Dwarfing effect associated with the threshability gene Q on wheat chromosome 5A

A dwarfing effect of the 44.1 cM chromosomal region between the threshability gene Q and Xfba068 on the long arm of hexaploid wheat chromosome 5A has been reported. To clarify whether Q or its adjacent region is responsible for regulating culm elongation, two precise genetic stocks of near-isogenic lines (NIL), a single chromosome substitution line, 'Chinese Spring' (CS; 'Cappelle-Desprez' 5A) (NIL-Q) and a single chromosome recombinant substitution line (NIL-q) were used. The target segment of NIL-q included the q allele and QEet.ocs-5A.1, an earliness per se gene, from spelt wheat in the CS genetic background. They were grown under 16-h day length with and/or without vernalization treatment. Being independent of heading date, NIL-Q showed shorter elongation in lower internodes and decreased internode differentiation in comparison with NIL-q. The culm-length reduction associated with Q was confirmed in the recombinant F-5 population derived from the cross between NIL-Q and NIL-q. Vernalization promotion had a tendency to reduce this dwarfing effect.