摘要
CRISPR/Cas enables robust genome editing and has revolution-ized both functional genomics and crop breeding.The specificity of Cas-directed DNA cleavage is strictly determined by a chimeric single guide RNA(SgRNA)and a short protospacer adjacent motif(PAM)in the genome(Cong et al,2013;Zetsche et al,2015).The widely used Cas9 from Streptococcus pyogenes(SpCas9)generally recognizes the canonical NGG PAM(where N indicates any nucleicacid base)(Miao et al.,2013;Ma et al,2015),making many regionsuntargetable by Cas9.SpCas9 VQR and VRER variants,which recog-nize the non-canonical PAM sequences of NGA and NGCG,respectively,have been used to expand targetable sequences in plants(Hu et al.,2016).In addition,the applications of other Cas endonucleases such as SaCas9(Staphylococcus aureus Cas9)(Ran et al..2015).
基金
partly funded by the Ministry of Agriculture and Rural Affairs of China(2016ZX08010003 to L.Q.X.)
the Central Non-Profit Fundamental Research Funding supported by Institute of Crop Sciences,Chinese Academy of Agricultural Sciences(S2018QY05 to L.Q.X.)
