Genetic effects of dwarfing gene Rht-5 on agronomic traits in common wheat (Triticum aestivum L.) and QTL analysis on its linked traits

- Rht5 has a strong effect in reducing plant height.
- Grain weight reduction by Rht5 could be improved during selection.
- Rht5 is associated with quantitative trait loci.
- The combination Rht5/Rht8 could improve heading date and maturity.

In order to evaluate the genetic effects of Rht-5 dwarfing gene on agronomic traits in common wheat, F2 population and 32 F2:3 lines derived from the cross between Jinmai47 (rht-5) and Marfed M (Rht-5) along with the two parents were grown in the winter wheat growing seasons of 2011-2012 and 2012-2013, respectively. The F2 population formed the mapping population and their phenotypic and genotypic data were merged for QTL mapping. The dwarf and tall individuals in the F2 population were selected to compose the F2:3 lines. Analysis of variance in the F2 population and F2:3 lines showed highly significant differences among individuals or lines for all of traits studied, except for biomass and grain yield. In general, in the background of Jinmai47, dwarfing gene Rht-5 was associated with a plant height reduction of 25.84%, delaying heading date by 1 day, increasing the number of fertile tillers plant−1 by 37.39%, while reducing the number of spikelets spike−1 and number of grains spike−1 by 8.07% and 22.31%, respectively. Individuals with earlier heading date, longer spikes, more spikelets spike−1, and more grains spike−1 could be observed in the dwarf lines when compared to the dwarf parent. Plant height showed highly positive and significant correlation with peduncle length (0.88), spike length (0.80), number of spikelets spike−1 (0.63), number of grains spike−1 (0.64), biomass (0.47), grain yield (0.56) and harvest index (0.37), whereas it had negative and highly significant correlation with the number of fertile tillers plant−1 (−0.64). A partial chromosomal linkage map was constructed with three polymorphic markers based on their genotypes in the F2 population. Using composite interval mapping (CIM) analysis, four QTLs were detected for plant height, heading date, peduncle length and number of grains spike−1 and accounted for up to 11.82%, 8.02%, 10.32% and 15.65% of the phenotypic variation, respectively. The results of the current study could be useful for proper use of Rht-5 dwarfing gene in breeding programs to improve lodging tolerance, yield potential in wheat and increase efficiency of marker assisted selection for agronomic traits.