ORIGINAL RESEARCH article
Front. Plant Sci.
Sec. Plant Metabolism and Chemodiversity
This article is part of the Research TopicRegulation and Sensing of Amino Acid Metabolism in PlantsView all articles
Genetic suppressor of fd-gogat1 reveals crosstalk among brassinosteroids, photorespiration, and amino acid metabolism
Provisionally accepted
Katherine A. KlimpelAnnika FindlaySannidhi MenonLeah Cytron-WalkerMichela CadarsoMeghan F. McGuireJeff PietroskeDaniel Idowu
Michael Busche
Jacob O. Brunkard*- University of Wisconsin-Madison, Madison, United States
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A classical forward genetic screen for Arabidopsis mutants with altered morphology identified a pleiotropic mutant, orbiculata (orb1), that has phenotypes including rounded leaves, chlorosis, and reduced growth. orb1 mapped to one of the Arabidopsis genes that encodes glutamate synthase, fd-gogat1 (ferredoxin-dependent glutamine oxoglutarate aminotransferase or Fd-GOGAT). To discover why this glutamate synthase impacts development, we conducted a forward genetic screen for suppressors of orb1. In the primary mutagenized generation, we identified a dominant mutant, which we call Lettuce, that rescues orb1 chlorosis but causes new pleiotropic defects that closely resemble the classical Arabidopsis cabbage and dwarf mutants that are defective in brassinosteroid or gibberellin signaling. Here, we take a chemical genetic approach to phenocopy Lettuce and investigate how gibberellins and brassinosteroids impact the development and physiology of fd-gogat1. We found that inhibiting brassinosteroid synthesis significantly increases chlorophyll content in fd-gogat1, which is chlorotic due to defects in the photorespiratory pathway. This discovery highlights how crosstalk among phytohormones (brassinosteroids) and core metabolic processes (amino acid biosynthesis and photorespiration) converge to regulate plant development and physiology.
Keywords: Glutamate Synthase, photorespiration, gibberellin, brassinosteroid, plant hormones, Plant metabolism, Plant genetics
Received: 06 Aug 2025; Accepted: 31 Oct 2025.
Copyright: © 2025 Klimpel, Findlay, Menon, Cytron-Walker, Cadarso, McGuire, Pietroske, Idowu, Busche and Brunkard. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Jacob O. Brunkard, brunkard@wisc.edu
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