MicroRNA-mediated regulation of flower development in grasses

Abstract

Flower structure in grasses is very unique. There are no petals or sepals like in eudicots but instead flowers develop bract-like structures –palea and lemma. Reproductive organs are enclosed by round lodicule that not only protects reproductive organs but also play important role during flower opening. First genetic model for floral organ development was proposed 25 years ago and it was based on the research on model eudicots. Since then studies have been made to answer the question whether this model could be applicable in case of monocots. Genes from all found in eudicots classes have been also indentified in genomes of such monocots like rice, maize or barley. What’s more it seems that miRNA-mediated regulation of floral organ genes that was observed in case of Arabidopsis thaliana also has a place in monocots. MiRNA172, miRNA159, miRNA171 and miRNA396 regulate expression of floral organ identity genes in barley, rice and maize affecting various features of flower structure from formation of lemma and palea to development of reproductive organs. Model of floral development in grasses and its genetic regulation in not yet fully characterized. Further studies on both model eudicots and grasses are needed to unravel this topic. This review provides general overview of genetic model of flower organ identity specification in monocots and it’s miRNA-mediated regulation.