文章基本信息

标题：Strategies to produce T-DNA free CRISPRed fruit trees via Agrobacterium tumefaciens stable gene transfer
其他标题：Strategies to produce T-DNA free CRISPRed fruit trees via Agrobacterium tumefaciens stable gene transfer
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作者：Lorenza Dalla Costa ; Stefano Piazza ; Valerio Pompili 等
期刊名称：Scientific Reports
电子版ISSN：2045-2322
出版年度：2020
卷号：10
期号：1
页码：1-14
DOI：10.1038/s41598-020-77110-1
出版社：Springer Nature
摘要：Genome editing via CRISPR/Cas9 is a powerful technology, which has been widely applied to improve traits in cereals, vegetables and even fruit trees. For the delivery of CRISPR/Cas9 components into dicotyledonous plants, Agrobacterium tumefaciens mediated gene transfer is still the prevalent method, although editing is often accompanied by the integration of the bacterial T-DNA into the host genome. We assessed two approaches in order to achieve T-DNA excision from the plant genome, minimizing the extent of foreign DNA left behind. The first is based on the Flp/FRT system and the second on Cas9 and synthetic cleavage target sites (CTS) close to T-DNA borders, which are recognized by the sgRNA. Several grapevine and apple lines, transformed with a panel of CRISPR/SpCas9 binary vectors, were regenerated and characterized for T-DNA copy number and for the rate of targeted editing. As detected by an optimized NGS-based sequencing method, trimming at T-DNA borders occurred in 100% of the lines, impairing in most cases the excision. Another observation was the leakage activity of Cas9 which produced pierced and therefore non-functional CTS. Deletions of genomic DNA and presence of filler DNA were also noticed at the junctions between T-DNA and genomic DNA. This study proved that many factors must be considered for designing efficient binary vectors capable of minimizing the presence of exogenous DNA in CRISPRed fruit trees.