Functional Analysis of CLE26 in Controlling De Novo Root Regeneration from Detached Arabidopsis Leaves

<i>De novo</i> root regeneration is the process by which adventitious roots form around the wound site from wounded or detached plant organs. The <i>de novo</i> root regeneration process has been widely exploited in cutting technology used for vegetative propagation. Here, we employed detached leaf explants from <i>Arabidopsis thaliana</i> to form adventitious roots for studying the process of <i>de novo</i> root regeneration. GUS staining showed that the expression of <i>CLAVATA3/EMBRYO SURROUNDING REGION-RELATED26</i>(<i>CLE26</i>) was gradually increased surrounding the wound site of leaf explants during adventitious root formation. Semi-thin sections further showed that the expression pattern of <i>CLE26</i> was closely linked to the formation of adventitious roots. Next, genetic analyses confirmed that the <i>CLE26</i> gene was involved in <i>de novo</i> root regeneration. Furthermore, RNA sequencing (RNA-seq) of the leaf explants revealed that stress-related genes might be involved in <i>CLE26</i>-mediated adventitious root formation. Specifically, genes associated with the hydrogen peroxide catabolic process and oxidative stress response were predominantly upregulated in the <i>cle26</i> mutant. In contrast, genes involved in the response to salicylic acid were largely downregulated in the <i>cle26</i> mutant. Overall, our study indicates that the mutation in <i>CLE26</i> might upregulate the expression of genes involved in reactive oxygen species metabolism or suppress the expression of genes associated with salicylic acid synthesis, thus promoting the formation of adventitious roots. These findings suggest that <i>CLE26</i> is a potential candidate for the genetic improvement of adventitious rooting in cuttings.