Effects of the GA-responsive dwarfing gene Rht18 from tetraploid wheat on agronomic traits of common wheat

Abstract

To evaluate the potential use of GA-responsive dwarfing gene Rht18 in common wheat breeding programs, the effects of Rht18 from tetraploid wheat on plant height, coleoptile length, seedling root characters, and yield components were investigated and compared in field experiments using F3:4 and F4:5 hexaploid dwarfing lines with Rht18 derived from three crosses between its tetraploid donor Icaro (Rht18) and three tall Chinese winter wheat cultivars, Xifeng20, Fengchan3 and Jinmai47. The results showed that Rht18 significantly reduced plant height by 25.0%, 12.4% and 15.5%, on average, in the dwarf lines of Xifeng20, Fengchan3 and Jinmai47 compared with their tall parents, respectively. There were no adverse effects of Rht18 on coleoptile length and seedling root characters except for a reduction of 1.1cm (−17.3%) in coleoptile length observed in the dwarf lines of Jinmai47. The partitioning of dry matter to ears at anthesis was increased in the dwarf lines compared with their tall parents in all three populations. The effects of Rht18 on yield components varied with the genetic background of the tall parents used. For the F4:5 dwarf lines of Xifeng20, spikelet number spike−1 was increased by 4.8%, and grain number spike−1 was significantly increased by 9.2% on average in the Rht18 dwarf lines, but 1000-kernel weight was significantly decreased by 14.9%. In contrast, there was decreased spikelet number spike−1 (−8.6% and −21.7%) and grain number spike−1 (−4.9% and −2.0%) but increased 1000-kernel weight (4.0% and 7.7%) observed in the Rht18 dwarf lines of both Fengchan3 and Jinmai47, respectively. Biomass plant−1 and grain yield plant−1 were decreased in the Rht18 dwarf lines of all three crosses but the harvest index was increased compared to the tall parents. In general, although the effects of Rht18 on plant height and yield varied with the genetic background of the tall parents used, the moderate reduction on plant height, increased harvest index and no adverse effects on seedling vigor associated with Rht18 all indicate that the GA-responsive dwarfing gene Rht18 could be used to improve wheat performance in breeding programs but that attention should be paid to the selection of the most suitable adapted parents. Some good common wheat lines with Rht18 have been created and could be used in breeding programs.