The GRAS gene family in Arabidopsis: sequence characterization and basic expression analysis of the SCARECROW-LIKE genes

Mutations at the SCARECROW(SCR) locus in Arabidopsis thaliana result in def ective radial patterning in the root and shoot. The SCR gene product contai ns sequences which suggest that it is a transcription factor. A number of A rabidopsis Expressed Sequence Tags (ESTs) have been identified that encode gene products bearing remarkable similarity to SCR throughout their carboxy l-termini, indicating that SCR is the prototype of a novel gene family. The se ESTs have been designated SCARECROW-LIKE (SCL). The gene products of the GIBBERELLIN-INSENSITIVE (GAI) and the REPRESSOR of ga1-3 (RGA) loci show h igh structural and sequence similarity to SCR and the SCLs. Sequence analys is of the products of the GRAS (GAI, RGA, SCR) gene family indicates that t hey share a variable amino-terminus and a highly conserved carboxyl-terminu s that contains five recognizable motifs. The SCLs have distinct patterns o f expression, but all of those analyzed show expression in the root. One of them, SCL3, has a tissue-specific pattern of expression in the root simila r to SCR. The importance of the GRAS gene family in plant biology has been established by the functional analyses of SCR, GAI and RGA.