Should maize doubled haploids be induced among F or F plants

摘要

Maize (Zea mays L.) doubled haploid lines are typically produced from F plants. Studies have suggested that the low frequency of recombinants in doubled haploids may reduce the response to selection. My objective was to determine if, for sustaining long-term response, doubled haploids should be induced in F or F plants during maize inbred development. In simulation experiments, I examined the response to multiple cycles of testcross selection among doubled haploid lines derived from F plants (denoted by DH), doubled haploid lines derived from F plants (DHF), and recombinant inbred (RI) lines derived by single-seed descent. For a trait controlled by 100 or more quantitative trait loci (QTL), the cumulative responses to selection were up to 4-6% larger among DHF lines than among DH lines. The cumulative responses were up to 5-8% larger among RI lines than among DH lines. The QTL become unlinked as the number of QTL in a finite genome decreases, and the responses among RI, DH, and DHF lines were equal or nearly equal when only 20 QTL controlled the trait. Metabolic-flux epistasis reduced the differences in the response among RI, DH, and DHF lines. Overall, the results indicated that doubled haploids should be induced from F plants rather than from F plants. If year-round nurseries are used and new F crosses for inbred development are initially created on a speculative basis, the development of doubled haploids from F rather than F plants should not cause a delay in inbred development.