Figure 8.

A working schema of the senescence pathway performed by the dually located WHY1 in combination with H₂O₂. The nuclear isoform of WHY1 is represented as both a large molecular mass protein (L-band, bigger letters) and a small molecular mass protein (S-band, smaller letters). The WHY1 has dual functions in plastids and the nucleus. Loss of WHY1 or shifting the proteins to plastids increases H₂O₂ accumulation through an unknown pathway, resulting in a senescence phenotype. Elevated H₂O₂ represses nuclear WHY1 accumulation, promoting H3K9ac enrichment and RNAP II recruitment globally and specifically at the WRKY53 locus, and stimulating early senescence. Thus, distribution of WHY1 organelle isoforms and the putative feedback of H₂O₂ form a circularly integrated regulatory network during plant senescence in Arabidopsis. Plastid is shown as a green ovary, nucleus as a grey ovary, lines for regulation, fat arrows for transfer or translocation, and broken lines for uncertainty.