Vein patterning and evolution in C4plants

Abstract

The C4photosynthetic pathway provides a platform to gain insight into the formation, regulation, and biological consequences of leaf vein pattern modification. This review examines the functional role of the vascular system in C4photosynthesis and the development of veins in C3and C4plants, highlighting the contribution of vasculature in the evolution of the C4pathway. With interest in developing C3plant crops into C4systems, it is essential to understand vascular patterning as a necessary element for C4functioning. Leaf venation in C4plants generally shows a higher vein density through a greater network complexity (more veins) compared with the ancestral C3condition. Thus, C4plants can provide a model that links the development of vein patterning with evolutionary selection pressures and molecular mechanisms (i.e., modifications of different components of vascular development). Numerous studies, including a comparative C3and C4Flaveria case study, highlight that the overall process of vein formation and patterning is complex, involving interactions between procambium and ground meristem during leaf ontogeny, and points to potential roles of changes in auxin production, transport, and perception.