Identification of species, quantative trait loci( QTLs ) , and hybrids important for low-input biomass production and heterosis in semiarid cold-growing environments

摘要

Interspecific hybrids of tall caespitose Leymus dnereus and strongly rhizomatous Leymus triticoides display a heterotic combination of traits important for perennial grass biomass production. The objectives of this study were to: 1) compare seasonal biomass accumulation among Leymus wildrye species and hybrids relative to other large -statured perennial grasses, and 2) identify genes, QTLs, and traits associated with biomass accumulation and heterosis in full -sib mapping populations derived from two L. triticoides x L. dnereus hybrids backcrossed to one L. triticoides plant, under low -input management at two locations in semiarid cold -growing environments. Second -year biomass averages (Mg/ha SE) varied among key reference species including Festuca arundinaceae (2.1 0.4), L. triticoides (2.60.4), Panicum virgatum (3.60.6), Leymus angustus (6.38 1.0), L. dnereus (7.20. 4), Thinopyrum intermedium (8. 3 0. 9), and Thinopyrum ponticum (8. 7 0. 9). T. ponticum was significantly better than all other species tested in the first year, but L. dnereus, L. angustus, and Leymus hybrids showed the greatest second -year gains. The second -year yields of the Leymus hybrids (5.5 -7.6 0.7) were equal or greater than the L. dnereus Acc636 parental accession (5.9 0.7) , much greater than the L. triticoides Lt -F03 parent genotype (1.40.6), and competitive with the best individual entries overall. Significant QTLs were detected in the first two harvest years for both populations. The chromosome position of biomass QTLs were generally stable over years and locations, and showed correspondence with plant height, culm width, flowering, protein, and fiber QTLs. However, the location of biomass QTLs did not correspond between the TTC1 and TTC2 families.