AtRBP1, which encodes an RNA-binding protein containing RNA-recognition motifs, regulates root growth in Arabidopsis thaliana

AtRBP1 is an RNA-binding protein containing RNA-recognition motifs in Arabidopsis thaliana, homologues of which are not observed in metazoa. Transgenic plants expressing artificial microRNAs for repressing AtRBP1 expression displayed a stunted primary root phenotype during germination. Transgenic plants overexpressing AtRBP1 also displayed the same phenotype. Tight regulation of the AtRBP1 transcript may be required for normal root growth. An in vitro binding assay showed that AtRBP1 preferentially binds to sequences containing UUAGG, GUAGG and/or UUAGU. In vivo selection of RNAs bound to AtRBP1 suggests that transcripts of At3g06780, At4g15910, At5g11760 and At5g07350 are target RNAs of AtRBP1.