Genetic mapping and isolation of Rht28, a locus on wheat chromosome arm 2AL affecting plant height, grain size, and grain weight.

Key message: We identified Rht28, a novel dwarf gene on the wheat chromosome arm 2AL, and investigated its effect on important agronomic traits. The genetic dissection of wheat plant height (PH) and the identification of new dwarf or semi-dwarf genes will help breeders to improve yield potential. In this study, QPh-2A.2, a newly discovered locus controlling PH and explaining 7.29%-14.61% of the phenotypic variation across ten environments, was identified using a recombinant inbred line (RIL) population derived from the cross Yanda 1817 × Beinong 6 through a previously constructed single nucleotide polymorphism (SNP) genetic linkage map. To confirm the stability and effect of QPh-2A.2, 22 tightly linked markers were developed based on the released Chinese Spring (CS) reference genome sequence, and a high-density genetic linkage map of the target locus was constructed. QPh-2A.2 is a newly discovered locus controlling PH in wheat, which is temporarily designated Rht28. Additionally, Rht28 was found to have significant effects on thousand-grain weight, grain width, grain thickness, and grain weight per spike, as evaluated in the RIL population, while other agronomic traits related to flag leaf and spike traits were not significantly affected. Moreover, using a large segregating population and extensive progeny tests, we mapped Rht28 within a 3.17-Mb physical region between the markers WBUA4036 and WBUA4413 on the long arm of chromosome 2A. This targeted region contains 51 annotated genes according to CS v2.1 reference genome sequence, and two of these were speculated to be candidates for Rht28. Exploring new dwarf genes is a vital route to breed lodging-resistant wheat cultivars. This study also provides important information for Rht28 marker-assisted selection in wheat breeding programs.