The palea and lemma of rice spikelets have similar histology, which are composed of silicified cells, fibrous sclerenchyma, spongy parenchymatous cells, and nonsilicified cells.The lemma partially encloses the palea and has five vascular bundles whereas the palea has three.Our previous studies demonstrated that Shallot-Like1 (SLL1) modulated leaf rolling by regulating the development of leaf abaxial cells (Zhang and Xu et al., 2009).In addition to leaf rolling, our further studies indicated the roles of SLL1 in the dev,elopment of rice palea and lemma.Observations showed that the palea and lemma of sll1-1 and sll1-2 mutants differed from wild type in shape and failure to close.Scanning electron microscopy analysis showed that in the epidermis of palea and Iemma in sll1-1 and sll1-2, some epidermal cells were not silicified and contained more microhairs.Moreover, cross sectional analysis revealed that in sll1-1 and sll1-2, the layer of sclerenchymatous cells of both palea and lemma was not fully developed, and five vascular bundles were observed in the palea, suggesting a partial developmental transformation of palea into lemma.These results imply that SLL1 may play a critical role in the development of palea and lemma by regulating the formation of silicified cells, sclerenchymatous cells and vascular bundles.