Identification of Rht1 for plant height reduction in two wheat mutants and the effects on yield components

Abstract

Plant height determines lodging resistance and is closely linked to yield stability in wheat. In this study, we identified two semi-dwarf wheat mutants, designated je0370 and je0344, using the winter wheat cultivar Jing411 as the wild type (WT). Field experiments revealed that the plant height of these two mutants was significantly lower than that of the WT. In contrast, the thousand-grain weight was significantly higher in je0370 but lower in je0344 compared to the WT. Bulk Segregant Analysis (BSA) based on exome capture sequencing indicated that the gene responsible for height reduction is located on chromosome 4B. Further genetic linkage analysis mapped the dwarf gene to the interval of 29.26-48.61 Mb on chromosome 4B, corresponding to a genetic distance of 10.79 cM. This region encompasses the Rht1 gene; we subsequently sequenced the Rht1 gene in je0370 and je0344 and identified a C-T mutation at position 190 bp, resulting in a truncation of the DELLA domain in both mutants. Further analysis using Cleaved Amplified Polymorphic Sequences (CAPS) markers in F₂ populations demonstrated that plants with homozygous Rht1 mutations exhibited significantly reduced plant height and thousand-grain weight, while heterozygous plants displayed intermediate effects. However, the mutation did not significantly affect spikelet number, effective spike number, or spike length. These findings conclusively demonstrate that the Rht1 mutation is responsible for plant dwarfism and reduced grain weight, without substantial impacts on other yield components. This study provides invaluable insights into the utilization of Rht1 in wheat breeding.

Keywords: Dwarf mutant; Plant height; Thousand-grain weight; Wheat; Yield-related traits.