Abstract
BACKGROUND: The high-frequency induction rate of haploid is crucial for double haploid (DH) breeding. The combination of multiple haploid-induced genes, such as ZmPLA1/MATL/NLD and ZmDMP, can synergistically enhance the haploid induction rate (HIR) in maize. However, the potential synergistic effects between OsMATL and OsDMP genes in rice remain unclear. RESULTS: Knocking out OsMATL in both HuaHang No.48 (HH48) and Nipponbare (NIP) cultivars resulted in reduced seed setting rate (SSR) and haploid induction (HI). Notably, in this study, the HI capacity of OsMATL knockout mutants in indica rice surpassed that of japonica rice knockout mutants, with the proton active site in the third exon exhibiting a higher HIR compared to the first and fourth exons. Furthermore, when OsDMP1 or OsDMP3 was combined with OsMATL, they increased HIR, and an antagonistic relationship was observed between HIR and SSR in HH48 (matl4dmp1) and HH48 (matl4dmp3). CONCLUSIONS: In rice, the proton active site in the third exon of OsMATL exhibited higher induction efficiency, and OsDMP1 or OsDMP3 exerted a synergistic effect with OsMATL. These findings provide a foundation for further research on DH breeding in rice.