DICERLIKE1 Functions in Maize Development

MiRNAs are small non-coding RNAs that reduce expression of target mRNAs and are key regulators of plant development and physiology.  We have isolated a maize mutant, fuzzy tassel (fzt), that contains a mutation in DICER-LIKE1, a key enzyme required for miRNA biogenesis in plants.  Small RNA sequencing analysis showed that most miRNAs are moderately reduced in fzt plants and a few miRNAs are dramatically reduced.  fzt plants have striking reproductive defects, including indeterminate meristems, fasciation, and alterations in sex determination.  fzt plants also have dramatically reduced plant height and shorter, narrower leaves with leaf polarity and phase change defects. Reduced levels of known miRNAs can explain some aspects of the fzt phenotype, including miRNAs that control meristem determinacy, phase change, and leaf polarity.  MiRNAs responsible for other aspects of the fzt phenotype are unknown and likely to be those miRNAs most severely reduced in fzt mutants.