The LBD11-ROS feedback regulatory loop modulates vascular cambium proliferation and secondary growth in Arabidopsis

Vascular cambium produces the phloem and xylem, vascular tissues that transport resources and provide mechanical support, making it an ideal target for crop improvement. However, much remains unknown about how vascular cambium proliferates. In this study, through pharmaceutical and genetic manipulation of reactive oxygen species (ROS) maxima, we demonstrate a direct link between levels of ROS and activity of LATERAL ORGAN BOUNDARIES DOMAIN 11 (LBD11) in maintaining vascular cambium activity. LBD11 activates the transcription of several key ROS metabolic genes, including PEROXIDASE 71 and RESPIRATORY BURST OXIDASE HOMOLOGS D and F, to generate local ROS maxima in cambium, which in turn enhance the proliferation of cambial cells. In a negative feedback mechanism, higher ROS levels then repress LBD11 expression and maintain the balance of cambial cell proliferation. Our findings thus reveal the role of a novel LBD11/ROS-dependent feedback regulatory system in maintaining vascular cambium-specific redox homeostasis and radial growth in plants.