Chapter 16 - The Role of TCP Transcription Factors in Shaping Flower Structure, Leaf Morphology, and Plant Architecture

Abstract

TCP (TEOSINTE BRANCHED1/CYCLOIDEA/PROLIFERATING CELL FACTOR) transcription factors are a family of plant-specific proteins that contain a TCP domain, a noncanonical basic helix–loop–helix structure involved in DNA binding, and protein–protein interactions. Some TCP proteins have important functions in plant development, such as control of leaf shape and flower symmetry, and the suppression of lateral shoot branching. The TCP family is divided into two classes, class I and class II. Class II is further subdivided into subclasses CINCINNATA (CIN) and CYCLOIDEA/TEOSINTE BRANCHED1 (CYC/TB1). Whereas early studies proposed antagonistic roles for class I and II proteins on the control of cell proliferation, here we describe recent work which supports the belief that both protein types are functionally interconnected and in some cases contribute to some functions during plant development. We outline the role of class I and CIN genes in the modulation of meristem gene expression, to control simple and compound leaf maturation. In addition, we review the roles of class I and class II CIN and CYC/TB1 genes in flower development, and comment on recent advances in our understanding of the up- and downstream pathways of CYC/TB1 genes in the control of lateral shoot branching. Finally, we discuss how these TCP transcription factors are integrated in the hormone-signaling pathways that control these developmental processes.