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

Mehmet Tufan Oz; Angelika Altpeter; Ratna Karan; Aldo Merotto; Fredy Altpeter

doi:10.3389/fgeed.2021.673566

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

Front Genome Ed. 2021 Jul 8:3:673566. doi: 10.3389/fgeed.2021.673566. eCollection 2021.

Authors

Mehmet Tufan Oz^{1

2}, Angelika Altpeter¹, Ratna Karan¹, Aldo Merotto¹, Fredy Altpeter^{1

2}

Affiliations

¹ Agronomy Department, Plant Molecular and Cellular Biology Program, Genetics Institute, University of Florida, IFAS, Gainesville, FL, United States.
² DOE Center for Advanced Bioenergy and Bioproducts Innovation, Gainesville, FL, United States.

Abstract

Sugarcane is the source of 80% of the sugar and 26% of the bioethanol produced globally. However, its complex, highly polyploid genome (2n = 100 - 120) impedes crop improvement. Here, we report efficient and reproducible gene targeting (GT) in sugarcane, enabling precise co-editing of multiple alleles via 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.

Keywords: CRISPR/Cas9; gene targeting; genome editing; homologous recombination; homology directed repair; sugarcane (Saccharum hybrid complex).