A High-Density Genetic Linkage Map and QTL Analysis of Drought-Related Traits in St. Augstinegrass Using Genotyping-By-Sequencing.

St. Augustinegrass (Stenotaphrum secundatum) is a warm-season grass species commonly utilized as turf in the southeastern US. To determine the genetic basis of drought-related traits in St. Augustinegrass, we used a “Raleigh” x “Seville” pseudo-F2 mapping population to construct a high-density linkage map from 2,871 single-nucleotide polymorphisms (SNPs) and 85 SSR markers. A total of 2,956 markers were assigned to nine linkage groups. The genetic linkage map had a total length of 1244.25 cM, with an average of 0.42 cM between markers. The population was evaluated for drought tolerance both under greenhouse and field conditions. Data was collected on root length and dry weight, leaf relative water content, and electrolyte leakage. Significant variation was observed among parents and progeny. Twenty four putative QTL were identified on six linkage groups. Bioinformatics analysis revealed potential genes located in these QTL regions were involved in drought response in diverse pathways. The QTL regions and associated molecular markers identified in this study could be used to improve the drought tolerance breeding in St. Augustinegrass.