Villaécija-Aguilar, JA, Körösy, C, Maisch, L et al. (6 more authors) (2022) KAI2 promotes Arabidopsis root hair elongation at low external phosphate by controlling local accumulation of AUX1 and PIN2. Current Biology, 32 (1). pp. 228-236. ISSN 0960-9822
Abstract
Root hair (RH) growth to increase the absorptive root surface area is a key adaptation of plants to limiting phosphate availability in soils. Despite the importance of this trait, especially for seedling survival, little is known about the molecular events connecting phosphate starvation sensing and RH growth regulation. KARRIKIN INSENSITIVE2 (KAI2), an α/β-hydrolase receptor of a yet-unknown plant hormone (“KAI2-ligand” [KL]), is required for RH elongation.1 KAI2 interacts with the F-box protein MORE AXILLIARY BRANCHING2 (MAX2) to target regulatory proteins of the SUPPRESSOR of MAX2 1 (SMAX1) family for degradation.2 Here, we demonstrate that Pi starvation increases KL signaling in Arabidopsis roots through transcriptional activation of KAI2 and MAX2. Both genes are required for RH elongation under these conditions, while smax1 smxl2 mutants have constitutively long RHs, even at high Pi availability. Attenuated RH elongation in kai2 mutants is explained by reduced shootward auxin transport from the root tip resulting in reduced auxin signaling in the RH zone, caused by an inability to increase localized accumulation of the auxin importer AUXIN TRANSPORTER PROTEIN1 (AUX1) and the auxin exporter PIN-FORMED2 (PIN2) upon Pi starvation. Consistent with AUX1 and PIN2 accumulation being mediated via ethylene signaling,3 expression of 1-AMINOCYCLOPROPANE-1-CARBOXYLATE SYNTHASE 7 (ACS7) is increased at low Pi in a KAI2-dependent manner, and treatment with an ethylene precursor restores RH elongation of acs7, but not of aux1 and pin2. Thus, KAI2 signaling is increased by phosphate starvation to trigger an ethylene- AUX1/PIN2-auxin cascade required for RH elongation.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2021 Elsevier Inc. This is an author produced version of an article published in Current Biology. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | Arabidopsis thaliana; AUX1; auxin; ethylene; KAI2; karrikin; PIN; root hairs; strigolactone |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Biological Sciences (Leeds) > School of Biology (Leeds) |
Funding Information: | Funder Grant number BBSRC (Biotechnology & Biological Sciences Research Council) BB/R00398X/1 |
Depositing User: | Symplectic Publications |
Date Deposited: | 15 Nov 2021 14:27 |
Last Modified: | 09 Nov 2022 01:29 |
Status: | Published |
Publisher: | Elsevier |
Identification Number: | 10.1016/j.cub.2021.10.044 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:180315 |
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