Genetic regulation of stem elongation and thickening in ornamental plants: a review

Abstract The stem, a crucial organ that connects the root and aboveground parts, is responsible for transporting water and nutrients. This review synthesizes the current understanding of stem development in ornamental plants. We first outline the morphological and physiological characteristics of stem elongation and stem thickening. Subsequently, we examine the roles of key genes, plant hormones, and cell wall components in regulating stem growth, mechanical strength, and overall plant architecture. We also analyze how environmental factors (e.g. temperature, light, water, and nutrients) and hormonal and genetic networks modulate stem development. Particular emphasis is placed on the functions of auxin, gibberellins, and brassinosteroids. Recent studies in ornamental plants such as Prunus, Chrysanthemum, and Paeonia have illuminated the advances in cultivation techniques and gene identification associated with cellular processes, cell wall synthesis, hormone biosynthesis, and signal transduction. Looking forward, we highlight emerging research directions, including the use of advanced imaging and artificial intelligence for phenotypic analysis, and the integration of multi-omics data within a ‘Breeding 5.0’ framework. Ultimately, this review aims to support the targeted breeding of ornamental plants with optimized stem traits, enhancing both aesthetic value and production efficiency.