Overaccumulation of γ-Glutamylcysteine in a Jasmonate-Hypersensitive Arabidopsis Mutant Causes Jasmonate-Dependent Growth Inhibition.
Glutathione (GSH) is essential for many aspects of plant biology and is associated with jasmonate signaling in stress responses. We characterized an Arabidopsis (Arabidopsis thaliana) jasmonate-hypersensitive mutant (jah2) with seedling root growth 100-fold more sensitive to inhibition by the hormone jasmonyl-isoleucine than the wild type. Genetic mapping and genome sequencing determined that the mutation is in intron 6 of GLUTATHIONE SYNTHETASE2, encoding the enzyme that converts γ-glutamylcysteine (γ-EC) to GSH. The level of GSH in jah2 was 71% of the wild type, while the phytoalexin-deficient2-1 (pad2-1) mutant, defective in GSH1 and having only 27% of wild-type GSH level, was not jasmonate hypersensitive. Growth defects for jah2, but not pad2, were also seen in plants grown to maturity. Surprisingly, all phenotypes in the jah2 pad2-1 double mutant were weaker than in jah2. Quantification of γ-EC indicated these defects result from hyperaccumulation of this GSH precursor by 294- and 65-fold in jah2 and the double mutant, respectively. γ-EC reportedly partially substitutes for loss of GSH, but growth inhibition seen here was likely not due to an excess of total glutathione plus γ-EC because their sum in jah2 pad2-1 was only 16% greater than in the wild type. Further, the jah2 phenotypes were lost in a jasmonic acid biosynthesis mutant background, indicating the effect of γ-EC is mediated through jasmonate signaling and not as a direct result of perturbed redox status.
Department of Agronomy and Horticulture, University of Nebraska, Lincoln, Nebraska 68583 (H.-H.W., M.R., P.S.);Center for Biotechnology (J.-J.M.R.), and Department of Biochemistry (R.G., J.A.), University of Nebraska, Lincoln, Nebraska 68588; andRiken Plant Science Center, Yokohama 230-0045, Japan (Y.J.).
Hsin-Ho
HH
Wei
Department of Agronomy and Horticulture, University of Nebraska, Lincoln, Nebraska 68583 (H.-H.W., M.R., P.S.);Center for Biotechnology (J.-J.M.R.), and Department of Biochemistry (R.G., J.A.), University of Nebraska, Lincoln, Nebraska 68588; andRiken Plant Science Center, Yokohama 230-0045, Japan (Y.J.).
Martha
M
Rowe
Department of Agronomy and Horticulture, University of Nebraska, Lincoln, Nebraska 68583 (H.-H.W., M.R., P.S.);Center for Biotechnology (J.-J.M.R.), and Department of Biochemistry (R.G., J.A.), University of Nebraska, Lincoln, Nebraska 68588; andRiken Plant Science Center, Yokohama 230-0045, Japan (Y.J.).
Jean-Jack M
http://orcid.org/0000-0002-2709-7880
JJ
Riethoven
Department of Agronomy and Horticulture, University of Nebraska, Lincoln, Nebraska 68583 (H.-H.W., M.R., P.S.);Center for Biotechnology (J.-J.M.R.), and Department of Biochemistry (R.G., J.A.), University of Nebraska, Lincoln, Nebraska 68588; andRiken Plant Science Center, Yokohama 230-0045, Japan (Y.J.).
Ryan
R
Grove
Department of Agronomy and Horticulture, University of Nebraska, Lincoln, Nebraska 68583 (H.-H.W., M.R., P.S.);Center for Biotechnology (J.-J.M.R.), and Department of Biochemistry (R.G., J.A.), University of Nebraska, Lincoln, Nebraska 68588; andRiken Plant Science Center, Yokohama 230-0045, Japan (Y.J.).
Jiri
J
Adamec
Department of Agronomy and Horticulture, University of Nebraska, Lincoln, Nebraska 68583 (H.-H.W., M.R., P.S.);Center for Biotechnology (J.-J.M.R.), and Department of Biochemistry (R.G., J.A.), University of Nebraska, Lincoln, Nebraska 68588; andRiken Plant Science Center, Yokohama 230-0045, Japan (Y.J.).
Yusuke
http://orcid.org/0000-0002-8810-6509
Y
Jikumaru
Department of Agronomy and Horticulture, University of Nebraska, Lincoln, Nebraska 68583 (H.-H.W., M.R., P.S.);Center for Biotechnology (J.-J.M.R.), and Department of Biochemistry (R.G., J.A.), University of Nebraska, Lincoln, Nebraska 68588; andRiken Plant Science Center, Yokohama 230-0045, Japan (Y.J.) pstaswick1@unl.edu.
Paul
http://orcid.org/0000-0003-2798-0275
P
Staswick
D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D003517:Cyclopentanes / Q000378:metabolism* / Q000494:pharmacology; D004151:Dipeptides / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005978:Glutathione / Q000378:metabolism; D005981:Glutathione Synthase / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D054883:Oxylipins / Q000378:metabolism* / Q000494:pharmacology; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D030821:Plants, Genetically Modified; D036226:Seedlings / Q000235:genetics / Q000254:growth & development / Q000378:metabolism
D029681:Arabidopsis Proteins; C112279:COI1 protein, Arabidopsis; D003517:Cyclopentanes; D004151:Dipeptides; D054883:Oxylipins; C011006:jasmonic acid; C000609131:GSH2 protein, Arabidopsis; D005981:Glutathione Synthase; D005978:Glutathione; C017341:gamma-glutamylcysteine