Rapid Cycling Genomic Selection in a Multiparental Tropical Maize Population

Area of Science:

• Plant breeding
• Genetics
• Agricultural science

Background:

• Genomic selection (GS) accelerates genetic gain by shortening breeding cycles, previously shown in biparental maize populations.
• Application of GS in multi-parental tropical maize populations remained unexplored.

Purpose of the Study:

• To evaluate the realized genetic gains of rapid cycling genomic selection (RCGS) in a tropical maize multi-parental population.
• To assess the impact of RCGS on genetic diversity over four recombination cycles.

Main Methods:

• Developed a training population from 18 elite tropical maize lines intercrossed twice and self-pollinated once (Cycle 0).
• Genotyped 1000 families using 955,690 SNP markers and phenotyped testcrosses across four locations.
• Implemented RCGS by selecting elite individuals for intermating across four cycles, achieving two cycles per year.
• Evaluated multi-environment trials of all cycles against benchmark checks.

Main Results:

• Achieved a realized grain yield gain of 0.225 ton ha⁻¹ per cycle from Cycle 1 to Cycle 4.
• This translates to a genetic gain of 0.100 ton ha⁻¹ yr⁻¹ over a 4.5-year breeding period.
• Observed only a slight reduction in genetic diversity in later GS cycles (Cycle 3 and Cycle 4).

Conclusions:

• RCGS is an effective breeding strategy for tropical maize multi-parental populations.
• RCGS simultaneously achieves high genetic gains and conserves genetic diversity within a short timeframe.