Identification of a QTL for Setaria italica bristle length using QTL-seq

Long bristles facilitate seed dispersal and protect seeds from herbivores. Early domesticated Setaria italica cultivars had long bristles, but most of the modern cultivars have short bristles. Little is known about the molecular regulatory mechanisms underlying the bristle length trait of S. italica. We generated a segregating population derived from a cross between a long bristle (Z-45) and a short bristle (Z-47) cultivars. A quantitative trait locus (QTL) was identified at 35–40 Mb on chromosome 1 using QTL-seq. In addition, we found that 351-bp transposable element insertion in the Seita.1G316900 promoter was linked to the short bristle trait, which can be used in marker-assisted selection in crop breeding. In addition, some evidences were also found for Seita.1G338900 to play a role in regulation of bristle length. In summary, we hypothesize that Seita.1G316900 and Seita.1G338900 could be candidate genes for bristle length in S. italica. But further functional analysis of these genes are required.