Sucrose transporters and calcium oxide mitigate cadmium toxicity in rice by regulating carbohydrate metabolism, metal transporters, and oxidative stress

Sucrose metabolism is pivotal to the energy supply mechanism in plants, significantly influencing signaling and developmental processes. Double gene mutants of sucrose transporters, OsSUT2 and OsSUT4 , in rice were treated with Cd and CaO-NPs. The findings indicated that Cd toxicity significantly impaired rice growth and photosynthetic parameters, resulting in an increase in reactive oxygen species (ROS), which was particularly pronounced in the mutant line. The Cd levels of the mutant rice roots and shoots exhibited a 20.08 % and 30.98 % increase compared to the wild-type. Concurrently, MDA and H 2 O 2 levels increased by 43.78 % and 22.85 %, respectively. However, the levels of SOD, POD, CAT, and GSH decreased by 43.6 %, 24.1 %, 16.4 %, and 43.1 %, respectively. Applying CaO-NPs elevated Cd stress-induced activities of antioxidant enzymes, thereby diminishing ROS production. Scanning electron microscopy revealed that cadmium stress impedes root hair formation, and the epidermis exhibits damage resembling tugging, which was more pronounced in the mutant. Moreover, RNA-seq analysis revealed discrepancies in the genes of metal transport protein genes, ROS genes, and carbohydrate metabolism pathways between wild-type and mutant rice. GO and KEGG analyses revealed specific pathways related to plant sucrose metabolism and Cd tolerance. We conclude that mutations in the OsSUT2 and OsSUT4 genes reduce Cd tolerance in rice. • Knockout of OsSUT2 and OsSUT4 reduces rice tolerance to cadmium. • Mutant line exhibited differences in metal transporters and carbohydrate metabolism pathways. • Cadmium inhibits root growth in rice. • CaO-NPs enhanced Cd tolerance by reshaping calcium signaling and glucose metabolism. • CaO-NPs can alleviate the toxicity of cadmium in rice.