High-density linkage maps for Citrus sunki and Poncirus trifoliata using DArTseq markers

The construction of a high-resolution genetic map of citrus would be of great value to breeders and to associate genomic regions with characteristics of agronomic interest. Here, we describe a novel high-resolution map of citrus using a population derived from a controlled cross between Citrus sunki (female parent) and Poncirus trifoliata (male parent). The genetic linkage maps were constructed using DArTseq markers and a pseudo-testcross strategy; only markers showing the expected segregation ratio were considered. To investigate synteny, all markers from both linkage maps were aligned with the genome of Citrus sinensis . The C . sunki map has a total of 2778 molecular markers and a size of 2446.6 cM, distributed across ten linkage groups. The map of P . trifoliata was built with 3084 markers distributed in a total of nine linkage groups, with a total size of 2411.6 cM. These maps are the most saturated linkage maps available for C . sunki and P . trifoliata and have high genomic coverage. We also demonstrated that the maps reported here are closely related to the reference genome of C . sinensis .