The amphibious plant Rorippa aquatica produces markedly different leaves on land and underwater. A 2024 Communications Biology study built a chromosome-level genome and used transcriptomics and hormone/light experiments to investigate submergence-induced heterophylly.
A rearranged allotetraploid genome
R. aquatica has 2n=30 chromosomes. Comparative genomics and chromosome painting support an allotetraploid origin followed by chromosome rearrangements.
Transcriptomic response starts quickly
RNA-seq detected strong expression changes after only one hour of submergence. Leaf-margin incisions became visibly deeper by day 4 and were more pronounced by day 7.
Ethylene drives the submerged-leaf program
Applying the ethylene precursor ACC on land induced narrower submerged-like leaves, while inhibiting ethylene responses with AgNO3 suppressed the underwater morphology. Ethylene signaling is therefore a central pathway in the submergence response.
Blue light attenuates ethylene signaling
Blue light weakened the ethylene/submergence response, but the experiment does not establish a simple one-step “blue light switches leaves back to terrestrial form” mechanism. ABA and gibberellin pathways also contribute, and temperature-responsive heterophylly may operate partly in parallel.
The system offers insight into flood adaptation, but the study does not yet demonstrate transfer of this leaf-plasticity mechanism into crop yield protection.
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Reference
- Sakamoto T et al. A chromosome-level genome assembly for the amphibious plant Rorippa aquatica reveals its allotetraploid origin and mechanisms of heterophylly upon submergence. Communications Biology. 2024;7:431. https://doi.org/10.1038/s42003-024-06088-7
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