CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS
XU Yunbi,YANG QuanNü,ZHENG HongJian,XU YanFen,SANG ZhiQin,GUO ZiFeng,PENG Hai,ZHANG Cong,LAN HaoFa,WANG YunBo,WU KunSheng,TAO JiaJun,ZHANG JiaNan
Genotyping technology, via molecular markers, has been playing a key role in many biological fields including genetic improvement. Genotyping has been widely applied in multi-national seed companies due to their high-throughput, automatic, large-scale and shared genotyping platforms. Genotyping has moved from its third generation (G3), dominated by expensive DNA chips and random genotyping by sequencing (GBS), to the fourth generation (G4), characterized by low-cost, less facility-demanding and performed via genotyping by target sequencing (GBTS). In this article, we first introduced two GBTS protocols, GenoPlexs, based on multiplexing PCR, and GenoBaits, based on sequence capture in-solution (also called liquid chip). For both protocols, multiple single-nucleotide-polymorphisms (mSNP) or multiple dispersed nucleotide polymorphisms (MNP) can be generated to reveal the genetic variation hidden within each amplified locus (amplicon). Compared to DNA chips and GBS, GBTS has several advantages, including wide applicability to genotyping facilities, very flexible marker types, highly efficient genotyping, sharable and accumulative marker data, less required information management and support, and wide suitability in biological applications. With the same marker panel (for example, 40K maize mSNPs), three types of genotyping (40K mSNPs, 260K SNPs, and 754K haplotypes) can be achieved, and multiple panels with various marker densities (1K to 40K mSNPs) can be generated by sequencing at different depths. Applications of GenoPlexs and GenoBaits in biology were then reviewed, including biological evolution, germplasm evaluation, genetic map construction, gene mapping and cloning, marker-trait association (genome-wide association study and bulked sample analysis, BSA), progeny testing, gene introgression, gene pyramiding, variety right protection, variety quality monitoring, transgenic event and gene editing detection, and bioassay. More 50 marker panels have been developed so far for more than 20 plant, animal and microorganism species and applied in some of the fields described above. Lastly, we prospected for future GBTS by looking insights into carry-on, automatic, high-throughput and intelligent genotyping platforms, multi-functional marker panels with various marker densities designed to meet specific requirements, integration with other technologies such as KASP, high-density DNA chips and BSA strategies, and open-source breeding by sharing germplasm and breeding materials and information. The development in these fields will greatly facilitate the applications of GBTS in genetic improvement and other fields of animals, plants and microorganisms.