The semi-dwarfing gene Rht-dp from dwarf Polish wheat (Triticum polonicum L.) is the “Green Revolution” gene Rht-B1b

Abstract Background: The wheat dwarfing gene increases lodging resistance, the grain number per spike and harvest index. Dwarf Polish wheat ( Triticum polonicum L., 2n = 4x = 28, AABB, DPW), initially collected from Tulufan, Xinjiang, China, carries a semi-dwarfing gene Rht-dp on chromosome 4BS. However, Rht-dp and its dwarfing mechanism are unknown. Results: Homologous cloning and fine mapping revealed that Rht-dp is the ‘Green Revolution’ gene Rht-B1b . A haplotype analysis in 59 tetraploid wheat accessions showed that Rht-B1b was only present in T. polonicum . Transcriptomic analysis of two pairs of near-isogenic lines (NILs) of DPW×Tall Polish wheat ( Triticum polonicum L., 2n = 4x = 28, AABB, TPW) revealed 41 differentially expressed genes (DEGs) as potential dwarfism-related genes. Among them, 28 functionally annotated DEGs were classed into five sub-groups: hormone-related signalling transduction genes, transcription factor genes, cell wall structure-related genes, reactive oxygen-related genes, and nitrogen regulation-related genes. Conclusions: These results indicated that Rht-dp is Rht-B1b , which regulates pathways related to hormones, reactive oxygen species, and nitrogen assimilation to modify the cell wall structure, and then limits cell wall loosening and inhibits cell elongation, thereby causing dwarfism in DPW.