Inactivation of the entire Arabidopsis group II GH3s confers tolerance to salinity and water deficit

Authors

Rubén Casanova-Sáez, Swedish University of Agricultural Sciences
Eduardo Mateo-Bonmatí, Swedish University of Agricultural Sciences
Jan Šimura, Swedish University of Agricultural Sciences
Aleš Pěnčík, Palacký University and Institute of Experimental Botany of the Czech Academy of Sciences
Ondřej Novák, Swedish University of Agricultural Sciences
Paul Staswick, University of Nebraska - LincolnFollow
Karin Ljung, Swedish University of Agricultural SciencesFollow

ORCID IDs

Rubén Casanova-Sáez https://orcid.org/0000-0001-5683-7051

Eduardo Mateo-Bonmatí https://orcid.org/0000-0002-2364-5173

Jan Šimura https://orcid.org/0000-0002-2364-5173

Aleš Pěnčík https://orcid.org/0000-0002-1314-2249

Ondřej Novák https://orcid.org/0000-0003-3452-0154

Paul Staswick https://orcid.org/0000-0003-2798-0275

Karin Ljung https://orcid.org/0000-0003-2901-189X

Date of this Version

2022

Citation

New Phytologist (2022) 235: 263–275

doi: 10.1111/nph.18114

Comments

This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License,

Abstract

Indole-3-acetic acid (IAA) controls a plethora of developmental processes. Thus, regulation of its concentration is of great relevance for plant performance. Cellular IAA concentration depends on its transport, biosynthesis and the various pathways for IAA inactivation, including oxidation and conjugation.

Group II members of the GRETCHEN HAGEN 3 (GH3) gene family code for acyl acid amido synthetases catalysing the conjugation of IAA to amino acids. However, the high degree of functional redundancy among them has hampered thorough analysis of their roles in plant development.

In this work, we generated an Arabidopsis gh3.1,2,3,4,5,6,9,17 (gh3oct) mutant to knock out the group II GH3 pathway. The gh3oct plants had an elaborated root architecture, showed an increased tolerance to different osmotic stresses, including an IAA-dependent tolerance to salinity, and were more tolerant to water deficit. Indole-3-acetic acid metabolite quantification in gh3oct plants suggested the existence of additional GH3-like enzymes in IAA metabolism. Moreover, our data suggested that 2-oxindole-3-acetic acid production depends, at least in part, on the GH3 pathway. Targeted stress-hormone analysis further suggested involvement of abscisic acid in the differential response to salinity of gh3oct plants.

Taken together, our data provide new insights into the roles of group II GH3s in IAA metabolism and hormone-regulated plant development.