SDR3.1 negatively regulates seed dormancy in Poaceae crops.

Abstract

Elucidating the molecular mechanisms that govern seed dormancy is important for developing crops with improved resistance to preharvest sprouting (PHS). A series of seed dormancy genes have been cloned, but the connections among different seed dormancy genes remain poorly understood. Here, we have revealed the relationship between two important dormancy quantitative trait loci (QTLs): SDR3.1 and Sdr4. SDR3.1 formed complexes with ABI3 and ABI5 and suppressed their activation of Sdr4 transcription. Haplotype analysis showed that the germination rate of SDR3.1 L-type and Sdr4 n- or K-type combinations was low, and the parents of modern core breeding do not contain l-type. Analysis of transgenic plants confirmed that orthologs of SDR3.1 have conserved functions in controlling seed dormancy in rice (Oryza sativa L.), foxtail millet (Setaria italica (L.) P. Beauv.), and maize (Zea mays), but they have different molecular regulatory mechanisms. This study uncovers the OsSDR3.1-ABI3/ABI5-Sdr4 regulatory module conferring improved PHS resistance, while establishing an effective approach to characterize core functional genes for important agronomic traits across Poaceae species with rice as a model.