts.]]

The [[ciliate]] ''[[Pseudoblepharisma tenue]]'' has two bacterial symbionts, one pink, one green. In 2021, both symbionts were confirmed to be photosynthetic: Ca. ''[[Thiodictyon]] intracellulare'' ([[Chromatiaceae]]), a [[purple sulfur bacteria|purple sulfur bacterium]] with a genome just half the size of their closest known relatives; and ''[[Chlorella]]'' sp. K10, a green alga.<ref>{{cite journal | pmc=10063809 | date=2023 | last1=Christian | first1=R. | last2=Labbancz | first2=J. | last3=Usadel | first3=B. | last4=Dhingra | first4=A. | title=Understanding protein import in diverse non-green plastids | journal=Frontiers in Genetics | volume=14 | doi=10.3389/fgene.2023.969931 | doi-access=free | pmid=37007964 }}</ref> There is also a variant of ''Pseudoblepharisma tenue'' that only contains chloroplasts from green algae and no endosymbiotic purple bacteria.<ref name="Hines">{{cite journal |last1=Hines |first1=Hunter N. |last2=McCarthy |first2=Peter J. |last3=Esteban |first3=Genoveva F. |title=A Case Building Ciliate in the Genus Pseudoblepharisma Found in Subtropical Fresh Water |journal=Diversity |date=27 February 2022 |volume=14 |issue=3 |pages=174 |doi=10.3390/d14030174 |doi-access=free|bibcode=2022Diver..14..174H }}</ref>