Figure 10.

Tentative Model of ONAC054-Mediated Leaf Senescence through ABA Signaling.

Considering the low expression of ONAC054α and ONAC054β and the fact that the TMD is not cleaved in the absence of ABA, the accumulation of active ONAC054 proteins in the nucleus (ONAC054β and ONAC054α△TM) is low (top) under normal growth conditions. In the early phase of ABA treatment, ONAC054β dramatically accumulates in the nucleus (middle). In the late phase of ABA treatment, ONAC054α accumulates in addition to ONAC054β (bottom). Furthermore, the TMD of ONAC054α is cleaved, leading to the high accumulation of active ONAC054 proteins in the nucleus, which promotes leaf senescence through direct activation of OsABI5 and NYC1 transcription.