Email: Zhangchen Zhao, zhaozhangchen@nwafu.edu.cn; Yin-Gang Hu, huyingang@nwafu.edu.cn

Wheat is an important food crop in the world. Lodging resistance is one of the key traits for achieving maximum yield in wheat breeding. The current production is mainly based on the dwarf genes Rht1 and Rht2, with a relatively single genetic background. Therefore, it is very important to map the new wheat dwarf gene Rht15 and clarify its genetic effects.

The F2 population was obtained by crossing the Rht15 donor parent durum wheat "Durox" (Rht15) with the tall durum wheat "Langdon" (Does not contain any dwarf genes). The recombinant was screened by previously developed molecular markers. Through the BSA strategy combined with 660K SNP chip and RNA-Seq analysis, and wheat whole genome re-sequencing technology, the homozygous differential SNPs and deletion insertion fragments between the tall and dwarf parents-lines were screened, and specific KASP markers and Indel markers were screened and developed to map the Rht15.

Based on the phenotypic and genotypic data analysis of the F2 individual and recombination, the dwarf gene Rht15 is located between markers 6A085 and 6A101 of chromosome 6A. In addition, the effects of Rht15 on plant height, internode characteristics, lodging resistance, yield components and quality traits were evaluated by the Rht15 dwarf and tall F3:4, F4:5 and F5:6 lines. Rht15 significantly reduced plant height by 31.5 % on average by shortening the cell length.

Furthermore, the diameter and wall thickness of internodes were significantly increased by Rht15, which decreased the height center of gravity (35.4 %), increased the mechanical strength of the basal internode (41.8 %), and finally improved the lodging resistance index (153.7 %). Rht15 reduced biomass plant−1 (-13.7 %), 1000-kernel weight (-12.9 %), grain number per spike (-2.3 %) and grain yield plant−1 (-10.3 %).

However, Rht15 increased the grain protein content (8.7 %), wet gluten content (9.2 %) and starch content (2.3 %). Nonetheless, Rht15 has opened up an opportunity as an alternative dwarfing gene in wheat breeding and improvement.