Submitted to: Plant Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/12/2016
Publication Date: 10/5/2016
Citation: Smelser, A., Gardner, C.A., Blanco, M., Lübberstedt, T., Frei, U. 2016. Germplasm enhancement of maize: A look into haploid induction and chromosomal doubling of haploids from temperate-adapted tropical sources. Plant Breeding. 135(5):593-597.

Interpretive Summary: Doubled haploid technology is used to develop completely homozygous inbred lines, where each of the chromatids making up a chromosome pair are identical. Two inbred lines, PHB47 and PHZ51, were used to make backcrosses to 18 maize landraces, generating 36 populations. The landraces were chosen based on the elevation of their origins, whether high, middle or low altitude. These populations were crossed to a haploid induction male parent, and kernels with haploid phenotype were selected. These kernels were planted, the seedlings treated with colchine to effect chromosome doubling, tranplanted to the field, and self-pollinated if they shed pollen and produced silks at the same time. We assessed whether haploid induction rates and subsequent doubling rates are impacted by use of either of two recurrent inbred parents used to make the backcrosses, or by the elevation of the landraces' place of origin. Recurrent parent effect was significant, with PHB47 having a higher haploid induction rate than PHZ51. Elevation was significant, with higher haploid induction rate associated with low elevation origin, and race also proved to be significant. None of these factors had a significant association with doubling rate.

Technical Abstract: Doubled haploid technology is used to develop completely homozygous inbred lines, where each of the chromatids making up a chromosome pair are identical. Two inbred lines, PHB47 and PHZ51, were used to make backcrosses to 18 maize landraces, generating 36 populations. The landraces were chosen based on the elevation of their origins, whether high, middle or low altitude. These populations were crossed to a haploid induction male parent, and kernels with haploid phenotype were selected. These kernels were planted, the seedlings treated with colchine to effect chromosome doubling, tranplanted to the field, and self-pollinated if they shed pollen and produced silks at the same time. We assessed whether haploid induction rates and subsequent doubling rates are impacted by use of either of two recurrent inbred parents used to make the backcrosses, or by the elevation of the landraces' place of origin. Recurrent parent effect was significant, with PHB47 having a higher haploid induction rate than PHZ51. Elevation was significant, with higher haploid induction rate associated with low elevation origin, and race also proved to be significant. None of these factors had a significant association with doubling rate.