UC San Diego

The high quality annotation of the Arabidopsis thaliana genome allows biologists to predict the target transcripts of known microRNAs (miRNAs). The transcript of At1g27340, e.g. UNUSUAL LATERAL ORGANS (ULO), is the predicted target of the miRNA394 family. The ULO protein is predicted to contain an F-BOX domain and a Kelch protein-protein interaction domain by amino acid sequence similarity. Given these predicted domains, it is possible ULO may be recognizing proteins and mediating their decay. miRNA resistant versions of ULO result in polarity defects in all lateral organs derived from the shoot apical meristem. These defects are similar to what is seen in loss-of- function alleles of the CLASS III HD-ZIP genes, indicating ULO may negatively regulate this gene family. Genetic interactions between HD-ZIP III mutants and miRNA resistant alleles of ULO support this finding. Using molecular biology tools discussed here, we have attempted to characterize the expression and function of ULO and its corresponding microRNA family 394