Identification and Fine Mapping of SiDWARF3 (D3), a Pleiotropic Locus Controlling Environment‐Independent Dwarfism in Foxtail Millet

The dwarfing of crop species could enhance lodging resistance in elite cultivars and thus increase cereal grain yields. Foxtail millet [ Setaria italica (L.) P. Beauv.] is an ancient grain crop originating from China, and it served as staple food during the development of agricultural‐based civilization in South and East Asia, where it is still grown today. Breeding for dwarfism of foxtail millet has great potential in fulfilling the food needs of an increasing world population. This study was undertaken to characterize an ethyl methanesulfonate‐induced dwarf mutant of foxtail millet ( Sidwarf3 ) derived from ‘Yugu1’. The dwarf character of the mutant was latitude independent. The mutant had fewer and shorter internodes because of smaller cells compared with the wild‐type. Furthermore, the mutant showed increased seed length and panicle tightness; however, it exhibited decreased drought tolerance. Endogenous accumulations of gibberellin, auxin, brassinosteroid, abscisic acid, and zeatin‐riboside in the mutant were changed at the jointing and heading stages of the growth period, and the plant height of Sidwarf3 could not be fully restored by applying gradient concentrations (0–5 × 10 −4 M) of gibberellic acid solution. Using combined map‐based approaches and a MutMap single‐nucleotide polymorphism index analysis, the dwarfing gene D3 was mapped to chromosome 8 and located in a genomic interval spanning 296.7 kb, which annotated 20 candidate genes for further investigation. This study provides essential information for the molecular breeding of lodging‐resistant foxtail millet cultivars through an ethyl methanesulfonate‐induced mutation approach.