Seagrasses show ongoing loss of ethylene biosynthesis genes through pseudogene evidence
Researchers identified pseudogenes in seagrass genomes that confirm the loss of genes involved in ethylene biosynthesis, an adaptation to aquatic life. The study found that some seagrass species have completely lost these genes in the distant past, while others show evidence of recent, ongoing gene loss. This genetic adaptation appears linked to a submerged lifestyle rather than marine conditions specifically.
A bioRxiv preprint reports that seagrasses have undergone significant contraction of ACO and ACS genes—key players in ethylene biosynthesis—as part of their evolutionary transition from terrestrial to aquatic environments. By analyzing pseudogenes (non-functional gene remnants) across four seagrass species, researchers found that some species show traces of ancient gene loss with no pseudogenes remaining, while others display multiple pseudogenes indicating recent and potentially ongoing contraction. The same pattern of reduced ACO and ACS genes was observed in Utricularia gibba, a submerged freshwater plant, whereas two terrestrial species closely related to seagrasses retained higher numbers of these genes with no clear evidence of loss. The findings suggest that loss of ethylene biosynthesis is a genuine adaptation to submerged aquatic life rather than specifically to marine conditions, representing one of the most striking genomic contractions observed in flowering plants that have adopted aquatic lifestyles.
What's missing
The study does not discuss the functional consequences of ethylene loss for seagrass physiology, development, or stress responses, nor does it explain why ethylene biosynthesis would be disadvantageous or unnecessary in submerged environments. The evolutionary timeline and rate of gene loss are not quantified. The study's own limitations regarding sample size (four seagrass species) and the inference of ongoing loss from pseudogene presence alone are not explicitly addressed.
What different sources said
- bioRxivCenter
Pseudogenes confirm ongoing loss of ethylene biosynthesis in seagrasses
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