Isolation of OsMetAP10, a Peptidase_M24 Superfamily Gene, Regulating Heading Date in Rice

The heading date is one of the important traits in rice, which greatly affects grain yield and regional adaptability. Although the flowering pathways in rice have been extensively investigated, the genes involved in flowering remain largely unknown. Here, we report a rice <i>lhd</i> mutant, which showed late flowering under both long-day (LD) and short-day (SD) conditions. Through MutMap+ and linkage analysis, a deletion mutation in <i>OsMetAP10</i> was inferred as the most likely candidate for <i>lhd</i> late flowering. <i>OsMetAP10</i> encodes a methionine aminopeptidase that belongs to the peptidase_M24 subfamily III. The <i>OsMetAP10</i> gene is constitutively expressed in rice and is induced by light, with a rhythmic expression pattern. <i>OsMetAP10</i> knockout lines displayed late heading as the <i>lhd</i> mutation, while no alternations in morphology and heading were observed on <i>OsMetAP10</i> overexpression lines, further confirming the mutation of <i>OsMetAP10</i> as responsible for the late heading of <i>lhd</i>. Through RT-qPCR and transcriptome analysis, we revealed that the upregulated expression of the <i>FT-like</i> gene <i>OsFLT4</i>, a negatively flowering regulator, and the downregulation of flower development-related genes, <i>OsMADS14</i>, <i>OsMADS15</i>, and <i>OsMADS34</i>, played critical roles in determining the late flowering of the <i>OsMetAP10</i> mutation. This study reports a new gene affecting flowering and provides a new insight into the role of <i>OsMetAP10</i> in regulating rice heading.