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The C1-I haploid inducer is a maternal haploid inducer line, fixed for the allele C1-I. C1 is a transcription factor in the anthocyanin pathway. The allele C1-I suppresses the formation of anthocyanin even in the presence of R1-nj, a visual selectable marker commonly used in haploid selection. Thus C1-I haploid inducer allows to induce and visually select haploid seed in inducer backgrounds. The C1-I haploid inducer facilitate the application of Doubled Haploid (DH) technology in haploid inducer development.

During the maintenance of haploid inducing germplasm, a certain percentage of "self-induced" offspring can be observed, showing that haploids in the genetic background of haploid inducer lines are possible, and that they are able to germinate and grow into haploid plants. Thus DH technology  could be applied in inducer development, provided a system for haploid detection is available. We exploited the interaction between the two transcription factors R1 and C1, that regulate the anthocyanin pathway: the C1-I allele effectively suppresses anthocyanin production in the seed in the presence of R1-nj.

The development of haploid inducing lines requires testing of induction rates over several generations until the lines are sufficiently inbred so that a stable induction ability is reached. Using DH technology in inducer development can reduce the time and costs of screening for haploid induction ability considerably.

Germplasm with haploid inducing ability and the selectable marker R1-nj fixed serve as donor/female in the induction crosses with the C1-I inducer. The majority of the induced seeds are hybrids between the donor and the C1-I haploid inudcer and will therefore not show the typical anthocyanin coloring in the aleurone and the embryo of the seed. Haploid inducer backgrounds that have the red root marker (Pl1) in addition to the selectable marker R1-nj will show some coloring toward the base of the kernel, but not in the embryo itself. Haploid seed will show an uncolored aleuron and a colored embryo (for illustration: https://www.doubledhaploid.biotech.iastate.edu/c1-i-haploid-inducer ).

The C1-I haploid inducer was developed based on ISURF# 04099, and is able to overcome the Ga1 allele in inducer backgrounds.

This technology is related to ISURF #4065: Midwest Adapted Haploid Inducer for Maize and ISURF 4099: Haploid Inducing Genotype for Specialty Corn

• C1-I inducer allows the application of DH technology and its advantages to haploid inducer development

• Reduces time and costs in haploid inducer development

The C1-I haploid inducer allows the generation and selection of haploids in maternal haploid inducer backgrounds.

Tangible Material