On the Edge of Dispensability, the Chloroplast <i>ndh</i> Genes
The polypeptides encoded by the chloroplast <i>ndh</i> genes and some nuclear genes form the thylakoid NADH dehydrogenase (Ndh) complex, homologous to the mitochondrial complex I. Except for Charophyceae (algae related to higher plants) and a few Prasinophyceae, all eukaryotic algae lack...
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| Formato: | article |
| Lenguaje: | EN |
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MDPI AG
2021
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| Materias: | |
| Acceso en línea: | https://doaj.org/article/ecdcc56d79b74b7abca8221c9c593e45 |
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| Sumario: | The polypeptides encoded by the chloroplast <i>ndh</i> genes and some nuclear genes form the thylakoid NADH dehydrogenase (Ndh) complex, homologous to the mitochondrial complex I. Except for Charophyceae (algae related to higher plants) and a few Prasinophyceae, all eukaryotic algae lack <i>ndh</i> genes. Among vascular plants, the <i>ndh</i> genes are absent in epiphytic and in some species scattered among different genera, families, and orders. The recent identification of many plants lacking plastid <i>ndh</i> genes allows comparison on phylogenetic trees and functional investigations of the <i>ndh</i> genes. The <i>ndh</i> genes protect Angiosperms under various terrestrial stresses, maintaining efficient photosynthesis. On the edge of dispensability, <i>ndh</i> genes provide a test for the natural selection of photosynthesis-related genes in evolution. Variable evolutionary environments place Angiosperms without <i>ndh</i> genes at risk of extinction and, probably, most extant ones may have lost <i>ndh</i> genes recently. Therefore, they are evolutionary endpoints in phylogenetic trees. The low number of sequenced plastid DNA and the long lifespan of some Gymnosperms lacking <i>ndh</i> genes challenge models about the role of <i>ndh</i> genes protecting against stress and promoting leaf senescence. Additional DNA sequencing in Gymnosperms and investigations into the molecular mechanisms of their response to stress will provide a unified model of the evolutionary and functional consequences of the lack of <i>ndh</i> genes. |
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