Agronomic Trait Analysis and Genetic Mapping of a New Wheat Semidwarf Gene Rht-SN33d

Plant height is a key agronomic trait that is closely to the plant morphology and lodging resistance in wheat. However, at present, the few dwarf genes widely used in wheat breeding have narrowed wheat genetic diversity. In this study, we selected a semi-dwarf wheat mutant dwarf33 that exhibits decreased plant height with little serious negative impact on other agronomic traits. Genetic analysis and mutant gene mapping indicated that dwarf33 contains a new recessive semi-dwarf gene Rht-SN33d, which was mapped into ~1.3 Mb interval on the 3DL chromosome. The gibberellin metabolism-related gene TraesCS3D02G542800, which encodes gibberellin 2-beta-dioxygenase, is considered a potential candidate gene of Rht-SN33d. Rht-SN33d reduced plant height by approximately 22.4% in mutant dwarf33. Further study revealed that shorter stem cell length may be the main factor causing plant height decrease. In addition, the coleoptile length of dwarf33 was just 9.3% shorter than that of wild-type Shaannong33. These results will help to expand our understanding of new mechanisms of wheat height regulation, and obtain new germplasm for wheat improvement.