Genomewide Selection to Introgress Semidwarf Maize Germplasm into U.S. Corn Belt Inbreds

Abstract

Semidwarf maize (Zea mays L.) could be grown in new areas of production or in alternative crop rotations. Our objectives were to determine (i) if genomewide selection is useful for the rapid improvement of an exotic × adapted cross, (ii) if genomewide selection is more effective than phenotypic backcrossing for a trait with major genes, and (iii) the extent to which the high grain yield of nondwarf maize can be combined with the reduced stature and adaptability to high plant population densities of semidwarf maize. We conducted four cycles of genomewide selection in two semidwarf × adapted crosses. Phenotypic backcrossing was also done until the BC4 with selection for short plants. The accuracy of genomewide predictions in Cycle 0 was 0.67 to 0.70 for plant height and 0.57 to 0.70 for grain yield. Genomewide selection from Cycle 1 until Cycle 5 either maintained or improved on the gains from phenotypic selection achieved in Cycle 1. Observed gains generally agreed with predicted gains. Cycle 5 did not always have the best mean performance. Unfavorable genetic correlations made it difficult to select for short plants with high grain yield. Linkage disequilibrium between markers declined as selection progressed. Compared with phenotypic backcrossing, genomewide selection led to better mean performance and a higher proportion of exotic germplasm introgressed. To our knowledge, this is the first empirical study on genomewide selection to improve an exotic × adapted cross.

Genomic assisted selection for enhancing line breeding: merging genomic and phenotypic selection in winter wheat breeding programs with preliminary yield trials

“…The implementation of classical marker assisted selection was, however, of limited success for quantitatively inherited traits that are controlled by many loci, while with the advent of genomic selection handling these complex genetic architectures became a much more feasible task in recent years (Jannink et al 2010; Crossa et al 2014; Heslot et al 2015). Although genomic selection has been found to be superior to conventional phenotypic selection and gave outstanding results in several selection experiments (Combs and Bernardo 2013; Beyene et al 2015; Rutkoski et al 2015b), genomic predictions rely strongly on genetic relationships and not on physical measurements on the selection candidates.…”

General Combining Ability Model for Genomewide Selection in a Biparental Cross

“…Time and cost are particularly limiting in inbred development that does not involve recurrent selection; in the latter, the time and cost in phenotyping can be justified by the increase in the gain per unit time when multiple cycles of genomewide selection are performed in a year-round nursery or greenhouse (Massman et al, 2012;Combs and Bernardo, 2013a). But PS and the A/B model are highly time consuming and expensive because the A/B population itself needs to be phenotyped.…”

Parâmetros genéticos e associação de metodologias de EUN no milho sob diferentes doses de nitrogênio

“…A seleção de genótipos superiores em condições de baixo fornecimento de N é uma alternativa que se relaciona ao contexto global pela busca de genótipos eficientes 4,6 com melhor utilização do N 21 com alta tolerância a estresses …”

“…3 O nitrogênio, de acordo com Cirilo et al, 4 é um dos fatores que limitam a produção vegetal em virtude da sua essencialidade para as plantas 2 e pelos impactos gerados pelo manejo inadequado dos fertilizantes. 5 Na maioria dos solos, a disponibilidade de N é limitada (baixa), no entanto, é possível encontrar genótipos de milho produtivos nestas condições 6 . Por exemplo, Chen et al 5 reportam que genótipos desenvolvidos em ambientes com baixa disponibilidade de N podem resultar em ganhos de 10% a 14% na produtividade de grãos.…”