Generation of Maize (Zea mays) Doubled Haploids via Traditional Methods

Abstract

Commercial maize hybrid production has corroborated the usefulness of producing inbred lines; however, the delivery of new lines has always been a major time constraint in breeding programs. Traditional methods for developing inbred lines typically require 6 to 10 generations of self-pollination to obtain sufficient homozygosity. To bypass the time and costs associated with the development of inbred lines, doubled haploid (DH) systems have been widely adopted in the commercial production of maize. Within just two generations, DH systems can create completely homozygous and homogeneous lines. A typical maize DH system, utilizing anthocyanin markers R1-nj or Pl1 for haploid selection, is described in this protocol. ABSTRACTCommercial maize hybrid production has corroborated the usefulness of producing inbred lines, however, the delivery of new lines has always been a major time constraint in breeding programs. Traditional methods for developing inbred lines typically require 6-10 generations of self-pollination to obtain sufficient homozygosity. To bypass the time and costs associated with the development of inbred lines, doubled haploid (DH) systems have been widely adopted in the commercial production of maize. Within just two generations, DH systems can create completely homozygous and homogeneous lines. A typical maize DH system, utilizing anthocyanin markers R1-nj or Pl1 for haploid selection, is described in this protocol.

The development of homozygous maize lines using an in vivo haploid induction in the Croatian germplasm

“…In the greenhouse, 42.4% of the haploid plants produced fertile pollen and 30.5% of them could be selfed, whereas 16.1% of the haploid plants in the field were the male fertile ones, 11.3% of them could be self-pollinated, and 8.1% produced seeds after selfing. Vanous et al (2017) quoted that the doubling rates usually range between 20-25%. Self-pollination in the D0 generation was the most successful in the population of Os 2703, in which 69.2% of fertile plants produced seed ( Table 3).…”

“…seeds that resulted in a DH line (Table 4). Vanous et al (2017) noted that the success rates usually range from 8 to 10%. Taking into account that a large number of putative haploids were lost due to the low emergence rates, we also calculated the deriving rates based on a total number of D0 haploids, resulting in 2.2-15.0% of DH lines per population (Table 4).…”

Genetic variation of seedling traits responded to brassinosteroid and gibberellin inhibitors in maize (Zea mays) doubled haploid lines

“…BC 3 F 1 plants were crossed with the inducer hybrid RWS‐9 × RWK‐76 to produce haploid seeds, which were identified using the R‐nj colour marker (Liu et al., 2016; Roeber, Gordillo, & Geiger, 2005). During summer 2016, putative haploids were planted in the greenhouse and treated with colchicine at the 3–4 leaf developmental stage, following the procedure described by Vanous, Vanous, Frei and Lübberstedt (2017). Treated haploid plants were transplanted to the field (Agronomy Farm, Iowa State University, Ames, IA) and self‐pollinated to produce DH lines.…”

A data transfer method for improving seed identification of maize (Zea mays) haploid breeding based on genetic similarity

“…The maize haploid breeding technology is gaining popularity as an attractive breeding technology (Chen, Li, & Li, ; Geiger, ; Geiger & Gordillo, ; Geiger, Gordillo, & Koch, ; Liu, Wang, Ren, Mei, & Ortiz, ; Röber, Gordillo, & Geoger, ; Vanous, Vanous, Frei, & Lübberstedt, ). In 2018, it was listed as one of the top 10 new technologies by China agricultural and rural science and technology summit forum.…”