New Insights into the Genetics of Haploid Male Fertility in Maize

Abstract

Doubled haploid (DH) lines have become widely used in maize (Zea mays L.) breeding. Haploid genome doubling is an important step in developing DH lines. The low rate of spontaneous genome doubling, which causes low haploid male fertility (HMF), seriously limits the largescale application of DH breeding without colchicine treatment. Our objective was to gain new insights into the genetics controlling HMF to improve the rate of HMF in DH breeding procedures. Haploid populations of 20 inbreds and their 31 single crosses derived from Chinese elite maize germplasm were screened for four traits related to HMF: anther emergence rate, pollen production rate, anther emergence score, and pollen production score. Haploid male fertility was compared between single crosses and their parents. Genotype effects were significant (p < 0.01) for all traits among Chinese elite maize lines and their single crosses, and interactions between genotype and environment were also significant (p < 0.05) for anther performance. Heritabilities ranged from 0.68 to 0.91 for these four traits. Haploid male fertility was controlled by additive effects with two or more genes. Anther emergence score proved to be the best trait for describing HMF and is the most practical trait for breeders. We propose that the potential use of HMF in breeding programs could reduce the need for toxic and costly artificial doubling treatments.

Early diagnosis of ploidy status in doubled haploid production of maize by stomata length and flow cytometry measurements

“…Various authors have hypothesized that D 0 plants with seed set are chimeras because usually only sectors of the tassel contain pollen‐shedding anthers (Chang & Coe, ; Chase, ). These observations are in agreement with pollen score data from untreated D 0 plants (Molenaar, Schipprack, Brauner, & Melchinger, ; Wu et al, ). Flow cytometry analyses carried out by Choe et al () as well as in Exp.…”

Novel technologies in doubled haploid line development

“…Wu et al . () reported that haploid male fertility ranges from 9.8 to 89.8%. The maize inbred line ‘Yu87‐1’ showed the highest male fertility.…”

“…Kleiber et al (2012) reported that the range of haploid fertility is 0%-20% in tropical and temperate maize germplasm. Wu et al (2016) reported that haploid male fertility ranges from 9.8 to 89.8%. The maize inbred line 'Yu87-1' showed the highest male fertility.…”

QTL mapping for haploid male fertility by a segregation distortion method and fine mapping of a key QTL qhmf4 in maize

“…Genomes in both haploid male and female cell lines have to be doubled for successful gamete formation and subsequent DH line production. Female fertility is generally high in haploids without artificial treatment (Chase 1952;Chalyk 1994;Geiger et al 2006;Wu et al 2017). It is reported that more than 90% of haploid ears produce seed after pollination with normal pollen from diploid plants (Chalyk et al 1994).…”