Doubled Haploid Technology: Opportunities and Challenges for the Rapid Generation of Maize Homozygous Lines.

Maize is used for multiple purposes, including food, feed, and energy production, and since transitioning to hybrid cultivars at around 1930, maize yield has significantly increased. This is largely due to hybrid vigor, which refers to the superior performance of the progeny from two unrelated inbred parents. Consequently, nearly all maize cultivars grown in the United States are hybrids. Hybrid breeding programs comprise two essential components; namely, inbred line development and hybrid production. Traditionally, developing inbred lines takes a long time, requiring six to 10 generations of self-pollination. The doubled haploid (DH) technology, however, accelerates this process, enabling the derivation of fully homozygous lines within two generations. DH technology is applicable in several crop species and has been most successful in maize due to in vivo maternal haploid induction. Here, we review the origins of the DH technology, and discuss advantages and challenges of the technology as well as applications of DH lines.