Comparative mapping of fiber, protein, and mineral content QTLs in two interspecific Leymus wildrye full-sib families

Crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), and mineral content are important components of forage quality in grasses. Elevated [K]/([Ca] + [Mg]) ratios (KRAT) substantially increase the risk of grass tetany (hypomagnesemia) in grazing animals, which is a serious problem associated with some cool-season grasses. The objectives of this study were to map and compare QTLs controlling concentrations of CP, NDF, ADF, Al, B, Ca, Cl, Cu, Fe, K, Mg, Mn, Na, P, S, Si, Zn, and KRAT in two full-sib Leymus triticoides x (L. triticoides x (L. cinereus) TTC1 and TTC2 families. Significant genetic variation and QTLs were detected for all traits, with evidence of conserved QTLs for ADF (LG1a, LG5Xm, LG7a), NDF (LG7a), Ca (LG1b), CP, (LG5Xm), KRAT (LG3b, LG6b, LG7a, LG7b), Mn (LG2b, LG3b, LG4Xm), and S (LG3a) content in both TTC1 and TTC2 families. Moreover, the direction of QTL effects was the same for 13 of the 14 homologous QTLs in both families. The TTC1 and TTC2 KRAT QTLs on LG7a and LG7b were located near markers defining homoeologous relationships between the sub-genomes of allotetraploid Leymus, suggesting possible QTL homoeology. Another 88 QTLs were unique to one family or the other, but many of these clustered in genome regions common between the two families. These results will support development of new Leymus wildrye forages and help characterize genes controlling mineral uptake and fiber synthesis.