Genetic Mapping of Quantitative Trait Loci (QTLs) Associated with Seminal Root Angle and Number in Three Populations of Bread Wheat (Triticum aestivum L.) with Common Parents

Drought tolerance of plants is related to their root system architecture. The architecture of a mature plant root system is closely linked to seminal root growth at the seedling stage; hence, selection for root characteristics at the seedling stage may identify genotypes better suited for drought conditions. Here, the genetics of seminal root angle and number were investigated in three doubled haploid mapping populations of wheat. All populations showed significant phenotypic variation for both traits and each demonstrated transgressive segregation. In total, 34 genomic regions were associated with seminal root traits; however, most QTLs were variable from year to year and were population specific. Considering only the results consistent across both years of experiments, five QTLs for seminal root angle were identified on chromosomes 2DS, 5BS, 6AL, 7A, and 7BS, but only the 2DS QTL appeared in two of the three populations. For the seminal root number, one QTL was identified on 4BL. Correlation analyses for seminal root angle, number, and seed weight revealed interesting relationships to consider for future research. In one population, those interactions wrongfully identified QTLs for seed weight as QTLs for seminal root traits. Our findings demonstrate that seminal root angle and number are complex traits and despite high heritability, may be more difficult to unwind than previously proposed.