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Improving Haploid Inducing Lines

Haploid Inducing Lines for Licensing

Development of a high oil haploid inducer line

Generating Inducer DH-Lines

Genome wide association studies and prediction in inducer populations

Applying genomic selection in haploid inducer development


A common ancestor of all haploid inducing lines in maize is Stock 6, developed and published by Ed Coe in 1959. While Stock 6 showed an induction rate if 2-3%, continuous breeding and selection resulted in steadily increasing induction rates and improved agronomic performance of haploid inducing lines. Mapping studies identified genome regions, that contribute to the trait. Two major quantitative trait loci (QTLs) were described qhir1 and qhir8, explaining 60% and 20% respectively of the genotypic variance (Prigge2012, Dong et al. 2013). This knowledge allowed marker assisted introgression of haploid induction ability in various genetic backgrounds. In 2017 the gene behind the qhir1 was identified  - ZmMTL (Kelliher et al., 2017; Gilles et al., 2017; Liu et al., 2017). The gene responsible for the enhanced induction rates in the presence of ZmMTL, was published in 2019 by Zhong et al. and named ZmDMP.

At the DH Facility our inducer development in the beginning was focused on the development of germplasm with good adaptation to the growing conditions in the Mid West, increased induction rates, additional selectable marker and the ability to overcome crossing barriers like gametophytic factor 1 (Ga1). Haploid Inducing Lines for Licensing

As the visual selection of haploids is a labor- and time-intensive task, selectable traits that allow machine sorting of haploid versus diploid/hybrid kernels come into focus. Also, specialty corn and sweetcorn inductions often do not allow visual selection based on R1-nj expression or even the coloring of the root, due to the presence of factors suppressing anthocyanin expression or already high coloring of the donor line itself. For NIRS based sorting applications especially the oil content is of interest, as the majority of the oil content of a maize seed is concentrated in the embryo. Development of a high oil haploid inducer line

To increase our efficiency to respond to changing demands on traits necessary in haploid inducing lines to enable machine selection or adaptation to changing environments, we are using DH technology to generate inducer DH lines, A specially developed  inducer allows induction and selection of haploid kernels in colored inducer backgrounds based on the C1-I allele. Generating Inducer DH-Lines

Haploid Induction ability is a highly quantitative trait. Other factors besides the two major genes ZmMTL and ZmDMP contribute to the performance of a haploid inducing line. Genome wide association studies allow to identifying other genomic regions contributing as well as give  us the ability to predict the performance of specific inducer combinations. Genome wide association studies and prediction in inducer populations

Based on high throughput genotyping, the breeding process of new inducer lines can be further optimized by establishing genomic selection. Applying genomic selection in haploid inducer development