The Molecular Basis of Age-Modulated Plant De Novo Root Regeneration Decline in Arabidopsis thaliana

Plants possess a regeneration capacity that enables them to survive after wounding. For example, detached Arabidopsis thaliana leaves are able to form adventitious roots from their cutting sites even in the absence of exogenous hormone supplements, as process termed de novo root regeneration (DNRR). Wounding rapidly induces auxin biosynthesis at the cutting sites and then elicits a signaling cascade to promote cell fate transitions and finally generate the adventitious roots. However, rooting rates in older plants are much lower than in younger leaf explants. In this review, we highlight the recent breakthroughs in the understanding of DNRR decay in older plants from at least two independent signaling routes: (i) via the accumulation of EIN3 protein in older plants, which directly suppresses expression of WUSCHEL RELATED HOMEOBOX (WOX) genes to inhibit rooting; (ii) the miR156-SPLs-AP2/ERFs pathway, which modulates root regeneration by reducing auxin biosynthesis.