Breeding Value of Primary Synthetic Wheat Genotypes for Grain Yield

Abstract

To introduce new genetic diversity into the bread wheat gene pool from its progenitor, Aegilops tauschii (Coss.) Schmalh, 33 primary synthetic hexaploid wheat genotypes (SYN) were crossed to 20 spring bread wheat (BW) cultivars at the International Wheat and Maize Improvement Center. Modified single seed descent was used to develop 97 populations with 50 individuals per population using first back-cross, biparental, and three-way crosses. Individuals from each cross were selected for short stature, early heading, flowering and maturity, minimal lodging, and free threshing. Yield trials were conducted under irrigated, drought, and heat-stress conditions from 2011 to 2014 in Ciudad Obregon, Mexico. Genomic estimated breeding values (GEBVs) of parents and synthetic derived lines (SDLs) were estimated using a genomic best linear unbiased prediction (GBLUP) model with markers in each trial. In each environment, there were SDLs that had higher GEBVs than their recurrent BW parent for yield. The GEBVs of BW parents for yield ranged from -0.32 in heat to 1.40 in irrigated trials. The range of the SYN parent GEBVs for yield was from -2.69 in the irrigated to 0.26 in the heat trials and were mostly negative across environments. The contribution of the SYN parents to improved grain yield of the SDLs was highest under heat stress, with an average GEBV for the top 10% of the SDLs of 0.55 while the weighted average GEBV of their corresponding recurrent BW parents was 0.26. Using the pedigree-based model, the accuracy of genomic prediction for yield was 0.42, 0.43, and 0.49 in the drought, heat and irrigated trials, respectively, while for the marker-based model these values were 0.43, 0.44, and 0.55. The SYN parents introduced novel diversity into the wheat gene pool. Higher GEBVs of progenies were due to introgression and retention of some positive alleles from SYN parents.

Gains through selection for grain yield in a winter wheat breeding program

“…In the context of selecting new parental lines based on GEBV alone, it was recently observed that selecting for high FHB resistance in winter wheat was not that reliable, as only 19% of the lines (9 out of 47) correctly predicted by GEBV belong to the best 10% for FHB resistance [35]. In another study, negative GEBV for yield were observed for synthetic hexaploid spring bread wheat lines evaluated across heat and irrigated environments [36]. Selection for drought tolerance in maize using GEBV, in contrast, has resulted in rapid genetic gains and positive selection responses through using molecular markers associated with yield under drought stress [37].…”

Long non-coding RNAs in wild wheat progenitors

“…tauschii) to improve modern wheat; i.e. grain yield (Jafarzadeh et al 2016). These advanced breeding strategies, coupled with the benefit derived from the wheat genomics era (Uauy 2017), are essential requirements for ensuring a rapid return to the applied wheat research programs, which cannot do without the deep characterization of the functional intergenic space of the genome.…”

Genomic innovation for crop improvement

“…In wheat, new polyploids made by crossing different goatgrass variants with tetraploid wheats have captured a wide range of useful genetic variation. These 'synthetic' wheats are crossed into elite wheat lines and then backcrossed to fix desired phenotypes 64 . A durum wheat (pasta wheat; Triticum durum) line that maintains high yields when grown in saline soil was created by introgressing a region of the einkorn wheat (T. monococcum) genome (a diploid progenitor of tetraploid durum wheat and hexaploid bread wheat) that contains a sodium exclusion pump 65 .…”