Knockout of Suppresses Carbon Assimilation and Alters Nitrogen Metabolism in Tomato Plants.

Sedoheptulose-1,7-bisphosphatase (SBPase) is an enzyme in the Calvin⁻Benson cycle and has been documented to be important in carbon assimilation, growth and stress tolerance in plants. However, information on the impact of SBPase on carbon assimilation and nitrogen metabolism in tomato plants () is rather limited. In the present study, we investigated the role of SBPase in carbon assimilation and nitrogen metabolism in tomato plants by knocking out SBPase gene using clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) gene editing technology. Compared with wild-type plants, mutant plants displayed severe growth retardation. Further analyses showed that knockout of led to a substantial reduction in SBPase activity and as a consequence, ribulose-1,5-bisphosphate (RuBP) regeneration and carbon assimilation rate were dramatically inhibited in mutant plants. It was further observed that much lower levels of sucrose and starch were accumulated in mutant plants than their wild-type counterparts during the photoperiod. Intriguingly, mutation in altered nitrogen metabolism as demonstrated by changes in levels of protein and amino acids and activities of nitrogen metabolic enzymes. Collectively, our data suggest that is required for optimal growth, carbon assimilation and nitrogen metabolism in tomato plants.