Construction of a high-density genetic linkage map and identification of gene controlling resistance to cucumber mosaic virus in Luffa cylindrica (L.) Roem. based on specific length amplified fragment sequencing.

Luffa cylindrica L. is a cash crop which has important health, medicinal and industrial value, but no high saturation genetic map has been constructed owing to a lack of efficient markers. Furthermore, no genes were reportedly responsible for CMV resistance in Luffa spp. Specific length amplified fragment sequencing (SLAF-seq) is a valuable tool for large-scale discovery of markers and genetic mapping. The present study reported the construction of a high-density genetic map and the mapping of CMV resistant genes by using an F population of 130 individuals and their two inbred line parents. A total of 271.01 Mb pair-end reads were generated. 100,077 high-quality SLAFs were detected, and 7404 of them were polymorphic. Finally, 3701 of the polymorphic markers were selected for genetic map construction, and 13 linkage groups were generated. The map spanned 1518.56 cM with an average distance of 0.41 cM between adjacent markers. Based on the newly constructed high-density map, one gene located on chromosome 1 (100.072-100.457 cM) was identified to regulate CMV resistance in L. cylindrica. A gag-polypeptide of LTR copia-type retrotransposon was predicted as the candidate gene responsible for CMV resistance in L. cylindrica. The high-density genetic map and the CMV resistant gene mapped and predicted in this study will be useful in future research.