Plant trihelix transcription factors and their functions in development and stress

Transcription factors (TFs) are central hubs connecting plant physiology and development. The family of trihelix transcription factors (TTFs), also known as GT factors, feature a helix-loop-helix-loop-helix DNA-binding domain and protein-protein interaction domains, including a characterized extended coiled-coil domain. Members of the family participate in developmental processes such as embryogenesis, flower development, seed shattering, and regulation by ethylene and abscisic acid (ABA). The association of specific TTFs with DNA and chromatin-remodeling complexes results in histone modifications that reprogram gene expression, both during the hormonal responses and in the control of transposon silencing. In addition, TTFs play key roles in the responses to abiotic stresses such as those suffered under water deficit, submergence, salinity, and cold. Moreover, members of the family are also important for plant immunity to bacterial and fungal pathogens. This review provides an update on the functions and regulatory mechanisms of TTFs. Recent research emphasizes the relevance of molecular interactions for their functions, which include roles in gene regulatory networks for specific cell populations. Finally, a perspective on research avenues derived from the knowledge of this TF family is provided, in the context of global warming and climate change.