Doubled Haploid Technology for Rapid and Efficient Maize Breeding

Abstract

Doubled haploid (DH) technology is becoming an integral part of maize breeding programs worldwide due to the various advantages it offers, including its quick and efficient development of completely homozygous inbred lines. Use of DH lines compared to use of conventional inbred lines developed through recurrent self-pollinations enables maize breeding programs to reduce the time and cost of product development, besides simplified logistics and increased selection efficiency. In combination with molecular marker technologies, DH can greatly accelerate genetic gains. However, adoption of DH technology in maize breeding programs depends on reliable and cost-efficient production of DH lines at scale. DH technology has significantly evolved over the last five to six decades. Various methods have been reported for haploid induction, identification of putative haploids, and chromosome doubling. Recent advances in the DH process have increased the reliability and efficiency of DH line production in maize germplasm. Development of new haploid inducers with high haploid induction rates (HIRs) and adapted to different target environments has facilitated increased adoption of DH technology in new environments. Haploid identification is being optimized using different genetic markers, and nongenetic methods (including automation), thereby reducing the cost and time expended in haploid identification. Achieving high rates of chromosomal doubling and use of less-toxic chemicals are other important areas for continuous process improvement. In this chapter, the various steps involved in maize DH line production, the technological improvements that have happened at each step, and the advantages of using DH lines in maize breeding are discussed.