Evaluating the potential of SHI expression as a compacting tool for ornamental plants

Control of plant growth, especially elongation of stems, is important in modern plant production, and many plant species, including cereals, grasses, fruit trees and ornamentals, are regularly treated chemically to control their stature and flowering time. Chemical treatments ensure short, homogenous plants, which are more robust and easy to harvest, transport and sell. Although growth retardants are an expensive and undesirable step in plant production, it is unfortunately necessary at present. Compact growth is desirable in most ornamentals and this trait can be difficult to obtain by traditional breeding. As an alternative, biotechnology could provide plant varieties with optimized growth habits. This review is an introduction to the family of SHI transcription factors, which has recently been used to produce compact plants of very diverse species. The possible functions and regulations of the SHI proteins are discussed, and the potential of using overexpression as means to dwarf plants is assessed. In conclusion the breeding of some species, especially flowering ornamentals, could benefit from this strategy. Furthermore, detailed knowledge about the role of SHI proteins in plant growth and development could help shed more light on the interactions between plant hormone signaling pathways.