Tapping the genetic diversity of landraces in allogamous crops with doubled haploid lines: a case study from European flint maize

Key message Using landraces for broadening the genetic base of elite maize germplasm is hampered by heterogeneity and high genetic load. Production of DH line libraries can help to overcome these problems . Abstract Landraces of maize ( Zea mays L.) represent a huge reservoir of genetic diversity largely untapped by breeders. Genetic heterogeneity and a high genetic load hamper their use in hybrid breeding. Production of doubled haploid line libraries (DHL) by the in vivo haploid induction method promises to overcome these problems. To test this hypothesis, we compared the line per se performance of 389 doubled haploid (DH) lines across six DHL produced from European flint landraces with that of four flint founder lines (FFL) and 53 elite flint lines (EFL) for 16 agronomic traits evaluated in four locations. The genotypic variance ( σ _G^2 ) within DHL was generally much larger than that among DHL and exceeded also σ _G^2 of the EFL. For most traits, the means and σ _G^2 differed considerably among the DHL, resulting in different expected selection gains. Mean grain yield of the EFL was 25 and 62