Decarboxylation of indoleacetic acid illuminates its evolution into a plant hormone
- 1Institute of Experimental Botany, Czech Academy of Sciences
Abstract
The evolution of indoleacetic acid (IAA) into the plant hormone auxin remains unclear. Here, we compared IAA response and metabolism in land plants and their closest living relatives, the streptophyte algae, using chemical treatments, phytohormone profiling, and targeted and untargeted metabolomics. Streptophyte algae showed neither plant-like auxin responses nor canonical IAA metabolism. Here, we demonstrate IAA side-chain decarboxylation as a novel pathway of cellular IAA metabolism, operating in streptophyte algae and land plants alike. Decarboxylation also underpinned IAA's innate photolability and yielded cytotoxic intermediates, which also accumulated endogenously under simulated sunlight. Together, these findings establish IAA decarboxylation as a major, conserved metabolic pathway, and suggest that the metabolic constraints arising from IAA's instability and indirect cytotoxicity contributed to its adoption as a plant hormone.
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BibTeX
@misc{schmidt2026decarboxylation,
title = {{Decarboxylation of indoleacetic acid illuminates its evolution into a plant hormone}},
author = {V. Schmidt and P. I. Dobrev and V. Knirsch and K. Muller and B. Svobodova and J. Lacek and P. Marsik and S. Vosolsobe and Y. Coudert and R. Skokan and J. Petrasek},
howpublished = {bioRxiv},
year = {2026},
month = sep,
doi = {10.64898/2026.09.07.749952},
url = {https://www.biorxiv.org/content/10.64898/2026.09.07.749952v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Decarboxylation of indoleacetic acid illuminates its evolution into a plant hormone
AU - V. Schmidt
AU - P. I. Dobrev
AU - V. Knirsch
AU - K. Muller
AU - B. Svobodova
AU - J. Lacek
AU - P. Marsik
AU - S. Vosolsobe
AU - Y. Coudert
AU - R. Skokan
AU - J. Petrasek
PY - 2026
DA - 2026/09/07
PB - bioRxiv
DO - 10.64898/2026.09.07.749952
UR - https://www.biorxiv.org/content/10.64898/2026.09.07.749952v1
AB - The evolution of indoleacetic acid (IAA) into the plant hormone auxin remains unclear. Here, we compared IAA response and metabolism in land plants and their closest living relatives, the streptophyte algae, using chemical treatments, phytohormone profiling, and targeted and untargeted metabolomics. Streptophyte algae showed neither plant-like auxin responses nor canonical IAA metabolism. Here, we demonstrate IAA side-chain decarboxylation as a novel pathway of cellular IAA metabolism, operating in streptophyte algae and land plants alike. Decarboxylation also underpinned IAA's innate photolability and yielded cytotoxic intermediates, which also accumulated endogenously under simulated sunlight. Together, these findings establish IAA decarboxylation as a major, conserved metabolic pathway, and suggest that the metabolic constraints arising from IAA's instability and indirect cytotoxicity contributed to its adoption as a plant hormone.
ER -