Editing Respiratory complex I (section)

== In chloroplasts ==
A proton-pumping, ubiquinone-using NADH dehydrogenase complex, homologous to complex I, is found in the chloroplast genomes of most [[land plant]]s under the name ''ndh''. This complex is inherited from the original symbiosis from cyanobacteria, but has been lost in most eukaryotic algae, some [[gymnosperm]]s (''Pinus'' and [[gnetophytes]]), and some very young lineages of [[angiosperm]]s. The purpose of this complex is originally cryptic as chloroplasts do not participate in respiration, but now it is known that ''ndh'' serves to maintain photosynthesis in stressful situations. This makes it at least partially dispensable in favorable conditions. It is evident that angiosperm lineages without ''ndh'' do not last long from their young ages, but how gymnosperms survive on land without ''ndh'' for so long is unknown.<ref>{{cite journal |last1=Sabater |first1=B |title=On the Edge of Dispensability, the Chloroplast ''ndh'' Genes. |journal=International Journal of Molecular Sciences |date=19 November 2021 |volume=22 |issue=22 |page=12505 |doi=10.3390/ijms222212505 |pmid=34830386 |pmc=8621559 |doi-access=free}}</ref>