SMAX1/SMXL2 regulate root and root hair development downstream of KAI2-mediated signalling in Arabidopsis

Karrikins are smoke-derived compounds presumed to mimic endogenous signalling molecules (KAI2-ligand, KL), whose signalling pathway is closely related to that of strigolactones (SLs), important regulators of plant development. Both karrikins/KLs and SLs are perceived by closely related α/β hydrolase receptors (KAI2 and D14 respectively), and signalling through both receptors requires the F-box protein MAX2. Furthermore, both pathways trigger proteasome-mediated degradation of related SMAX1-LIKE (SMXL) proteins, to influence development. It has previously been suggested in multiple studies that SLs are important regulators of root and root hair development in Arabidopsis, but these conclusions are based on phenotypes observed in the non-specific max2 mutants and by use of racemic-GR24, a mixture of stereoisomers that activates both D14 and KAI2 signalling pathways. Here, we demonstrate that the majority of the effects on Arabidopsis root development previously attributed to SL signalling are actually mediated by the KAI2 signalling pathway. Using mutants defective in SL or KL synthesis and/or perception, we show that KAI2-mediated signalling alone regulates root hair density and root hair length as well as root skewing, straightness and diameter, while both KAI2 and D14 pathways regulate lateral root density and epidermal cell length. We test the key hypothesis that KAI2 signals by a non-canonical receptor-target mechanism in the context of root development. Our results provide no evidence for this, and we instead show that all effects of KAI2 in the root can be explained by canonical SMAX1/SMXL2 activity. However, we do find evidence for non-canonical GR24 ligand-receptor interactions in D14/KAI2-mediated root hair development. Overall, our results demonstrate that the KAI2 signalling pathway is an important new regulator of root hair and root development in Arabidopsis and lay an important basis for research into a molecular understanding of how very similar and partially overlapping hormone signalling pathways regulate different phenotypic outputs.

Medienart:

E-Artikel

Erscheinungsjahr:

2019

Erschienen:

2019

Enthalten in:

Zur Gesamtaufnahme - volume:15

Enthalten in:

PLoS genetics - 15(2019), 8 vom: 01. Aug., Seite e1008327

Sprache:

Englisch

Beteiligte Personen:

Villaécija-Aguilar, José Antonio [VerfasserIn]
Hamon-Josse, Maxime [VerfasserIn]
Carbonnel, Samy [VerfasserIn]
Kretschmar, Annika [VerfasserIn]
Schmidt, Christian [VerfasserIn]
Dawid, Corinna [VerfasserIn]
Bennett, Tom [VerfasserIn]
Gutjahr, Caroline [VerfasserIn]

Links:

Volltext

Themen:

Arabidopsis Proteins
EC 3.-
HTL protein, Arabidopsis
Hydrolases
Intracellular Signaling Peptides and Proteins
Journal Article
Plant Growth Regulators
Research Support, Non-U.S. Gov't
SMAX1 protein, Arabidopsis
SMXL2 protein, Arabidopsis

Anmerkungen:

Date Completed 07.01.2020

Date Revised 09.03.2020

published: Electronic-eCollection

Citation Status MEDLINE

doi:

10.1371/journal.pgen.1008327

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM300748507