Genetic gain is one of the important concepts in quantitative genetics and breeding,which can be defined as the increase in productivity achieved following a change in gene frequency affected by selection.To develop breeding products to meet the increasing demand of agricultural products,breeders are challenged to improve realized genetic gain continuously.The factors affecting genetic gain include genetic variation in breeding populations,heritability of target traits,selection intensity,and breeding cycle time.The strategies for improvement of genetic gain have been evolving with modem breeding techniques and platforms,mainly driven by genomics and related tools.Favorable genetic variation can be mined through unlocking germplasm resources.