Weeds are important biotic constraints to agricultural production, so
herbicides are widely used with agronomic crops as the primary method of
weed control. Accordingly, extensive efforts to develop
herbicide-resistant (HR) crops have been made using various methods,
including clustered regularly interspaced short palindromic
repeats/CRISPR-associated protein 9 (CRISPR/Cas9)-mediated gene editing.

Thus far, most of the HR crops developed using gene-editing methods have
adopted site-specific mutations of endogenous genes, but rarely by
insertion or deletion (indel) mutations. In this study, we attempted to
confer herbicide resistance in plants via indel mutations using the
CRISPR/Cas9-mediated editing of 5-oxoprolinase 1 (/OXP1/) gene as a
target in/Arabidopsis/.

OXP1 is an enzyme that is involved in 5-oxoproline metabolism and the
glutathione recycling pathway. Here, we generated the indel mutants
of/Arabidopsis/using/OXP1/editing (/oxp1//CRISPR), and verified a
reduced sensitivity to sulfamethoxazole (Smex), a sulfonamide herbicide
that suppresses the growth of cells by inhibiting the folic acid
biosynthetic pathway.

In addition, we successfully obtained/OXP1/-edited plants by screening
the transgenic plants on Smex-containing media, suggesting the possible
use of/OXP1/as a marker for plant gene editing. Subsequent molecular
analyses demonstrated the indel mutations on/OXP1/in the
Smex-resistant/Arabidopsis/plants.

Moreover, the/oxp1//CRISPR plants exhibited tolerance to heavy metals,
such as cadmium, and another sulfonamide compound, amisulbrom.
Therefore, the present study provides a way to confer resistance to
sulfonamide compounds in plants by generating indel mutations.

CRISPR/Cas9-mediated mutation of 5-oxoprolinase gene confers resistance
to sulfonamide compounds in Arabidopsis | SpringerLink
[link.springer.com]