Enhancing oil content is an important breeding objective in peanut. High-resolution mapping of quantitative trait loci (QTLs) with linked markers could facilitate marker-assisted selection in breeding for target traits. In the present study, a recombined inbred line population (Xuhua 13×Zhonghua 6) was used to construct a genetic map based on double-digest restriction-site-associated DNA sequencing (ddRAD-seq). The resulting high-density genetic map contained 2595 loci, and spanned a length of 2465.62 cM, with an average distance of 0.95 cM/locus. Seven QTLs for oil content were identifed on fve linkage groups, including the major and stable QTL qOCA08.1 on chromosome A08 with 10.14–27.19% phenotypic variation explained. The physical interval of qOCA08.1 was further delimited to a~0.8-Mb genomic region where two genes afecting oil synthesis had been annotated. The marker SNPOCA08 was developed targeting the SNP loci associated with oil content and validated in peanut cultivars with diverse oil contents. The major and stable QTL identifed in the present study could be further dissected for gene discovery. Furthermore, the tightly linked marker for oil content would be useful in marker-assisted breeding in peanut.
Figure 2: Overview of the genetic map constructed using SNP markers. a Distribution of SNP markers on 20 linkage groups. Black bars denote SNP markers. The linkage group numbers are shown on the x-axis. b Collinearity analysis between the genetic map and the physical map. a01–a10 and b01–b10 represent the 20 linkage groups. A01–A10 and B01–B10 indicate physical maps of Arachis duranensis and Arachis ipaensis, respectively