Production of synthetic wheat lines to exploit the genetic diversity of emmer wheat and D genome containing Aegilops species in wheat breeding

Abstract

Due to the accumulation of various useful traits over evolutionary time, emmer wheat (Triticum turgidum subsp. dicoccum and dicoccoides, 2n = 4x = 28; AABB), durum wheat (T. turgidum subsp. durum, 2n = 4x = 28; AABB), T. timopheevii (2n = 4x = 28; AAGG) and D genome containing Aegilops species offer excellent sources of novel variation for the improvement of bread wheat (T. aestivum L., AABBDD). Here, we made 192 different cross combinations between diverse genotypes of wheat and Aegilops species including emmer wheat × Ae. tauschii (2n = DD or DDDD), durum wheat × Ae. tauschii, T. timopheevii × Ae. tauschii, Ae. crassa × durum wheat, Ae. cylindrica × durum wheat and Ae. ventricosa × durum wheat in the field over three successive years. We successfully recovered 56 different synthetic hexaploid and octaploid F₂ lines with AABBDD, AABBDDDD, AAGGDD, D¹D¹X^crX^crAABB, D^cD^cC^cC^cAABB and D^vD^vN^vN^vAABB genomes via in vitro rescue of F₁ embryos and spontaneous production of F₂ seeds on the F_l plants. Cytogenetic analysis of F₂ lines showed that the produced synthetic wheat lines were generally promising stable amphiploids. Contribution of D genome bearing Aegilops and the less-investigated emmer wheat genotypes as parents in the crosses resulted in synthetic amphiploids which are a valuable resource for bread wheat breeding.