Marker-Assisted Forward Breeding Approach to Simultaneously Introgress Multiple Value-Added Traits While Improving Agronomic Performance.

Previously we optimized a marker-assisted background selection (MABS)-based approach to transfer a value added gene in two backcrosses, while recovering > 97% of the recurrent parent genome (RPG). Here we combined MABS and forward breeding approaches to introgress value added traits while improving agronomic performance of a wheat variety. As an example, two mutations in the ALS (acetolactate synthase) gene located on 6B and 6D chromosomes providing imidazolinone (IMI) herbicide tolerance (‘Clearfield’ technology) were transferred to a popular wheat cultivar Eltan. About 1,600 backcross (BC₁) plants were screened phenotypically by spraying with imazamox herbicide and 378 tolerant plants were evaluated using our previously optimized four-step MABS approach. Selected seven BC₁ plants were used to develop a BC₂ population of 1,400 plants and the selection procedure was repeated. About 100 plants from each of the selected 17 BC₂ plants were evaluated for various agronomic traits including single-plant yield, single plant quality test, homozygous plant two ALS gene mutations and selected by MABS. Solvent retention capacity (SRC) test was optimized using single-plant seed to select plants with optimal flour quality. Selected 12 plants were evaluated in the field. Two of these lines showing the highest RPG and other indicators of agronomic and quality parameters those were evaluated under WSU variety testing program. After three-years of testing, the two lines were released as two-gene Clearfield wheat varieties (Curiosity CL+ and Mela CL+). Curiosity CL+ and Mela CL+ have high yield potential, excellent snow mold resistance. Both varieties have better stripe rust resistance than the recurrent parent as well as currently grown Clearfield varieties in Pacific Northwest. Low flour ash content and wide cookie-diameter of Mela CL+ makes it slightly better than Curiosity CL+ that is similar to other leading varieties grown in Washington State. Sponge cake quality of these varieties is superior to check.