Altered ABA, proline and hydrogen peroxide in an Arabidopsis glutamate:glyoxylate aminotransferase mutant.
Plant responses to abiotic stress are determined both by the severity of the stress as well as the metabolic status of the plant. Abscisic acid (ABA) is a key component in integrating these various signals and controlling downstream stress responses. By screening for plants with decreased RD29A:LUC expression, we isolated two alleles, glutamate:glyoxylate transferase1-1 (ggt1-1) and ggt1-2, of a mutant with altered ABA sensitivity. In addition to reduced ABA induction of RD29A, ggt1-1 was altered in ABA and stress regulation of Delta1-pyrroline-5-carboxylate synthase, proline dehydrogenase and 9-cis-epoxycarotenoid dioxygenase 3, which encode enzymes involved in Pro and ABA metabolism, respectively. ggt1-1 also had altered ABA and Pro contents after stress or ABA treatments while root growth and leaf water loss were relatively unaffected. A light-dependent increase in H2O2 accumulation was observed in ggt1-1 consistent with the previously characterized role of GGT1 in photorespiration. Treatment with exogenous H2O2, as well as analysis of a mutant in nucleoside diphosphate kinase 2 which also had increased H2O2 content but is not involved in photorespiration or amino acid metabolism, demonstrated that the greater ABA stimulation of Pro accumulation in these mutants was caused by altered H2O2 content as opposed to other metabolic changes. The results suggest that metabolic changes that alter H2O2 levels can affect both ABA accumulation and ABA sensitivity.
Verslues
Paul E
PE
Department of Botany and Plant Sciences, Institute for Integrative Genome Biology, University of California, Riverside, CA 92521, USA.
Kim
Yong-Sig
YS
Zhu
Jian-Kang
JK
D000040:Abscisic Acid / Q000378:metabolism* / Q000494:pharmacology; D000483:Alleles; D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism*; D009154:Mutation; D011392:Proline / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D000637:Transaminases / Q000235:genetics* / Q000378:metabolism
D029681:Arabidopsis Proteins; C520629:RD29a protein, Arabidopsis; D017382:Reactive Oxygen Species; D000040:Abscisic Acid; D011392:Proline; D006861:Hydrogen Peroxide; C520630:At1g23310 protein, Arabidopsis; D000637:Transaminases; C020649:glutamate-glyoxylate aminotransferase