Trifurcate feed-forward regulation of age-dependent cell death involving miR164 in Arabidopsis.

Aging induces gradual yet massive cell death in higher organisms, including annual plants. Even so, the underlying regulatory mechanisms are barely known, despite the long-standing interest in this topic. Here, we demonstrate that ORE1, which is a NAC (NAM, ATAF, and CUC) transcription factor, positively regulates aging-induced cell death in Arabidopsis leaves. ORE1 expression is up-regulated concurrently with leaf aging by EIN2 but is negatively regulated by miR164. miR164 expression gradually decreases with aging through negative regulation by EIN2, which leads to the elaborate up-regulation of ORE1 expression. However, EIN2 still contributes to aging-induced cell death in the absence of ORE1. The trifurcate feed-forward pathway involving ORE1, miR164, and EIN2 provides a highly robust regulation to ensure that aging induces cell death in Arabidopsis leaves.