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bioRxiv · 10.64898/2026.06.02.729393

CONSERVATION AND DIVERGENCE WITHIN THE ARABIDOPSIS TPL/TPR COREPRESSOR FAMILY

Downing, B. L. R.·Pattichis, M.·Vaistij, F. E.·Farawila, M.·Ghannam, E.·Nguyen, L.·Denby, K.·Leydon, A.·Nemhauser, J.
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Abstract

The TOPLESS (TPL) and TOPLESS-RELATED (TPR1-TPR4) corepressors, collectively the Arabidopsis TPX family, are recruited by client proteins to regulate nearly every major plant regulatory program. Here, we dissect the conservation and divergence between paralogs using a combination of higher-order genetics, transcriptomics, and a synthetic repression assay. TPL, TPR1, and TPR4 were found to act as the primary repressors for many pathways, while TPR2 and TPR3 played a lesser or sometimes opposite regulatory role. Natural variation in the EAR-binding pocket subdivided the family into three subtypes: TPL/TPR1, TPR2/TPR3 and TPR4, and this variation at least partially explained observed differences between mutant phenotypes. In addition, cell-type-specific expression of EAR-containing effectors were used to tune root architecture, providing a possible route to engineering other TPX-regulated pathways. These results suggest a model where the TPX family balances robustness under stable conditions with the need for flexibility during cell fate transitions or stress responses.

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Downing, B. L. R., Pattichis, M., Vaistij, F. E., Farawila, M., Ghannam, E., Nguyen, L., Denby, K., Leydon, A., Nemhauser, J.. 2026-06-06. CONSERVATION AND DIVERGENCE WITHIN THE ARABIDOPSIS TPL/TPR COREPRESSOR FAMILY. https://doi.org/10.64898/2026.06.02.729393

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