An introgression strategy to expand genetic variation

Introgression has been used to generate novel allotetraploid Brassica germplasm, improving the yield of Brassica napus and expanding the genetic base of Brassica carinata. The identification of introgressed segments in hybrids is critical in molecular breeding. The widespread use of molecular markers has provided breeders with a powerful tool to precisely select the desired genotype. Genetic introgression can also be assayed using molecular markers. Single nucleotide polymorphisms (SNPs), as a third-generation marker system with high polymorphism and high density across the genome, have been used for crops such as B. rapa and B. napus. Kompetitive allele-specific PCR (KASP) is currently the most popular SNP genotyping technology. It has high throughput and accuracy, and it can be used in marker-assisted selection (MAS). However, KASP markers suitable for assisting large-scale interspecific introgression in Brassicaceae species have not previously been developed. In addition, the genetics of the fragments introgressed from one contributor diploid species to the allotetraploid species is largely unknown.

Recently, scientists from the Chinese Academy of Agricultural Science created a set of novel germplasm by introgressing the diploid B. rapa genome into B. juncea and then systematically evaluated the expanded diversity at the whole-genome level. They demonstrated that the genetic distance of heading B. juncea was greatly enhanced from 0.03 to an estimated maximum of 0.33 using a set of genome-wide SNPs. Increased phenotypic variation was also observed among the introgression lines, corresponding to the increased genetic diversity.

“To our knowledge, no other report has adopted the strategy of introducing genetic variations from their diploid contributor species”, Prof Wang said. These results provide us with a new method to expand the genetic variation of Brassica species, and this introgression strategy can also be extended to improving other allotetraploid Brassica species.

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Reference

Authors

Li Zhang, Xiangsheng Li, Lichun Chang, Tianpeng Wang, Jianli Liang, Runmao Lin, Jian Wu, Xiaowu Wang

Affiliations

Institute of Vegetables and Flowers, Chinese Academy of Agricultural Science, 100081 Beijing, China

About Xiaowu Wang

Prof. Xiaowu Wang is mainly engaged in genomics, molecular genetics, and molecular breeding of cruciferous vegetable crops. Prof. Wang is committed to using genomics tools to analyze the formation, evolution, and domestication of key traits such as leaf bulbs, swollen roots, and the bolting and flowering of Brassica vegetables. Prof. Wang completed the first genome sequence of Chinese cabbage and participated in the genome sequencing of cabbage, rapeseed, and mustard. Prof. Wang has published more than 120 papers in international journals such as Nature Genetics, Nature Communications, Plant Cell, Proceedings of the National Academy of Sciences of the United States of America, and others.