Optimizing tobacco (Nicotiana tabacum L.) carbon metabolism regulation via topping: A study based on multi-omics

Topping eliminates the apical dominance of tobacco, alters the structure of tobacco leaves, and regulates the chemical composition of tobacco leaves. This study investigated how different topping periods affect photosynthetic carbon metabolism and related regulatory mechanisms in tobacco leaves through integrated physiological, proteomic, and metabolomic analyses. The results indicated that topping could effectively promote the broadening of leaves and the increase of leaf area, and significantly enhance the photosynthetic rate of leaves. Furthermore, topping promotes the Calvin cycle and sucrose metabolism in photosynthetic organisms, increasing starch content and reducing sucrose content. Overall, topping promotes photosynthetic carbon metabolism. These results not only contribute a theoretical basis for the response mechanism and physiological changes in tobacco as the target products under different topping periods but also providing theoretical support for optimizing tobacco planting practices. • In the topping treatments, the densification of the chloroplast basal lamella gradually intensified. • Topping promotes the expression of TPI, FBP, SBPase, rbcL, and prk. • The reduction of TPI activity leads to the poor development of chloroplasts in leaves. • WAXY and SUS regulate the distribution of carbon sources between starch and sucrose synthesis.