Genetic introgression from Glycine tomentella to soybean to increase seed yield.

摘要

Commercial soybean [Glycine max (L.) Merr.] breeding in the U.S. currently relies on a narrow genetic base in which more than half of the genetic contribution, calculated by pedigree analysis, comes from only 5 ancestral lines. For decades, but more intensely in recent years, efforts have been made to incorporate exotic soybean germplasm into the breeding pool. G. tomentella (2n = 78), native to Australia, is a perennial relative in the tertiary gene pool of soybean. Although G. tomentella has been shown to have high levels of resistance to several diseases, including soybean rust and soybean cyst nematode, no effort has been devoted to utilizing this species to increase seed yield. The objectives of this research are to identify high yielding lines derived from backcrosses between the cultivar Dwight and G. tomentella PI 441001 (2n = 78), and to determine the genetic contribution of PI 441001 to these lines. PI 441001 was crossed to Dwight and immature seed rescue was used to produce a sterile F1 plant. Amphidiploid plants (2n = 118) were produced by treating the F 1 hybrid with colchicine. Amphidiploid plants were backcrossed to Dwight to obtain BC1 plants. A series of backcrosses were made with seven different BC2 plants to obtain BC3, BC4, BC5, and BC6 lines with 2n = 40 chromosomes. Preliminary yield testing of inbred lines from these crosses was used to select 180 lines in maturity groups (MG) II, III, and IV. Yield and other agronomic data were collected in two replication tests at six to eight locations in Ohio, Illinois, Missouri and Nebraska in 2013 and 2014. These data identified experimental lines in all three MGs that are significantly higher yielding than the recurrent parent. All experimental and parental lines were genotyped using genotyping by sequencing. G. tomentella introgressions were tested for associations with time of flowering and maturity, height, lodging, and yield. Significant associations between G. tomentella single nucleotide polymorphism introgressions and all phenotypic traits were identified. On average, 3.9, 2.5, 2.5, and 3% G. tomentella alleles were introgressed into BC3, BC4, BC5, and BC 6 derived lines, respectively.