Blue light and NAA treatment significantly improve rooting on single leaf-bud cutting of Chrysanthemum via upregulated rooting-related genes

Single leaf-bud cutting has been attempted in an effort to produce multiple individuals; however, these cuttings produce individuals of irregular quality with different rooting abilities based on the cutting positions of the mother stem. We evaluated whether light and 1-naphthaleneacetic acid (NAA) treatment can improve root formation from relatively poor stem cuttings on single leaf-bud cuttings and which factor is more effective for rapid root formation. Blue (BL), red (RL), and fluorescent (FL) with/without NAA were independently applied to single leaf-bud cuttings. High-intensity BL together with NAA treatment efficiently induced adventitious root formation and improved root formation from poor stems. We also evaluated relative expression levels of seven kinds of rooting-related genes on cutting processes to define the critical light factor leading to rapid adventitious rooting. CmLBD1 was significantly upregulated after 5 day BL treatment and initiated rooting, whereas the expressions of other rooting-related genes were significantly increased by fluorescent light after 14 days cutting initiation.