TABLE 3.

Summary of genome editing studies for toxic metals/metalloids tolerance in different plant species.

Metals/metalloids	Plant species	Gene target	Modification	Key observations	References
Iron	Arabidopsis thaliana	GSNOR	Knock-out	Mutants were found to be sensitive to high Fe toxicity, showing this gene to generate tolerance in roots against Fe stress.	Li et al., 2019
Cadmium	Oryza sativa	OsABCG36	Knock-out	Targeted gene could transport Cd out of the cell to detoxify its effect. Mutants were tolerant to Cd accumulation in roots, but not in shoots.	Fu et al., 2019
Cadmium	Arabidopsis thaliana	AtPDF2.6	Knock-out	Loss of AtPDF2.6 gene reduced tolerance against Cd and was significantly accumulated when exposed to Cd stress. Mainly expressed in root tissues.	Luo et al., 2019
Cadmium and manganese	Oryza sativa	OsNRAMP1	Knock-out	Reduced uptake and transportation of Mg, Fe, Cd, and As.	Chang et al., 2020
Cadmium	Solanum lycopersicum	class II glutaredoxin	Knock-out	Knockout mutation on members of class II glutaredoxin (GRXs) against Cd toxicity protected chloroplasts of cells.	Kakeshpour, 2020
Zinc and copper	Oryza sativa	OsZIP9	Knock-out	Higher concentration of Zn improved the growth of plants.	Yang M. et al., 2020
Iron and zinc	Oryza sativa	OsIRO3	Knock-out	Accumulation of ROS. Maintenance of Fe homeostasis by tolerating Fe deficiency or toxicity.	Wang et al., 2020c
Zinc	Arabidopsis thaliana	OZS3	Knock-out	Complete loss of the OZS3 gene resulted in reduced growth, early flowering and long petioles.	Weber et al., 2020