A complex regulatory network underlies de novo root regeneration in red maple (Acer rubrum)

Abstract

Red maple (Acer rubrum L.) is ornamentally and medicinally valuable; however, its wider application is restricted by the difficulty of rooting from cuttings. We analyzed paraffin sections of roots regenerating using RNA-Seq to decipher the mechanisms underlying de novo root regeneration (DNRR) in red maple cuttings. This work contributes to improving the rooting rate and shortening the rooting time. We identified four stages during DNRR: 0 days after induction (DAI), no new cell formation; 30 DAI, root meristem organization; 36 DAI, root primordium formation; and 45 DAI, root elongation growth. We identified 37 959 unigenes by de novo assembly, with 25 477 (67.12%) functionally annotated. Furthermore, we identified 1285 differentially expressed genes (DEGs) between adjacent stages. From Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment networks, we found evidence that plant hormones are significant in DNRR of red maple cuttings. Specifically, 149 DEGs functioned in hormone signal transduction pathways, particularly those involving ethylene, auxin, and jasmonic acid (JA). We propose a complex regulatory network model of DNRR in red maple, where wounding induces root regeneration through pathways of JA and auxin signaling. The transcription factors ETHYLENE RESPONSE FACTOR 109 (ERF109) and ERF115 integrate JA signal and participate in DNRR directly by regulating SCARECROW activation and indirectly by promoting auxin biosynthesis.