ThemicroRNA476a/RFL module regulates adventitious root formation through a mitochondria-dependent pathway inPopulus

AbstractAdventitious root (AR) formation at the base of stem cuttings determines the efficiency of clonal propagation for woody plants. Many endogenous and environmental factors influence AR formation. However, our knowledge about the regulation of AR development by mitochondrial metabolism in plants is very limited. Here we identifiedPopulus-specificmiR476aas a novel regulator of wound-induced adventitious rooting via orchestrating mitochondrial homeostasis in poplar.MiR476aexhibited inducible expression during AR formation and directly targets severalRestorer of Fertility like(RFL) genes encoding mitochondrion-localized pentatricopeptide repeat proteins. Genetic modification ofmiR476-RFLexpression revealed themiR476/RFL-mediated dynamic regulation of mitochondrial homeostasis on AR formation in transgenic poplar. Furthermore, mitochondrial perturbation via exogenous chemical inhibitor validated that themiR476a/RFL-directed AR formation depended on mitochondrial regulation though modulating the auxin pathway. Our results established a miRNA-directed mitochondrion-auxin signaling cascade required for AR development, providing novel insights into the understanding of mitochondrial regulation on plant developmental plasticity.