AUTHOR=Oz Mehmet Tufan , Altpeter Angelika , Karan Ratna , Merotto Aldo , Altpeter Fredy 

TITLE=CRISPR/Cas9-Mediated Multi-Allelic Gene Targeting in Sugarcane Confers Herbicide Tolerance

JOURNAL=Frontiers in Genome Editing

VOLUME=3

YEAR=2021

URL=https://www.frontiersin.org/journals/genome-editing/articles/10.3389/fgeed.2021.673566

DOI=10.3389/fgeed.2021.673566

ISSN=2673-3439

ABSTRACT=<p>Sugarcane is the source of 80% of the sugar and 26% of the bioethanol produced globally. However, its complex, highly polyploid genome (2<italic>n</italic> = 100 – 120) impedes crop improvement. Here, we report efficient and reproducible gene targeting (GT) in sugarcane, enabling precise co-editing of multiple alleles <italic>via</italic> template-mediated and homology-directed repair (HDR) of DNA double strand breaks induced by the programmable nuclease CRISPR/Cas9. The evaluation of 146 independently transformed plants from five independent experiments revealed a targeted nucleotide replacement that resulted in both targeted amino acid substitutions W574L and S653I in the acetolactate synthase (ALS) in 11 lines in addition to single, targeted amino acid substitutions W574L or S653I in 25 or 18 lines, respectively. Co-editing of up to three ALS copies/alleles that confer herbicide tolerance was confirmed by Sanger sequencing of cloned long polymerase chain reaction (PCR) amplicons. This work will enable crop improvement by conversion of inferior alleles to superior alleles through targeted nucleotide substitutions.</p>