Genetic mapping of QTL for three root-related traits in wheat (Triticum aestivum)

Abstract

A well-developed root system plays a positive role in wheat yield. Here, we identified quantitative trait loci (QTL) for total root length (TRL), root average diameter (RD) and number of root tips (RTN) based on the previously developed genetic map of a recombinant inbred line (RIL) population in bread wheat and phenotype data from two individual trials. A stable and major QTL, Qtrl-AS-5A for TRL was detected explaining 17.19 to 17.78% of the phenotypic variation. It was physically located at 680.66-683.25 Mb (∼2.59 Mb interval) on chromosome arm 5AL. Two stably expressed QTLs for RD, Qrd-AS-4A and Qrd-AS-6B, were identified. The phenotype variances explained for them were between 5.11 to 5.43% and 17.42 to 22.40%, respectively. They were physically located at 621.74 Mb-621.93 Mb (∼0.19 Mb) on 4AL and 624.01 − 624.78 Mb (∼0.77 Mb) on 6BL, respectively. One unstably expressed QTL for RN was identified only. Genetic analysis suggested that the two major and stably expressed QTLs, Qtrl-AS-5A and Qrd-AS-6B, were not likely associated with plant height and anthesis date. Comparison analysis indicated that they may be novel loci. Several candidate genes which were mainly expressed in roots were also obtained. Collectively, these results provided several major and stably expressed QTLs for root traits and they should have breeding potential.