Genomic-assisted Pyramiding of Semi-dwarfism and Micronutrient-enrichment Traits for Developing Climate-smart Wheat (Triticum aestivum L.)

Abstract

The identification of this new dwarfing gene and its linked markers will greatly facilitate its utilization in wheat high-yield breeding for reducing plant height. The tall wheat variety C-306, renowned for its chapatti-making quality, suffers from lodging under high-input conditions, limiting its yield potential. This study aimed to improve C-306 by introgressing the semi-dwarfing gene Rht1 using marker-assisted selection (MAS) and to evaluate the subsequent effects on agronomic performance and grain micronutrient content. C-306 was used as the recurrent parent in backcrosses with three semi-dwarf donor varieties (WH 1105, DBW 14, HD 2932). Foreground selection for the Rht1 gene was performed using gene-specific PCR markers. The resulting near-isogenic lines (NILs) were evaluated for morphological traits, yield components, and grain Fe/Zn concentrations via atomic absorption spectroscopy. The marker-assisted introgression successfully reduced plant height in the C-306 background. Correlation analysis revealed a moderate positive relationship between plant height and biomass (r = 0.55) and yield (r ≈ 0.40), highlighting a critical breeding trade-off. Crucially, grain Fe and Zn concentrations were positively correlated (r = 0.44) and showed a modest positive association with yield, demonstrating that biofortification can be pursued without a significant yield penalty. Furthermore, total biomass was identified as the primary driver of economic yield (r = 0.87). This study establishes an effective framework for combining MAS with phenotypic analysis to improve traditional cultivars, providing valuable genetic resources for developing shorter, lodging-resistant, and nutritionally enhanced wheat varieties.