Characterization of a novel reduced height gene (Rht23) regulating panicle morphology and plant architecture in bread wheat

Plant height and spikelet density are important agronomic traits related to plant architecture and grain yield in wheat. The development of wheat mutants not only provided new genetic resources for wheat improvement, but also facilitated our understanding of the regulation of these traits at the molecular level. Here, we report the identification of a dwarf mutant with a compact spike. NAUH164, produced from ethyl methyl sulfonate treatment of wheat variety Sumai 3, has reduced plant height and shortened spike length. Microscopic observations showed that the mutant has an atypical vascular bundle arrangement and overall smaller cell volumes. Sensitivity of seedlings to exogenous gibberellin was not changed, and plant height was not restored to the level of the wildtype. Dwarfness and compact spike were controlled by a single dominant gene that was designated Rht23, which was mapped 4.7 cM distal to SSR marker Gdm63 and 11.1 cM proximal to Barc110 on chromosome 5DL. Comparative sequence analysis of the co-linear regions in common wheat and Aegilops taushii indicated that Rht23 occurs in a physical interval of 8.5 Mb.