Extending Genetic Diversity of the Cultivated Wheat By Synthetic Hexaploid Wheats for Grain Yield

To introduce novel genetic diversity into the bread wheat gene pool from its progenitor, Aegilops tauschii,20 CIMMYT spring bread wheat (BWs) were crossed to 33 primary synthetic hexaploid wheats (SYNs) in 2008 in CIMMYT, Mexico. Populations were developed through single seed decent by backcross, bi-parental and three-way crosses. Selection of progeny was based on plant height, days to heading and maturity. Yield trials were conducted under irrigated, drought and heat-stress conditions from 2011 to 2014 in Cuidad Obregon, Mexico. DArT-seq GBS markers was used for genotyping. Genomic estimated breeding values (GEBVs) of synthetic derived lines (SDLs) and parents were estimated using GBLUP model with markers. The genetic variation of parents and SDLs was assessed in A, B and D genomes using polymorphism information content (PIC). Mean PIC values for SYNs and BWs were similar in A and B genomes (0.23) while they were 0.37 for SYNs and 0.05 for BWs in D genome. The overall mean PIC was 0.18, 0.28 and 0.31 for BWs, SYNs and SDLs, respetivelly. Average GEBVs (AGEBVs) of grain yield were 0.9 for top 10% of populations (Top10%) and 0.94 for recurrent BWs (RBWs) under irrigated condition. They were 0.34 and 0.30 for Top10% and RBWs under drought stress, respectively. Under heat stress, AGEBVs were 0.55 and 0.26 for Top10% and RBWs, respectively. The synthetic wheats extende diversity of cultivated wheat and increase GEBVs of progenies by introgression of positive alleles to the wheat gene pool.

Keywords: genetic diversity, synthetic wheats, genomic estimated breeding value.