Abstract: Molecular design breeding is a highly integrated system built on multiple scientific disciplines and technological areas. It allows the simulation and optimization of the breeding procedure before breeders’ field experiments. Thus the best target genotypes to meet various breeding objectives in various ecological regions, and the most efficient and effective crossing and selection strategies approaching the best target genotypes can be identified. The design breeding greatly increases the predictability in conventional breeding, leading to the evolution from “phenotypic breeding by experience” to “genotypic breeding by prediction” and an increased breeding efficiency and effectiveness. Three major steps are involved in design breeding. The first step is to identify genes affecting breeding traits and to study gene and gene interactions, i.e., to seek for the original materials for producing the crop cultivars, which includes establishment of genetic populations, screening of polymorphism markers, construction of linkage maps, phenotypic evaluation and genetic analysis etc. The second step is to determine the target genotypes for various breeding objectives in various ecological regions, i.e., prototype of the final cultivar product, which includes the genotype-to-phenotype prediction based on identified and known gene information, i.e., locations of genes on chromosomes, biochemical pathways and expression networks from genes to traits, their genetic effects on breeding traits, and the interactions between genes. The third step is to identify the most efficient breeding strategies leading to the target genotypes determined in the second step, i.e., a detailed blue chart to produce the designed crop cultivars. Significant progresses have been made in crop molecular design breeding in China in recent years. This paper first summarized major progresses made in the development of novel genetic materials, genetic study of important breeding traits, development and application of breeding simulation tools, application of design breeding, and the platform research and development in molecular design breeding in crops in China. A perspective view of molecular design breeding was given for the near future after reviewing the current research both in China and worldwide. Finally, major research areas relevant to molecular design breeding in China were proposed, among which are prediction methods and tools of genetics and breeding, genetic mating designs and analysis, gene and environment interactions, functional genomics of crops, methods and tools of bioinformatics, technical systems and decision-supported tools. Professional development and education, and team building are essential as well to China’s leading role in crop molecular design breeding in the world.

Key words: Crop, Molecular design breeding, Breeding simulation, Target genotype, Breeding strategy