Abstract
For the comprehensive understanding of the evolution of plant flowers, it is important to study the development of monocot flowers as well as eudicot flowers. In grasses, inflorescence comprise of unique structural units, spikelet and floret. The rice spikelet has one floret, which is subtended by two tiny glume-like organs, called sterile lemma. The sterile lemma is thought to be a rudimentary organ of two lateral florets, which have been degenerated during rice evolution. We have focused on a rice mutant, sterile lemma of which are longer than those of wild type, to elucidate the developmental mechanism of the sterile lemma and their evolutionary origin. Here, we will report the results of molecular genetic analyses and discuss evolution of rice spikelet.