High-density Genetic Map Construction And STPC Related QTL Mapping For Dendrobium

Dendrobium species are orchid plants with a broad range of therapeutic effects,the main active ingredients are polysaccharide,alkaloids,flavones,phenols,and benzyl.To understand the genetic basis of the dendrobe active ingredients,particularly the stem total polysaccharide contents?STPCs?,it is of paramount importance to understand the genetic basis of STPC at the whole genome level.Breeding cultivars with high-STPC,high-alkaloid,cold-resistant,or disease-resistance,are the main objectives in the Dendrobium industry.Here,we first report the high-density single-nucleotide polymorphism?SNP?integrated genetic map of Dendrobium that provides a good coverage of the Dendrobium genome,and the STPC related QTL mapping.1?An interspecific F₁ hybrid population was established by crossing the lower STPC species D.moniliforme as the female parent with the high STPC species D.officinale as the male parent?both 2n=38?.2?Two parents?D.moniliforme?×D.officinale??and their interspecific F₁hybrid population were genotyped by specific-locus amplified fragment sequencing?SLAF-seq?,leading to the identification of 7,013,400 SNPs from 1,503,626 high-quality SLAF markers.The mean sequencing depth was 168.42-fold for the female parent,158.86-fold for the male parent,and 41.91-fold for the offspring.Of the SNP markers detected,398,083 were polymorphic with sufficient quality for map construction.The final genetic map was constructed using 8,573 SNP markers,covering19 linkage groups?LGs?.The genetic map spanned 2,737.49 cM in length,with an average distance of 0.32 cM between markers.3?In total,11 quantitative trait loci?QTL?related to STPC were identified,9 of which have candidate genes within the confidence intervals of these stable QTLs based on the reference D.officinale genome sequence.In constructing the a first high-density genetic map and conducing the first STPC-related QTL mapping of Dendrobium,this study will provide a foundation for the mapping of other medicinal-related traits and provide an important reference for the molecular breeding of these Chinese herb.