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bioRxiv · 10.1101/2024.06.26.600793

Ethylene Receptor Gain- and Loss-of-function Mutants Reveal an ETR1-dependent Transcriptional Network in Roots

Harkey, A. F.·Khoury, M. G.·Muhlemann, J. K.·Olex, A. L.·Houben, M.·Binder, B.·Muday, G. K.
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Abstract

In Arabidopsis, a family of five receptors mediates ethylene responses in roots, with Ethylene Response 1 (ETR1) controlling increases in root hair proliferation and decreases in lateral root formation. To define the ETR1-dependent gene regulatory network (GRN) controlling root development, we profiled the root transcriptome from Col-0 and the etr1-3 gain-of-function and etr1-7 loss-of-function mutants in the presence and absence of ethylene or the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC). We identified 4,522 differentially expressed (DE) transcripts in Col-0 roots with altered abundance in response to ethylene and/or ACC treatment, with larger magnitude changes induced by ethylene. These included 553 DE transcripts that were ETR1 dependent, defined by a lack of response to treatment with ethylene and/or ACC in ethylene-insensitive etr1-3 and constitutively altered in etr1-7 in the presence and absence of treatment relative to time-0 Col-0. Within these ETR1-dependent transcripts were ethylene biosynthesis genes and transcription factors. ACC OXIDASE 2 (ACO2) and ACO3 convert ACC to ethylene and were ETR1-dependent, and ACO-promoter-driven reporter fusions were ACC regulated in root tissues in appropriate locations to control root development, with ACO5 localized to root hairs. Abundance of ETR1-dependent transcripts that were predicted to encode transcription factors and ACOs were examined in Col-0 and an ein3eil1 mutant with and without ACC treatment, suggesting the ETR1 and EIN3/EIL1 canonical ethylene signaling pathway regulated some, but not all, of these transcriptional responses. Together, these findings reveal features of an ETR1-dependent GRN that controls both ethylene synthesis and root growth and development. One sentence summaryTranscriptional responses in etr1 LOF and GOF mutants reveal an ethylene-mediated ETR1- and EIN3 dependent gene regulatory network that modulates ethylene signaling and synthesis and root development.

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Harkey, A. F., Khoury, M. G., Muhlemann, J. K., Olex, A. L., Houben, M., Binder, B., Muday, G. K.. 2024-06-26. Ethylene Receptor Gain- and Loss-of-function Mutants Reveal an ETR1-dependent Transcriptional Network in Roots. https://doi.org/10.1101/2024.06.26.600793

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