Effects of Shading on Photosynthetic Characteristics and Metabolism of Cigar Tobacco Leaves

Abstract

Shading is a conventional cultivation method in crop production. However, the effects of shading on photosynthesis and metabolism of cigar leaves remain unclear. Here, the effects of shading on tobacco photosynthesis characteristics and metabolome were studied by setting light transmittance of 100%, 90%, 80%, 70% and 60%. The soluble sugar concentration and soluble protein concentration of cigar leaves at 70% and 60% shading treatments increased by 149.18% and 117.98%, and 174.48% and 195.91%, respectively, compared with that at 100% light transmittance at mature stage. A total of 702 differential metabolites were detected in cigar leaves among the different shading treatments. The metabolites mainly contain flavonoids, such as lignin, sesquiterpenoids, Metabolic pathways are enriched in amino acid metabolism, secondary metabolites biosynthesis and lipid metabolism. Six key metabolites are detected: Chlorogenic Acid, D-Glucosaminide, D-Urobilin, Farnesylcysteine, Hydroxyatrazine and Sucrose. Token together, our study showed that shading could significantly affect the photosynthesis and metabolism of cigar leaves, resulting in the accumulation of primary metabolites, soluble sugar and soluble protein in leaves, which was beneficial to cigar plant growth and quality formation.