A Series of Novel Alleles of Modulating Heading and Salt Tolerance in Rice

Rice ( L.) is a staple crop for nearly half of the global population and one of China's most extensively cultivated cereals. Heading date, a critical agronomic trait, determines the regional and seasonal adaptability of rice varieties. In this study, a series of mutants ( to ) exhibiting extremely late heading under both long-day (LD) and short-day (SD) conditions were identified from an ethyl methanesulfonate (EMS) mutant library. Using MutMap and map-based cloning, the causative gene was identified as a novel allele of ///. Functional validation through CRISPR/Cas9 knockout and complementation assays confirmed its role in regulating heading. The mutation was found to cause intron retention due to alternative splicing. encodes a Cys-2/His-2-type zinc finger transcription factor with an IDD domain and transcriptional activity in yeast. Its expression peaks in developing leaves before heading and spikes during reproductive conversion. In mutants, delayed heading resulted from downregulating the - pathway genes. Salinity stress significantly hampers rice growth and productivity. Transcriptomic analysis of and ZH8015 seedlings exposed to salt stress for 24 h identified 5150 differentially expressed genes (DEGs) at the seedling stage, predominantly linked to stress response pathways. was revealed as a modulator of salt tolerance, likely through the regulation of ion transport, enzyme activity, and antioxidant systems. This study establishes as a pivotal factor in promoting heading while negatively regulating salt tolerance in rice.