QTL mapping utilizing F_2:3 linkage mapping populations reveals regions of chromosomes 2 and 6 are significantly associated with root width in carrot

This study aimed to map quantitative trait loci (QTL) associated with carrot root width using linkage mapping. Two bi-parental populations derived from the cross of carrot inbred lines L1408 and W133, followed by two generations of selfing, were combined resulting in a total of 123 F3 individuals grown in a randomized complete block design in the years 2020 and 2021 in Randolph, Wisconsin, USA. Phenotyping of carrot root traits was performed using a digital imaging pipeline, and genotyping was done using genotyping-by-sequencing (GBS). A total of 3,953 high quality single nucleotide polymorphisms (SNPs) markers were retained. A genetic map was constructed, and composite interval mapping was performed. The results showed that three QTLs were significantly associated with carrot root width on chromosomes 2 and 6 and explain between 10 and 18% of the phenotypic variance. The results here expand the current understanding of the genetic control of carrot root shape traits.