Combined genome‐wide association study and epistasis analysis reveal multifaceted genetic architectures of plant height in Asian cultivated rice

Plant height (PH) in rice (Oryza sativa) is an important trait for its adaptation and agricultural performance. Discovery of the semi‐dwarf1 (SD1) mutation initiated the Green Revolution, boosting rice yield and fitness, but the underlying genetic regulation of PH in rice remains largely unknown. Here, we performed genome‐wide association study (GWAS) and identified 12 non‐repetitive QTL/genes regulating PH variation in 619 Asian cultivated rice accessions. One of these was an SD1 structural variant, not normally detected in standard GWAS analyses. Given the strong effect of SD1 on PH, we also divided 619 accessions into subgroups harbouring distinct SD1 haplotypes, and found a further 85 QTL/genes for PH, revealing genetic heterogeneity that may be missed by analysing a broad, diverse population. Moreover, we uncovered two epistatic interaction networks of PH‐associated QTL/genes in the japonica (Geng)‐dominant SD1NIP subgroup. In one of them, the hub QTL/gene qphSN1.4/GAMYB interacted with qphSN3.1/OsINO80, qphSN3.4/HD16/EL1, qphSN6.2/LOC_Os06g11130, and qphSN10.2/MADS56. Sequence variations in GAMYB and MADS56 were associated with their expression levels and PH variations, and MADS56 was shown to physically interact with MADS57 to coregulate expression of gibberellin (GA) metabolic genes OsGA2ox3 and Elongated Uppermost Internode1 (EUI1). Our study uncovered the multifaceted genetic architectures of rice PH, and provided novel and abundant genetic resources for breeding semi‐dwarf rice and new candidates for further mechanistic studies on regulation of PH in rice. Summary statement This study performed GWAS in whole populations and subgroups with distinct SD1 haplotypes, revealed multifaceted genetic architectures of plant height and significant contributions of epistatic interaction between identified QTL/genes to plant height variations in the SD1NIP subgroup.