Multifactorial mapping of QTL for partitioning of assimilates under drought stress in wheat (Triticum aestivum L.)

Crops' capability to store photosynthetic resources in the pre-flowering stage and successfully re-transport the stored photoassimilates in the seed-filling stage plays a significant role in the development of the final grain yield, and identifying the genetic structure of this mechanism can help breeders develop high-yielding cultivars. For this purpose, to map quantitative trait loci (QTLs) affecting assimilates partitioning in wheat under drought stress, we used 148 recombinant inbred lines derived from a cross between two winter wheat cultivars, 'YecoraRojo' and Iranian landrace (No. #49). Linkage mapping was performed using 51 retrotransposons and 177 microsatellite markers. Under normal irrigation conditions, four QTLs were identified for assimilates partitioning (R-A(2) = 7.68-13.36%), and 10 additives additive epistatic interactions (R-AA(2) = 2.08-10.47%) and 12 QTLs x QTL x environment interactions (R-AAE(2) = 0.78-17.4) were significant. Under the water deficit condition, three QTLs (R-A(2) = 7.02-7.78%) were identified, and eight additives x additive epistasis interactions (R-AA(2) = 2.44-10.9%) were significant. The mapped QTLs are located on chromosomes 4A, 6A, and 7A, indicating their critical role in controlling assimilates partitioning in wheat. The results indicate that QTLs flanked by Wmc786-5LTR.2/ISSR9.170 and Cfa2123- Gwm282 markers on the 6A and 7A chromosomes are stable under drought stress, which could be advantageous for marker-assisted selection.