Heterosis-associated genes confer high yield in super hybrid rice

摘要

Key message Heterosis QTLs, includingqSS7andqHD8,with dominance effects were identified through GBS and large-scale phenotyping of CSSLs and hybrid F(1)populations in a paddy field. Heterosis has contributed immensely to agricultural production, but its genetic basis is unclear. We evaluated dominance effects by creating two hybrid populations: a B-homo set with a homozygous background and heterozygous chromosomal segments and a B-heter set with a heterozygous background and homozygous segments. This was achieved by crossing a set of 156 backcrossed-derived chromosome segment substitution lines (CSSLs) with their recurrent parent (9311), the male parent of the first super-high-yield hybrid Liangyoupei9 (LYP9), and with the female parent (PA64s) of the hybrid. The CSSLs were subjected to a genotyping-by-sequencing analysis to develop a genetic map of segments introduced from the PA64s. We evaluated the heterotic effects on eight yield-related traits in the hybrid variety and F(1)populations in large-scale field experiments over 2 years. Using a linkage map consisting of high-density SNPs, we identified heterosis-associated genes in LYP9. Five candidate genes contributed to the high yield of LYP9, withqSS7andqHD8repeatedly detected in both B-hybrid populations. The heterozygous segments harboringqSS7andqHD8showed dominance effects that contributed to the heterosis of yield components in the hybrid rice variety Liangyoupei9.