We are interested in the molecular mechanisms that regulate plant growth and development. In particular, we are focusing on the members of GRAS family in Arabidopsis. GRAS proteins belong to a plant-specific transcription factor family, named after the three founding members, GAI, RGA, and SCR. Currently, 33 GRAS members including an expressed pseudogene have been identified in the Arabidopsis genome. With a reverse genetic approach, we constructed a “phenome-ready unimutant collection” of the Arabidopsis GRAS genes. With the use of various tools and techniques, we are trying to elucidate the biological roles of the members of GRAS family. Interestingly, SCL6, SCL22, and SCL27 are the targets of miR171, and the transcripts of SCL6, SCL22, and SCL27 are cleaved by the action of miR171. Thus, we have begun to investigate the roles of these members in relation to miR171 in growth and development by a combination of molecular genetic and genomic approaches. In addition, we recently found that SCL16 appeared to be an expressed pseudogene with a single intron (88 bp), because the deduced amino acid sequence of SCL16 with all the signature motifs contains frame shift and nonsense mutations in the ORF, suggesting that it has no potential to encode a functional GRAS protein. We are also investigating the role of this expressed pseudogene. Hopefully, our large-scale phenome analysis provides an opportunity for the comprehensive evaluation on the roles of the Arabidopsis GRAS genes. In addition, our phenome-ready unimutant collection of the GRAS family will be a useful resource to better understand individual GRAS proteins that play diverse roles in plant growth and development.