Chapter 23 - Intercellular Movement of Plant Transcription Factors, Coregulators, and Their mRNAs

Abstract

Due to their sessile lifestyle, plants have evolved numerous noncell-autonomous signaling pathways, many of which involve transcription factors (TFs) or coregulators. These long- or short-range signals respond to environmental cues, are transported through plasmodesmata, may be graft transmissible, and are mobile in the form of a protein or a full-length mRNA. Whereas there are hundreds of proteins and full-length mRNAs that move through the phloem system, the functions of most are unknown. This chapter focuses on the most prominent examples of TFs that (1) move from cell to cell or (2) are mobile through the sieve element system and affect key developmental processes. Significant RNAs that move include a BEL1-like TF mediating tuberization in potato, GA INSENSITIVE, KNOTTED1-types, and two Flowering Locus T types. Whereas there are numerous examples of TFs that move cell to cell in protein form, there is sparse evidence of these trafficking through the sieve element system. Established as critical for flowering in several plant species, protein movement from leaf to the shoot apex occurs for the ubiquitous transcriptional coregulator, Flowering Locus T.