Loss of function of OsL1 gene cause early flowering in rice under short-day conditions

Heading date is one of the important agronomic traits that affects rice yield. In this study, we cloned a new rice B3 family gene, OsL1, which regulates rice heading date. Importantly, osl1-1 and osl1-2, two different types of mutants of OsL1 were created using the gene editing technology CRISPR/Cas9 system and exhibited 4 days earlier heading date than that of the wild type under short-day conditions. Subsequently, the plants overexpressing OsL1, OE-OsL1, showed a 2-day later heading date than the wild type in Changsha and a 5-day later heading date in Lingshui, but there was no significant difference in other yield traits. Moreover, the results of subcellular localization study indicated that OsL1 protein was located in the nucleus and the expression pattern analysis showed that OsL1 gene was expressed in rice roots, stems, leaves, and panicles, and the expression level was higher at the root and weak green panicle. In addition, the OsL1 gene was mainly expressed at night time under short-light conditions. The transcriptomic analysis indicated that OsL1 might be involved in the Hd1-Hd3a pathway function. Together, our results revealed that the cloning and functional analysis of OsL1 can provide new strategy for molecular design breeding of rice with suitable fertility period.