Haploid System in Mutation Breeding

During a century since the discovery of the first haploid in Datura stramonium in 1923, doubled haploids (DH) have played a critical role in simplifying plant breeding approaches and development of new cultivars (rice, wheat, etc.) or parents of hybrids (maize, rapeseed, etc.). Mutation breeding, which started in 1920 by radiation of plants to induce genetic variations, has evolved from random mutations using physical and later chemical mutagens to safer random and precise mutagenesis using biological approaches. Both mutation breeding and DH technology enable breeders to create new genetic/phenotypic variations and facilitate the detection/application of beneficial ones, respectively. In mutation breeding programs, haploids and DHs are produced in vitro by androgenesis, gynogenesis or in vivo by uniparental genome elimination. In vitro and in vivo DH production facilitate mutation breeding by fast fixation of recessive mutations and obtaining homozygous lines. The gametes of mutated seeds, directly mutated gametes, or in vitro selected mutants can be used for DH production. Also, DH technology decreases the timing and the cost needed to evaluate gene-trait relations in the mutated populations and site-directed mutagenesis. This chapter focuses on the different aspects of DH technology application in mutation breeding and considers new approaches and technologies in both areas.