Abstract:Organ size is an important morphological trail in plants, and shows significant differences among species. Organ growth is influenced by environmental factors, such as light and nutrients; however, it is determined by the intrinsic information of cell number and cell size. A large number of genes involved in regulation of cell proliferation and/or cell expansion have been identified, and their up-regulated or down-regulated expression change organ size and accelerate organ growth by means of transcription regulation, protein synthesis and modification, hormonal regulation and cell-wall loosening, and so on. In spite of this, these genes act through relative independent pathways, making it difficult to demonstrate an integrated regulation network in plants. Further challenges will be the regulation pattern and molecular changes in different plant species. Several genes participated in organ growth have been used in crop breeding, and produced significantly large crops. Similarly, characterization of the genes involved in organ size control of Chinese herbs to artificially promote organ size and morphology at the molecular level will contribute to overcome the shortage and endangerment of medicinal plants.