Mapping QTLs Controlling Grain and Leaf Traits in Iranian Wheat Recombinant Inbred Lines

Increasing the yield potential of wheat, as the most important grain product in the world, is undoubtedly important in solving the consequences of world hunger. The aim of this study was to identify the genomic regions controlling traits related to grains (grain length, grain width, and grain weight per spike) and leaves (flag leaf length, flag leaf width, leaf number, second leaf length, and second leaf width). This study involved a mapping population consisting of 120 recombinant inbred lines of the F8 generation of bread wheat resulting from a cross of Kohdasht (KHD) and Gonbad (GND) cultivars during and phenotyped for 2 years (2019 and 2020). The experiment was performed as an alpha lattice design. Genetic linkage map was provided using 521 polymorphic alleles of SSR (423 alleles), CBDP (21 bands), ISJ (58 bands), and SCoT (19 bands) markers. The length of the map was 3167.9 cM with an average distance of 1.6 cM between adjacent markers. In total, for 2 years, 10 quantitative trait loci (QTLs) were identified on chromosomes 1A, 1B, 3B, 3D, 4D, and 7D for 3 traits related to grain. Four QTLs explained 15% phenotypic variance and were reported as large-effect QTLs for grain length traits. Detected three and four large-effect QTLs were for leaf-related traits in 2019 and 2020, respectively. In 2019, two QTLs, qFLW-1B (flag leaf width) and qLEL-1B (second leaf length), and, in 2020, three QTLs, qFLL-1B (flag leaf length), qFLW-1B (flag leaf width), and qLEL-1B (second leaf length), were located at 166.34 cM on chromosome 1B and linked to Xgpw7577-1B. For flag leaf length, two stable QTLs (qFLL-2B and qFLL-3A) were located at 78.30 and 22.22 cM on chromosomes 2B and 3A, respectively. For flag leaf width, a stable QTL (qFLW-1B) was identified at 166.34 cM on chromosome 1B and linked to Xgpw7577-1B. For the second leaf length, QTLs qLEL-1B and qLEL-6A were stable on chromosomes 1B and 6A. The work will help to understand the genetic mechanisms of grain and leaf of wheat and lay a foundation for further marker-assisted breeding programs.

Automated summary

The aim of this study was to identify the genomic regions controlling traits related to grains and leaves in wheat. Through genotyping and phenotyping, 10 quantitative trait loci were identified for grain and leaf traits. These findings help to understand the genetic mechanisms of wheat and support marker-assisted breeding programs.