Multiparental populations in line development: Genetic gain, diversity, and practical limitations

New homozygous lines are usually developed from biparental crosses. To my knowledge, biparental and multiparental crosses have not been directly compared as breeding populations. My objective in this simulation study was to determine whether a set of several biparental populations or a single multiparental population is superior in terms of genetic gain and diversity of the best ensuing lines. Multiparental populations were simulated from p = 4, 6, and 8 parents and were compared with the corresponding p(p – 1)/2 biparental populations (i.e., diallel). Each of 250 quantitative trait loci had p alleles. Parental selection was mimicked via a Better Half model, wherein only the better crosses (e.g., four out of six with p = 4) were made. Genetic gains were equal between the Better Half model and the full diallel despite the larger population size with the latter. Current timelines for cultivar development in different species impose a limit on the number of generations available for creating multiparental populations, and the results indicated only a minimal (if any) increase in genetic gain when lines were developed from multiparental populations instead of biparental populations. The main benefit from multiparental populations was a better retention of genetic diversity among the selected lines. It remains to be seen whether this higher diversity among new lines from multiparental populations would lead to larger or more-sustained gains in future lines.