The GRAS family of putative transcriptional regulators is found throughout the plant kingdom, and these proteins have diverse roles in plant development, including root development, axillary shoot development, and maintenance of the shoot apical meristem (Bolle, 2004). GRAS proteins show conserved residues in the C terminus but contain a variable N terminus with homopolymeric stretches of certain amino acids. It has recently been shown that two GRAS proteins that regulate root growth, SCARECROW (SCR) and SHORTROOT (SHR), interact with each other (Cui et al., 2007), while a class of GRAS proteins involved in regulating plant growth, the DELLA proteins, interact with a transcription factor involved in phytochrome signaling (de Lucas et al., 2008; Feng et al., 2008).
