Designing leaf marginal shapes: Regulatory mechanisms of leaf serration or dissection

The mechanism of formation and evolution of phenotypic diversity is one of the key problems in biodiversity science because phenotype diversity is not only a marker of species diversity, but carries the designs adjusted to environments.Plant leaves exhibit a great deal of morphological variation.Such variation is attributed largely to changes of leaf marginal architecture.Leaf marginal shapes can be described as entire, serrate, lobed (varying in depth and patterns) and dissected (also referred to as compound leaf).The molecular mechanism controlling the development of leaf marginal shape has been intensively studied in Arabidopsis thaliana, Cardamine hirsuta, Solanum lycopersicum, and some other plants.Many important regulatory factors such as transcription factors, small RNAs and plant hormones have been found involved in the development of leaf serration or dissection.Among those factors, the transcription factor NAM/CUC, miR164 and auxin in the auxin efflux module play a central role through a feedback loop, and this regulatory module appears to be conserved across the eudicots; the transcription factors TCPs, SPLs and some other miRNAs also take part in the auxin efflux pathway.Transcription factors of the KNOX family play roles in the development of leaf lobes as well although most of the researches about KNOX genes have focused on their regulation of the morphogenesis of compound leaves.In addition, studies in Arabidopsis, Cardamine and other taxa of the Brassicaceae have shown that the gene RCO promotes the development of leaf dissection by repressing growth at the flanks of protrusions generated by CUC-auxin patterning.The present paper reviews the recent progress and integrate the major results of researches about the molecular mechanisms •综述•