Abstract:

Glutathione reductase (GR) catalyzes the reduction of glutathione disulfide (GSSG) to reduced glutathione (GSH) and participates in the ascorbate-glutathione cycle, which scavenges H₂O₂. Here, we report that chloroplastic/mitochondrial GR2 is an important regulator of leaf senescence. Seed development of the homozygous gr2 knockout mutant was blocked at the globular stage. Therefore, to investigate the function of GR2 in leaf senescence, we generated transgenic Arabidopsis plants with decreased GR2 using RNAi. The GR2 RNAi plants displayed early onset of age-dependent and dark- and H₂O₂-induced leaf senescence, which was accompanied by the induction of the senescence-related marker genes SAG12 and SAG13. Furthermore, transcriptome analysis revealed that genes related to leaf senescence, oxidative stress, and phytohormone pathways were upregulated directly before senescence in RNAi plants. In addition, H₂O₂ accumulated to higher levels in RNAi plants than in wild-type plants and the levels of H₂O₂ peaked in RNAi plants directly before the early onset of leaf senescence. RNAi plants showed a greater decrease in GSH/GSSG levels than wild-type plants during leaf development. Our results suggest that GR2 plays an important role in leaf senescence by modulating H₂O₂ and glutathione signaling in Arabidopsis.

Ding S, Wang L, Yang Z, Lu Q, Wen X, Lu C (2016) Decreased glutathione reductase2 leads to early leaf senescence in Arabidopsis. J Integr Plant Biol 58: 29–47 doi: 10.1111/jipb.12371

Key words: Arabidopsis thaliana, ascorbate-glutathione cycle, glutathione reductase2, hydrogen peroxide, leaf senescence