Wei Wang: CRISPR-Cas9 Genome Editing Technology as a Tool for Precision Breeding in Wheat
Wheat is one of the major sources of calories and protein in human diet. Compared to rice, the genetic analyses of yield-related traits in wheat lagged behind. Release of the wheat genome reference facilitated identification of the wheat orthologs of genes from other crops that contribute to the yield potential. The CRISPR-Cas9-based gene editing technology has revolutionized the basic and applied research in many fields including medicine and agriculture, and provided a powerful tool for functional analyses of yield component genes identified by comparative genomics in our study. Our group built a CRISPR-Cas9-based wheat gene editing platform that combines high-throughput screening of gene editing reagents in the wheat protoplasts, Next-Generation-Sequencing of multiplexed amplicons from the edited genomic regions, and bioinformatical pipeline for the automated detection of editing events in the genome. We have screened more than 350 CRISPR-Cas9 targets for more than 20 selected genes. Gene edited plants were regenerated, screened and phenotyped.
In my talk, I will briefly introduce the CRISPR-Cas9 target screening platform. And then I will focus on the studies of the TaGW2 and TaGW7 genes. We showed that the loss-function mutations in both genes increase the grain weight. The loss-function variant of TaGW2 increased both grain width and length while loss-function variant of TaGW7 increased grain width but decreased grain length. For both genes, the phenotypic effects of mutations in the homoeologs from the A, B and D genome were additive, and the phenotypic effect of each homoeolog was consistent with their expression level. The phenotypic effects of the TaGW2 homoeologs showed inter-cultivar differences that were consistent with the contribution of respective homoeologous gene copies to the total gene expression level of TaGW2. The co-expression network and domestication history of TaGW7 gene was studied. It was found that the that TaGW7 gene was involved in the pathways regulating cell division and organ growth, which was confirmed by the cellular colocalization of TaGW7 with α- and β- tubulin proteins, the building blocks of microtubule arrays. The analyses of exome capture data in tetraploid domesticated and wild emmer, and hexaploid wheat revealed the loss of diversity around TaGW7 associated with domestication selection, suggesting that TaGW7 likely played important role in the evolution of yield component traits in wheat.
Our study shows how integrating CRISPR-Cas9 gene editing with cross-species comparison can help to uncover the function of a gene in wheat and select targets for engineering new gene variants for crop improvement. View Abstract (PDF).
Thursday, October 10, 2019 at 3:45pm