2026 年 76 巻 2 号 p. 180-189
Optimizing heading date to suit local conditions is key to maximizing yield potential. ‘Haruka Nijo’, a two-rowed barley (Hordeum vulgare L.) cultivar developed for the Kyushu region of Japan, is early-heading and has superior yield performance compared to the standard cultivar ‘Nishinohoshi’. To identify genomic regions associated with early-heading in ‘Haruka Nijo’, we conducted analysis of quantitative trait loci (QTLs) using recombinant progeny of ‘Haruka Nijo’ × ‘Nishinohoshi’ (heading date difference: 2.4–6.0 days). A stable QTL, designated QHD.HN-5H, was detected near the centromere of chromosome 5H. This QTL explained 30.3–46.1% of the phenotypic variance and consistently conferred 2–5 days earlier heading across three seasons. Pedigree analysis indicated that the QHD.HN-5H region in ‘Haruka Nijo’ likely originated from the Tohoku six-rowed cultivar ‘Haganemugi’ and was probably co-introduced into Kyushu cultivars together with the Barley yellow mosaic virus resistance gene rym3. Whole-genome sequencing and Gene Ontology analysis identified non-synonymous differences between ‘Haruka Nijo’ and ‘Nishinohoshi’ in five heading-related genes within the QTL region. Four of these genes shared identical genotypes between ‘Haganemugi’ and ‘Haruka Nijo’, supporting their candidacy. These findings provide new breeding tools to adapt the heading date of barley to the climate and cultivation environment.
