() regulates lemma development and affects rice grain yield.

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In grass, the lemma is a unique floral organ structure that directly determines grain size and yield. Despite a great deal of research on grain enlargement caused by changes in glume cells, the importance of normal development of the glume for normal grain development has been poorly studied. In this study, we investigated a rice spikelet mutant, (), which developed florets with a slightly degenerated or rod-like lemma. More importantly, also showed a significant reduction in grain length and width, seed setting rate, and 1000-grain weight, which led to a reduction in yield. The results indicate that the mutation of the gene further affects rice grain yield. Map-based cloning shows a single-nucleotide substitution from T to A within , causing an amino acid mutation of Leu-34 to His-34 in the mutant. Compared with the wild type, the expression of in was significantly reduced, which might be caused by single base substitution. In addition, the expression level of in was lower than that of the wild type. RT-qPCR results show that the expression of some floral organ identity genes was changed, which indicates that the gene regulates lemma development by modulating the expression of these genes. The present results suggest that the normal expression of is necessary for the formation of lemma and the normal development of grain morphology and therefore has an important effect on the yield.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s12298-023-01297-6.