SLL1-ZH Regulates Spikelets Architecture and Grain Yield in Rice

The spikelet developmental processes that control structure and floral organ identity play critical roles in rice grain yield formation. In this study, we characterized a novel rice mutant, SLL1-ZH, which exhibits a variety of defective agronomic characters, including semi-dwarf, rolling leaf, deformed panicles, and reduced grains production. Morphological analysis also revealed that the SLL1-ZH mutant shows numerous defects of floral organs, such as cracked glumes, hooked and thin lemmas, shrunken but thickened paleas, an indeterminate number of stamens and stigmas, and heterotopic ovaries. Map-based cloning identified a single nucleotide substitution (C to G) in the first exon of LOC_Os09g23200 that is responsible for the SLL1-ZH phenotype. In addition, qPCR analysis showed a significant change in the relative expression of SLL1-ZH in the mutant during inflorescence differentiation and in the different floral organs. Transcription of rice floral organ development-related factors also changed significantly in the mutant. Therefore, our results suggested that SLL1-ZH plays a great role in plant growth, spikelet development, and grain yield in rice.