Genetic linkage map construction and quantitative trait loci mapping of agronomic traits in Gloeostereum incarnatum

Gloeostereum incarnatum is an edible medicinal mushroom widely grown in China. Using the whole genome of G. incarnatum, simple sequence repeat (SSR) markers were developed and synthetic primers were designed to construct its first genetic linkage map. The 1,048.6 cm map is composed of 10 linkage groups and contains 183 SSR markers. In total, 112 genome assembly sequences were anchored, representing 16.43 Mb and covering 46.41% of the genome. Selfing populations were used for quantitative trait loci (QTL) targeting, and the composite interval mapping method was used to co-localize the mycelium growth rate (potato dextrose agar and sawdust), growth period, yield and fruiting body length, and width and thickness. The 14 QTLs of agronomic traits had LOD values of 3.20-6.51 and contribution rates of 2.22-13.18%. No linkage relationship was found between the mycelium growth rate and the growth period, but a linkage relationship was observed among the length, width and thickness of the fruiting bodies. Using NCBI's BLAST alignment, the genomic sequences corresponding to the QTL regions were compared, and a TPR-like protein candidate gene was selected. Using whole-genome data, 138 candidate genes were found in four sequence fragments of two SSR markers located in the same scaffold. The genetic map and QTLs established in this study will aid in developing selective markers for agronomic traits and identifying corresponding genes, thereby providing a scientific basis for the further gene mapping of quantitative traits and the marker-assisted selection of functional genes in G. incarnatum breeding programs.