The Doubled Haploid Facility is developing new haploid inducing lines for maternal haploid induction in maize. The goal is to increase not only haploid induction rates, but also to add new selectable marker for haploid identification and improved agronomical traits of the inducer lines.

The breeding program started in 2010, when we began to introgress induction ability into Midwest adapted backgrounds, to improve agronomic traits of the so far licensed inducer lines RWS and RWK (ISURF#04065). These lines use the kernel color marker R1-nj as selectable marker. Variable expression of the color marker and suppression in some genetic backgrounds made it necessary to add Pl1 as an additional selectable marker in haploid selection in a second breeding cycle. In the presence of Pl1 the hybrids have dark red roots, whereas the haploid seedlings have uncolored roots. We also added the partial dent sterility (Ga1) to our inducer lines, to allow haploid induction in popcorn backgrounds (ISURF#04099).

Hand selection of haploid seed based on the color marker is very time intensive. A new breeding cycle of haploid inducing lines has the goal to develop a high oil haploid inducing line, to allow machine sorting based on the differences in oil content between haploid and hybrid seed.

PI: Frei U.

Funding: R.F. Baker Center for Plant Breeding