ETHYLENE INSENSITIVE 3 suppresses plant root regeneration from leaf explants and mediates age-regulated regeneration decline.

Powerful regeneration ability enables plant survival when plants are wounded. For example, adventitious roots can regenerate from the cutting site in detached leaf explants, even in the absence of any exogenous plant hormone treatment. This process is known as root regeneration (DNRR). Although the developmental program underlying DNRR is known, the precise regulatory mechanisms underlying DNRR are not completely understood. Here, we show that ethylene treatment or genetic activation of transcription factor ETHYLENE INSENSITIVE 3 (EIN3) strongly suppresses DNRR rates, while a mutant lacking EIN3 and its homolog EIL1 () displays a higher DNRR capacity. Previous reports have shown that the sequential induction of ()/ and / expression is required for the establishment of DNRR. We found that EIN3 directly targets and promoter regions to suppress their transcription. Furthermore, older plants show enhanced EIN3 activity, and repressed expression of and Taken together, these results illustrate that plant aging at least partially takes advantage of EIN3 as a negative regulator to suppress DNRR through inhibiting the activation of WOX genes.