CRISPR/Cas9-Mediated Targeted Mutagenesis of Wild Soybean (Glycine soja) Hairy Roots Altered the Transcription Profile of the Mutant

Clustered Regularly Interspaced Short Palindromic Repeat/CRISPR-associated protein 9 (CRISPR/Cas9) system has been regularly applied for genome editing and gene function identification in wild soybean (Glycine max) cultivars. However, till date no studies have demonstrated successful mutagenesis in wild soybean (Glycine soja) which is the ancestor of Glycine max and rich in stress tolerance genes. In the current study, we report the successful creation of mutations in the loci encoding plasma membrane Na+/H+ antiporter (SOS1) and nonselective cation channels (NSCC) in wild soybean hairy roots using the CRISPR/Cas9 system. Two genes, GsSOS1 and GsNSCC, were mutagenized with frequencies of 28.5% and 39.9%, respectively. Biallelic mutations in GsSOS1 were detected in transgenic hairy roots. GsSOS1 mutants exhibited altered Na+/K+ ratios in the roots under both control and salt-treated conditions. However, no significant effects of GsNSCC mutation on Na+/K+ ratios were observed. RNA-Seq analysis revealed that both GsSOS1 and GsNSCC mutation altered the transcription profiles in mutant roots. Many differentially expressed gene sets that are associated with various cellular functions were identified. Our results demonstrated that CRISPR/Cas9 systems as powerful tools for wild soybean genome editing and would significantly advance the gene mining and functional identification in wild soybean.